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Transcript 
Nottingham University Academy of Science and Technology
Q1.
A burglar alarm system is to be implemented that has the following sensors:
•
•
a door sensor D that outputs TRUE when the door is open and FALSE when the
door is shut
a pressure mat sensor M that outputs TRUE while a weight is detected on it and
FALSE when no weight is detected on it.
The alarm also has a key K that turns the alarm on and off. K outputs a TRUE signal
when the alarm is switched on and FALSE when the alarm is off.
The alarm output A sounds a bell. It should be TRUE if:
•
•
the alarm is on AND
either of the sensors D or M are set to the value TRUE.
(a)
In the space below, draw a logic circuit that will behave as described above for the
inputs D, M and K and the output A.
(2)
(b)
Write a Boolean expression to represent the logic of this alarm system.
A=...................................................................................................................
(2)
(c)
In this alarm system, the alarm bell will sound only while the door is open or a
weight is placed on the pressure mat. If someone who has stepped on to the mat
moves off it, or an open door is closed, the alarm bell will stop ringing.
A D-type flip-flop could be incorporated into the logic circuit so that the alarm bell
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Nottingham University Academy of Science and Technology
would continue to sound after a person closed the door or moved off the pressure
mat.
Explain how this could be achieved. In your answer refer to:
•
•
•
why a D-type flip-flop would be suitable for this task
where the D-type flip-flop would need to be inserted into the circuit
what additional input the D-type flip-flop would need.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 7 marks)
Q2.
Figure 1 shows the structure of an example machine code instruction, taken from the
instruction set of a particular processor.
Figure 1
(a)
How many different basic machine operations could be supported by the instruction
set of the processor used in the example in Figure 1?
(1)
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Nottingham University Academy of Science and Technology
Figure 2 shows an assembly language program together with the contents of a
section of the main memory of the computer that the program will be executed on.
The assembly language instruction set that has been used to write the program is
listed in Table 1.The lines of the assembly language program have been numbered
to help you answer question parts (b) to (d)
Figure 2
Line
(b)
Command
1
LDR
R2,
#100
2
LDR
R3,
101
3
ADD
R2,
R2,
4
LSL
R3,
R2,
5
HALT
Memory
Address
(in decimal)
Main Memory
Contents
(in decimal)
R3
100
23
#1
101
10
102
62
103
18
What value will be stored in register R2 immediately after the command in line 1 has
been executed?
........................................................................................................................
(1)
(c)
What value will be stored in register R2 immediately after the program has executed
the commands from line 1 through to line 3?
........................................................................................................................
(1)
(d)
What value will be stored in register R3 after the complete program has finished
executing?
........................................................................................................................
Table 1
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Nottingham University Academy of Science and Technology
LDR Rd, <memory ref>
Load the value stored in the memory location specified by
<memory ref> into register d.
STR Rd, <memory ref>
Store the value that is in register d into the memory location
specified by <memory ref>.
ADD Rd, Rn, <operand2>
Add the value specified in <operand2> to the value in register
n and store the result in register d.
SUB Rd, Rn, <operand2>
Subtract the value specified by <operand2> from the value in
register n and store the result in register d.
MOV Rd, <operand2>
Copy the value specified by <operand2> into register d.
CMP Rn, <operand2>
Compare the value stored in register n with the value specified
by <operand2>.
B <label>
Always branch to the instruction at position <label> in the
program.
B<condition> <label>
Conditionally branch to the instruction at position <label> in
the program if the last comparison met the criteria specified by
the <condition>. Possible values for <condition> and their
meaning are:
•
•
•
•
EQ: Equal to.
NE: Not equal to.
GT: Greater than.
LT: Less than.
AND Rd, Rn, <operand2>
Perform a bitwise logical AND operation between the value in
register n and the value specified by <operand2> and store the
result in register d.
ORR Rd, Rn, <operand2>
Perform a bitwise logical OR operation between the value in
register n and the value specified by <operand2> and store the
result in register d.
EOR Rd, Rn, <operand2>
Perform a bitwise logical exclusive or (XOR) operation between
the value in register n and the value specified by <operand2>
and store the result in register d.
MVN Rd, <operand2>
Perform a bitwise logical NOT operation on the value specified
by <operand2> and store the result in register d.
LSL Rd, Rn, <operand2>
Logically shift left the value stored in register n by the number
of bits specified by <operand2> and store the result in register
d.
LSR Rd, Rn, <operand2>
Logically shift right the value stored in register n by the number
of bits specified by <operand2> and store the result in register
d.
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Nottingham University Academy of Science and Technology
HALT
Stops the execution of the program.
Interpretation of <operand2>
<operand2> can be interpreted in two different ways, depending upon whether the first
symbol is a # or an R:
•
•
# - use the decimal value specified after the #, eg #25 means use the decimal value
25.
Rm - use the value stored in register m, eg R6 means use the value stored in register
6.
The available general purpose registers that the programmer can use are numbered 0 to
12.
Programs written in a high-level language can be compiled or interpreted.
Companies that develop computer programs to sell usually compile the final version of a
program before distributing it to customers.
(e)
Explain why the final version of a computer program is usually translated using a
compiler.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(f)
The JavaScript programming language can be used to write programs that are
executed in a web browser on any Internet user’s computer.
Explain why programs written in the JavaScript language, to be executed in a web
browser, are interpreted rather than compiled.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 8 marks)
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Nottingham University Academy of Science and Technology
Q3.
(a)
Complete the table below and draw the symbol for an AND gate in the box.
Truth table for an AND gate
Input A
Input B
AND gate symbol
Output
(2)
(b)
Using the laws of Boolean algebra, simplify the following Boolean expression.
A.B. (A + B)
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Answer ............................................
(3)
(c)
Using the laws of Boolean algebra, simplify the following Boolean expression.
(X + Y).(X +
)
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
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Nottingham University Academy of Science and Technology
Answer ............................................
(3)
(Total 8 marks)
Q4.
The tables below show two versions of the same segment of a program.
Version A
Version B
if x > 0:
y = y + 2
else:
y = y - 1
(a)
00011100
00101010
11101010
00101100
00110000
10010010
00000010
10010001
Shade in one lozenge to indicate which version, A or B, in the tables above
represents object code.
Version A
Version B
(1)
(b)
Describe two differences between a compiler and an interpreter.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
Explain what intermediate code is and why some compilers will produce
intermediate code as the final output.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 5 marks)
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Nottingham University Academy of Science and Technology
Q5.
(a)
First and second generation languages are known as low-level languages.
What is meant by the term low-level language?
........................................................................................................................
........................................................................................................................
(1)
(b)
Programs written using a high-level language are easier to maintain and understand
than programs written in a low-level language.
Describe two ways in which high-level languages can make this possible.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
A student new to programming has heard that some languages are compiled and
others are interpreted, and that compilers and interpreters are both known as types
of translator.
Describe to this student:
•
•
•
•
the role of a translator
the differences between a compiler and an interpreter
a situation where you would use a compiler
a situation where you would use an interpreter.
In your answer, you will be assessed on your ability to use good English and to
organise your answer clearly in complete sentences, using specialist vocabulary
where appropriate.
Use the space provided to write your answer to this question
........................................................................................................................
........................................................................................................................
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Nottingham University Academy of Science and Technology
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(6)
(Total 9 marks)
Q6.
(a)
Complete the truth table below for a NAND gate.
NAND gate
Input A
Input B
0
0
0
1
1
0
1
1
Output
(1)
(b)
Multiplexors are used in electronic switching.
A 2-to-1 multiplexor has a Boolean equation where A and B are two inputs, S is the
selector input, and Q is the output.
(i)
Complete the truth table for the above Boolean equation.
S
A
B
0
0
0
B.S
Page 9
Q
Nottingham University Academy of Science and Technology
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
(3)
(ii)
Draw a circuit for the Boolean equation in the rectangle below.
(4)
(iii)
By considering its inputs and outputs, describe what the 2-to-1 multiplexor
circuit does.
...............................................................................................................
...............................................................................................................
...............................................................................................................
(1)
(Total 9 marks)
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Nottingham University Academy of Science and Technology
Q7.
Explain the role of the operating system and state the important tasks which are carried
out by most operating systems.
Beyond those of a standard operating system, describe the additional operational
characteristics that you would expect a real time operating system to have.
In your answer you will be assessed on your ability to use good English, and to organise
your answer clearly in complete sentences, using specialist vocabulary where appropriate.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
(Total 7 marks)
Q8.
The diagram below shows the classifications of various types of software used on a
computer system and some examples of these types.
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Nottingham University Academy of Science and Technology
(a)
Complete the diagram by suggesting labels for the boxes numbered 1 to 4 in the
diagram.
1 .....................................................................................................................
2 .....................................................................................................................
3 .....................................................................................................................
4 .....................................................................................................................
(4)
(b)
(i)
Machine code is the first generation of programming language.
What is the second generation of programming language?
...............................................................................................................
(1)
(ii)
A program written in a second generation programming language has been
loaded into a computer. In this form it cannot be directly executed on this
computer.
What has to be done to make an executable form of the program, which can
be directly executed by this computer, and what would be used, typically, to do
this?
...............................................................................................................
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Nottingham University Academy of Science and Technology
...............................................................................................................
...............................................................................................................
(2)
(iii)
A programmer then finds that when the executable form of the program is
transferred unaltered to another computer, the program does not run and an
error message is displayed.
Why might the executable form of the program not be able to run on this
computer?
...............................................................................................................
...............................................................................................................
(1)
(Total 8 marks)
Q9.
(a)
Complete the truth tables for the following logic gates.
OR gate
Input A
Input B
0
0
0
1
1
0
1
1
Output
NAND gate
Input A
Input B
0
0
0
1
1
0
1
1
Output
(2)
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Nottingham University Academy of Science and Technology
(b)
Represent the following Boolean equation as a logic circuit by completing the
diagram below.
(5)
(c)
Simplify the following expression.
Show each stage of your working in the space below.
(2)
Final answer .......................................................................................................
(1)
(Total 10 marks)
Q10.
A company operates a Local Area Network (LAN) which is used by its employees.
The diagram below shows the topology of the LAN.
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Nottingham University Academy of Science and Technology
(a)
Suggest suitable IP addresses for:
(i)
the ‘Router 2’ port labelled A ................................................................
(1)
(ii)
the ‘Router 2’ port labelled B ................................................................
(1)
(iii)
the network adapter card in the computer labelled C ...........................
(1)
(b)
The network has been divided into segments.
Explain why networks that use a bus topology are often segmented.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
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Nottingham University Academy of Science and Technology
(2)
(c)
Previously, employees of the company used word processing and spreadsheet
software that was installed locally on each of the individual computers on the
network. Now, employees use software with similar features as a service (SaaS).
The software runs on a web server and is accessed through the Internet.
(i)
Explain two advantages of using software as a service instead of using
software installed locally on individual computers.
Advantage 1 .........................................................................................
...............................................................................................................
...............................................................................................................
Advantage 2 ..........................................................................................
...............................................................................................................
...............................................................................................................
(2)
(ii)
Explain one disadvantage of using software as a service instead of using
software installed locally on individual computers.
...............................................................................................................
...............................................................................................................
...............................................................................................................
(1)
(d)
One difference between a Local Area Network (LAN) and a Wide Area Network
(WAN)is the area that they cover. Describe two other differences between a LAN
and a WAN.
Difference 1 ...................................................................................................
........................................................................................................................
Difference 2 ....................................................................................................
........................................................................................................................
(2)
(Total 10 marks)
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Nottingham University Academy of Science and Technology
Q11.
For each problem in the table below, place a tick in the appropriate box to indicate the
generation of programming language best suited to developing a solution to the problem.
Do not tick more than one box in each row.
Generation
Problem
1st
2nd
4th
Developing a diagnosis program for medical symptoms
Developing a program for an embedded microprocessor for
a washing machine
(Total 2 marks)
Q12.
A school robotics club has recently purchased a robotics kit after the teacher in charge
saw an advert in a magazine. The advert is reproduced below.
RoboEddy - a new educational robot
Specification
Hardware
500 Mhz processor
32 MB RAM
4 timers
Wi-Fi communications via WLAN 802.11g radio
Dual H-bridge motor driver
Software
Built in interpreter for the high level language RobotC
Directly run assembly code
XMODEM protocol for reliable file transfer
Support for various analogue and digital sensors
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Nottingham University Academy of Science and Technology
(a)
Using the XMODEM protocol, students at the robotics club can copy a RobotC
program prepared on a desktop computer to the robot.
What is meant by the term protocol?
........................................................................................................................
........................................................................................................................
(1)
(b)
The RobotC program that has been copied to the robot can be executed by the
built-in interpreter.
How does a high level language interpreter work?
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
The robot processor is different in some ways from a processor in a desktop
computer, but it still follows the stored program concept.
What is meant by the term stored program concept?
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(d)
As well as using RobotC, it is also possible to program the robot using assembly
language.
The motor driver uses memory locations to store the current speed of each motor.
The left motor speed is stored in memory location 21 and the right motor speed is
stored in memory location 22.
The following set of three assembly language instructions can be used to take basic
control of the motors:
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Nottingham University Academy of Science and Technology
LOAD XX
- load a value from memory location XX into the accumulator
ADD XX
- add the value stored in memory location XX to the accumulator
STORE XX
- store the value in the accumulator in memory location XX
Selecting from the set of three instructions above, write a sequence of instructions
that will swap the current left motor speed with the current right motor speed. Your
program may use memory location 23 for temporary storage.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(e)
The students develop a program that can sort coloured balls into piles but it is found
that the program is not very effective.
With regards to touch and vision, state three factors why a robot may find a task,
such as sorting coloured balls, a hard task whereas for a 4-year-old child it is a
relatively easy one.
Factor 1 ..........................................................................................................
........................................................................................................................
Factor 2 ..........................................................................................................
........................................................................................................................
Factor 3 ..........................................................................................................
........................................................................................................................
(3)
(f)
The robot identifies the colour of the balls using a digital still camera component.
(i)
Describe the principles of operation of a digital still camera.
...............................................................................................................
...............................................................................................................
...............................................................................................................
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Nottingham University Academy of Science and Technology
...............................................................................................................
...............................................................................................................
...............................................................................................................
(3)
(ii)
The digital still camera component can take high resolution images but the
students have chosen to program it to take low resolution images instead.
Give a reason why the students might have only used a low resolution.
...............................................................................................................
...............................................................................................................
...............................................................................................................
(1)
(Total 16 marks)
Q13.
(a)
State the names of the logic gates represented by each of the three truth tables
below.
Input A
Input B
Output
0
0
0
0
1
0
1
0
0
1
1
1
Input A
Input B
Output
0
0
1
0
1
0
1
0
0
1
1
0
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Logic gate name ....................................
Logic gate name ....................................
Nottingham University Academy of Science and Technology
Input A
Input B
Output
0
0
0
0
1
1
1
0
1
1
1
0
Logic gate name ....................................
(3)
(b)
Simplify the following Boolean expressions.
(i)
B . (A+ )
...............................................................................................................
...............................................................................................................
(1)
(ii)
A.B+B
...............................................................................................................
...............................................................................................................
(1)
(iii)
...............................................................................................................
...............................................................................................................
(2)
(c)
Draw a logic circuit for the following Boolean expression:
Q = (A ⊕ B) . B
You will need to make use of the symbols below when drawing your logic circuit.
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Nottingham University Academy of Science and Technology
(2)
(Total 9 marks)
Q14.
A school has recently launched a ‘Parent Portal’ which is a website that provides
information from the school. By logging on to the portal a parent can access the
information that is stored about their son or daughter. This information includes academic
reports, discipline records and other personal data.
(a)
A parent recently contacted the school because he was concerned that when he
logged on to read his daughter’s report he could access the reports of all the other
students.
The school should immediately look into this concern as a law has been broken.
State the full name of the law that has been broken.
........................................................................................................................
(1)
(b)
Which principle of the law identified in your answer to part (a) has been broken?
........................................................................................................................
........................................................................................................................
(1)
(c)
State another principle of the law identified in your answer to part (a).
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Nottingham University Academy of Science and Technology
........................................................................................................................
........................................................................................................................
(1)
(d)
A parent also noted that the website was using HTTP (HyperText Transfer
Protocol).
Why should the school be concerned about the use of this protocol and which
protocol would you recommend that the school should use instead?
Why concerned ..............................................................................................
.........................................................................................................................
Suggested protocol .........................................................................................
(2)
(e)
The process of writing reports and then allowing access to these reports via the
parent portal involves the use of many different categories of software.
Below is a list of different categories of software:
Operating system, Utility program, Special purpose application software, Bespoke
application software, General purpose application software
Complete Table 1 by writing the correct category from the list above in the
Category column next to the appropriate Software.
You should not use a category more than once.
Table 1
Software
Category
Word processor used to write the pupil
reports
The parent portal web application
which was programmed for this school
The web server software run by the
school
(3)
(Total 8 marks)
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Nottingham University Academy of Science and Technology
Q15.
A computer system is made up of software and hardware.
Explain what is meant by these two terms.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
(Total 2 marks)
Q16.
When writing a program, a programmer could use an assembly language, a high level
imperative language or a high level declarative language.
Outline the major differences in each of these three approaches. For each language type,
your answer could include:
•
advantages and disadvantages compared to other language types
•
how the programmer would express their programs
•
what translation software could be used, if applicable
•
a situation where it might be the most appropriate choice.
In your answer you will be assessed on your ability to use good English and to organise
your answer clearly in complete sentences, using specialist vocabulary where appropriate.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
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Nottingham University Academy of Science and Technology
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
(Total 8 marks)
Q17.
(a)
Represent the Boolean equation Q =
as a logic circuit by drawing a diagram
in the space below using only the following symbols:
AND
NOT
(3)
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Nottingham University Academy of Science and Technology
(b)
Use the following truth tables to demonstrate that A + B =
A
B
0
A+B
A
B
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
(4)
(c)
What is the name commonly associated with the statement A + B =
?
........................................................................................................................
(1)
(d)
Simplify the Boolean expression below.
A.B.
+ A.
Show each stage of your working in the space below.
(2)
Final answer ..................................................................................................
(1)
(Total 11 marks)
Q18.
(a)
The table below lists some components of a computer system.
Put one tick on each row to identify each component as either:
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Nottingham University Academy of Science and Technology
•
software
•
hardware
•
hardware and software.
Component
Software
Hardware
Hardware and
software
Wireless router
Compiler
Keyboard
(3)
(b)
System software performs the tasks needed to operate the hardware. The operating
system and library programs are system software.
(i)
State one role of the operating system.
...............................................................................................................
(1)
(ii)
State one purpose of library programs.
...............................................................................................................
(1)
(c)
A company is looking at purchasing some bespoke software to help them run their
ordering and purchasing activities.
(i)
State one advantage of purchasing bespoke software.
...............................................................................................................
...............................................................................................................
(1)
(ii)
State one disadvantage of purchasing bespoke software.
...............................................................................................................
...............................................................................................................
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Nottingham University Academy of Science and Technology
(1)
(Total 7 marks)
Q19.
There are many third generation programming languages available. Some of these can be
classified as imperative high level languages.
(a)
Explain what is meant by the term imperative high level language?
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Give one reason for there being so many third generation programming languages.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(1)
(Total 3 marks)
Q20.
(a)
Complete the truth tables for the following logic gates.
AND Gate
Input X
Input Y
0
XOR Gate
Input Q
Output
X
Input Y
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
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Output Q
Nottingham University Academy of Science and Technology
(2)
(b)
A line-following robot has three sensors. It moves along a black line on a white
background whilst the following conditions are met:
•
the ultrasonic sensor U does not detect any obstacle
•
either, but not both, of the infrared sensors L and R are on the black line.
Sensor U returns 1 if it detects an obstacle and 0 if the path is clear.
Sensors L and R each return 1 if they detect black and 0 if they detect white.
A logic circuit will process the input from the sensors and produce an output M.
M should be 1 if the robot is to move and 0 if the robot should stop.
(i)
Represent the output M as a Boolean expression.
M = ........................................................................................................
(3)
(ii)
The following symbols are used to represent logic gates:
NOT
OR
AND
XOR
NOR
NAND
Using a combination of any of the above logic gates draw a logic circuit for this
system in the box below. You will not need to use all of the different types of
logic gates.
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Nottingham University Academy of Science and Technology
(3)
(c)
Apply De Morgan’s Law(s) to the following expression and simplify the result.
Show the stages of your working.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
Final answer ..................................................................................................
(1)
(Total 11 marks)
Q21.
An operating system is designed to hide the complexities of the hardware from the user
and to manage the hardware and other resources.
Give three different types of management of either hardware or other resources that are
performed by an operating system.
1 ..............................................................................................................................
.................................................................................................................................
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Nottingham University Academy of Science and Technology
2 ..............................................................................................................................
.................................................................................................................................
3 ..............................................................................................................................
.................................................................................................................................
(Total 3 marks)
Q22.
The diagram below shows program code developed using different generations of
programming languages.
Program 1 (with comments)
//Calculate
FirstVar := 47;
SecondVar := FirstVar + 2;
FourthVar := ThirdVar;
Program 2 (with comments)
AB2F
BC5D
E402
BCFF
AC61
BC4A
(a)
;
;
;
;
;
;
Load value 2F into accumulator
Store contents of accumulator at address 5D
Add value 2 to accumulator
Store contents of accumulator at address FF
Load accumulator with contents of address 61
Store contents of accumulator at address 4A
What generation of programming language was used to write Program 1?
........................................................................................................................
(1)
(b)
Machine code can be represented in different numeric formats.
(i)
Which numeric format is used by the machine code program in Program 2?
...............................................................................................................
(1)
(ii)
State one reason for using this format.
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Nottingham University Academy of Science and Technology
...............................................................................................................
(1)
(iii)
The machine for which Program 2 has been written has limited addressing
capability.
What are the lowest and highest memory addresses that can be addressed by
this machine?
Lowest address: ...................................................................................
Highest address: ...................................................................................
(1)
(c)
Give an example of a situation for which it would be appropriate to write a program
in a low level language (ie machine code or assembly language).
........................................................................................................................
........................................................................................................................
(1)
(d)
Explain the differences between a compiler and an interpreter
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
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Nottingham University Academy of Science and Technology
........................................................................................................................
(4)
(Total 9 marks)
Q23.
The diagram below shows a logic circuit.
(a)
Write a Boolean expression for D.
........................................................................................................................
(1)
(b)
Write a Boolean expression for B.
........................................................................................................................
(1)
(c)
The diagram below shows a different logic circuit.
(i)
Complete the truth table below for the logic circuit in the diagram above.
Inputs
X
Outputs
Y
C
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S
Nottingham University Academy of Science and Technology
0
0
0
1
1
0
1
1
(2)
(ii)
What arithmetic function does the logic circuit in the diagram above perform?
...............................................................................................................
(1)
(d)
Without using a truth table, simplify the Boolean expression below.
(X+Y).(X+
)
Show the stages of your working.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
Final answer ..................................................................................................
(1)
(Total 9 marks)
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Nottingham University Academy of Science and Technology
Q24.
Software can be categorised as either system software or application software.
(a)
The table shown below lists three different examples of application software.
Put one tick in each row of the table to show which category each software program
belongs to.
General Purpose
Software
Special
Purpose
Software
Bespoke
Software
Word Processor
Payroll Software
Flight Control
Software
(3)
(b)
The diagram below shows an incomplete classification of system software.
Suggest suitable labels for boxes 1 to 3 in the diagram above.
1 .....................................................................................................................
2 .....................................................................................................................
3 .....................................................................................................................
(3)
(Total 6 marks)
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Nottingham University Academy of Science and Technology
Q25.
(a)
Complete the truth tables for the following logic gates.
NAND Gate
Input
X
Input
Y
0
0
0
1
1
0
1
1
Output
Q
NOR Gate
Input
X
Input
Y
0
0
0
1
1
0
1
1
Output
Q
(2)
(b)
Represent the Boolean equation Z =
.
+ C in the form of a logic circuit by
drawing a diagram in the space below using the following symbols.
OR
AND
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NOT
Nottingham University Academy of Science and Technology
(3)
(c)
Simplify the Boolean expression below.
Show each stage of your working.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
Final answer ..................................................................................................
(1)
(Total 9 marks)
Q26.
Figure 1 and Figure 2 show different versions of the same program.
Figure 1
(x)
200
201
202
(y)
LOAD
ADD
ADD
Figure 2
(z)
7
3
6
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(x)
(y)
200
201
202
01010110
11010000
11010000
(z)
00000111
00000011
00000110
Nottingham University Academy of Science and Technology
203
(a)
STORE
255
203
11110000
11111111
What generation of programming language is shown in Figure 2?
........................................................................................................................
(1)
(b)
In both figures above there is a column labelled (x).
What would be a suitable heading for this column?
........................................................................................................................
(1)
(c)
In both tables the instruction is split into two parts.
What are the names of the instruction parts in columns (y) and (z)?
(y) ...................................................................................................................
(z) ...................................................................................................................
(2)
(d)
What is the relationship between the instructions in Figure 1 and Figure 2?
........................................................................................................................
........................................................................................................................
(1)
(Total 5 marks)
Q27.
A computer programmer, developing a theatre seat booking system, has decided to use
an event-driven object-oriented programming language.
(a)
The operating system that is installed on the computer that the new booking system
will be used on is an interactive network operating system. This has the
characteristics of both an interactive operating system and a network operating
system.
Explain what is meant by the terms interactive operating system and network
operating system.
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Nottingham University Academy of Science and Technology
Interactive operating system: ........................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Network operating system: ............................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
To allow it to work with the computer’s operating system, the programs developed
by the programmer should be event-driven.
Explain how an event–driven program works.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 4 marks)
Q28.
The diagram below shows a logic circuit.
Complete the truth table for the inputs that have been given.
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Nottingham University Academy of Science and Technology
Inputs
A
B
C
D
E
F
0
0
1
1
0
0
0
1
1
1
0
1
1
0
1
1
1
0
1
1
1
1
1
1
G
H
K
(Total 3 marks)
Q29.
Write the following Boolean expressions in their simplest forms.
(a)
........................................................................................................................
(1)
(b)
........................................................................................................................
(1)
(c)
........................................................................................................................
(1)
(d)
A . (B+1)
........................................................................................................................
(1)
(Total 4 marks)
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Nottingham University Academy of Science and Technology
Q30.
(a)
One type of software can be described by the phrase "performs tasks needed to
operate the hardware".
What type of software is being described?
........................................................................................................................
(1)
(b)
(i)
Explain what is meant by general purpose application software.
...............................................................................................................
...............................................................................................................
(1)
(ii)
Give one example of general purpose application software.
...............................................................................................................
(1)
(c)
An IT manager needs to buy software to manage stock control.
(i)
Why might the manager choose a special purpose application package rather
than a bespoke solution? Give two reasons.
1.............................................................................................................
...............................................................................................................
2.............................................................................................................
...............................................................................................................
(2)
(ii)
Although special purpose application packages for stock control are available,
explain why the IT manager might choose to order a bespoke piece of
software.
...............................................................................................................
...............................................................................................................
(1)
(Total 6 marks)
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Nottingham University Academy of Science and Technology
Q31.
A programmer could use either an assembly language or a high level language to code
programs for sale.
(a)
Give two limitations of using assembly language to code a program.
1 .....................................................................................................................
........................................................................................................................
2 .....................................................................................................................
........................................................................................................................
(2)
(b)
If a program is coded using a high level language, then either a compiler or an
interpreter will need to be used.
Give two advantages of using a compiler, rather than an interpreter, to prepare a
runnable program ready for sale.
1 .....................................................................................................................
........................................................................................................................
........................................................................................................................
2 .....................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 4 marks)
Q32.
What are machines good and bad at, in comparison to humans?
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
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Nottingham University Academy of Science and Technology
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
(Total 4 marks)
Q33.
(a)
Define the following terms.
(i)
Hardware: ..............................................................................................
...............................................................................................................
(1)
(ii)
Software: ...............................................................................................
...............................................................................................................
(1)
(b)
The diagram below shows the classification of various types of software used on a
computer system and some examples of these types.
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Nottingham University Academy of Science and Technology
Complete the labelling of the diagram above by suggesting labels for 1 to 4 in the
diagram.
1 .......................................................... 2 ....................................................
3 ..........................................................
4 ....................................................
(4)
(Total 6 marks)
Q34.
The diagram below shows the processor registers and busses that are used during the
fetch part of the fetch-execute cycle, together with the main memory. The values stored in
memory locations 0 to 6 in the main memory are machine code instructions.
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Nottingham University Academy of Science and Technology
(a)
Name the components that are labelled with the numbers 1 to 4. In the case of
register names, the full names must be stated.
Number
Component Name
(4)
(b)
Explain what happens during the decode and execute stages of the fetch-execute
cycle.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(c)
The machine code instructions in the main memory in the diagram above are shown
in binary.
When programmers look at machine code instructions they usually prefer to view
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Nottingham University Academy of Science and Technology
them in hexadecimal.
State one reason why this is the case.
........................................................................................................................
........................................................................................................................
(1)
(d)
The machine code instructions in the main memory in the diagram above were
produced when an assembly language program was translated into machine code.
(i)
What type of program translator was used to do this?
...............................................................................................................
(1)
(ii)
Most computer programs are initially written in an imperative high level
language rather than assembly language.
Explain why this is the case.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
(3)
(Total 12 marks)
Q35.
(a)
Complete the truth tables for the following logic gates.
OR Gate
Input A
Input B
0
0
XOR Gate
Output Q
Input A
Input B
0
0
0
1
0
1
Page 46
Output Q
Nottingham University Academy of Science and Technology
1
0
1
0
1
1
1
1
(2)
(b)
Represent the Boolean equation Q = A + B· . as a logic circuit by drawing a
diagram of it in the space below.
(3)
(c)
Simplify the Boolean expression:
B·(A +
)
Show your working.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 8 marks)
Q36.
(a)
Explain the purpose of an operating system.
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Nottingham University Academy of Science and Technology
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Discuss the differences between operating systems designed for desktop
computers and operating systems designed for embedded systems.
In this question you will also be assessed on your ability to use good English and to
organise your answer clearly in complete sentences, using specialist vocabulary
where appropriate.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(4)
(Total 6 marks)
Q37.
Simplify the Boolean expression:
Show your working.
................................................................................................................................
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Nottingham University Academy of Science and Technology
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
(Total 3 marks)
Q38.
Programs written in a high level language can be compiled or interpreted.
(a)
Companies that develop computer programs to sell always compile the final version
of a program before distributing it to customers.
Explain why a compiler is used to produce the final version of a computer program.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Scripting programming languages can be used to write programs which are
interpreted and executed in a web browser on any Internet user’s computer.
Explain why programs written in a scripting language for this purpose are interpreted
rather than compiled.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 4 marks)
Q39.
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Nottingham University Academy of Science and Technology
The role of an operating system is often said to be twofold:
1.
2.
To provide a virtual machine.
To manage the resources of the computer.
(a)
What is meant by “to provide a virtual machine”?
.......................................................................................................................
.......................................................................................................................
(1)
(b)
Name three types of resource managed by the operating system.
1 ....................................................................................................................
2 ....................................................................................................................
3 ....................................................................................................................
(3)
(Total 4 marks)
Q40.
A computer system consists of both hardware and software.
(a)
What is meant by:
(i)
hardware: ............................................................................................
..............................................................................................................
(1)
(ii)
software? .............................................................................................
..............................................................................................................
(1)
(b)
One classification of software is system software.
(i)
What is meant by system software?
..............................................................................................................
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Nottingham University Academy of Science and Technology
..............................................................................................................
(1)
(ii)
Give one example of system software.
..............................................................................................................
(1)
(iii)
Name one other software classification.
..............................................................................................................
(1)
(iv)
Give one example of this type of software. (Not a product name.)
..............................................................................................................
(1)
(Total 6 marks)
Q41.
(a)
Machine code is the first generation of programming languages. All other
generations of programming languages need a program translator before the
program can be executed. Name a type of translator suitable for:
(i)
Second generation language programs:
..............................................................................................................
(1)
(ii)
Third generation language programs:
..............................................................................................................
(1)
(b)
Imperative high level languages are third generation.
Give two characteristics of high level languages that distinguish them from second
generation languages.
1 ...................................................................................................................
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Nottingham University Academy of Science and Technology
2 ...................................................................................................................
(2)
(c)
In one high level language an example of a constant definition would be
CONST
VatRate = 17.5;
State one advantage of using a named constant, like VatRate, rather than the actual
value (17.5) in a high level language program.
.......................................................................................................................
.......................................................................................................................
(1)
(d)
(i)
Name an imperative high level language which you have studied.
..............................................................................................................
(1)
For the language you have named in (d) (i) above, give an example, using the
correct syntax, of:
(ii)
iteration: ...............................................................................................
..............................................................................................................
..............................................................................................................
(2)
(iii)
selection: ..............................................................................................
..............................................................................................................
..............................................................................................................
(2)
(Total 10 marks)
Q42.
(a)
Some of the basic components of a computer system are processor, main memory,
and secondary storage.
(i)
What connects the processor and main memory?
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Nottingham University Academy of Science and Technology
..............................................................................................................
(1)
(ii)
What is the purpose of secondary storage?
..............................................................................................................
..............................................................................................................
(1)
(iii)
Describe what happens during the fetch-execute cycle.
..............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
(2)
(b)
(i)
Machine code is the first generation programming language. What is the
second generation?
..............................................................................................................
(1)
(ii)
A programmer writes a program in a second generation programming
language.
What has to be done to this program before it can be executed?
..............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
(2)
(iii)
Some high level languages are classified as imperative. What is meant by
imperative?
..............................................................................................................
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Nottingham University Academy of Science and Technology
..............................................................................................................
(1)
(iv)
Give an example of an imperative high level language.
..............................................................................................................
(1)
(v)
What is the relationship between an imperative high level language statement
and its machine code equivalent?
..............................................................................................................
..............................................................................................................
(1)
(vi)
Give two disadvantages of programming in first and second generation
programming languages compared with imperative high level languages.
1 ...........................................................................................................
..............................................................................................................
2 ...........................................................................................................
..............................................................................................................
(2)
(Total 12 marks)
Q43.
(a)
Programmers are encouraged to adopt a structured approach to writing programs.
One reason is so that programmers can write code which can be more easily
understood by another programmer.
Explain two other reasons.
1 ....................................................................................................................
.......................................................................................................................
(2)
2 ....................................................................................................................
.......................................................................................................................
(2)
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Nottingham University Academy of Science and Technology
(b)
Give three features of an imperative high level programming language which allow
programmers to write “easy-to-understand” code.
1 ....................................................................................................................
.......................................................................................................................
2 ....................................................................................................................
.......................................................................................................................
3 ....................................................................................................................
.......................................................................................................................
(3)
(c)
Distinguish between a compiler and an interpreter.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(Total 9 marks)
Q44.
Newspapers and magazines are advertising many different specifications of personal
computer systems. Such advertisements feature monitor, disk drives, processor, main
memory and operating system.
(a)
What is the purpose of an operating system?
.......................................................................................................................
.......................................................................................................................
(1)
(b)
What is the function of:
(i)
the processor;
..............................................................................................................
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Nottingham University Academy of Science and Technology
..............................................................................................................
(1)
(ii)
main memory (Immediate Access Store)?
..............................................................................................................
..............................................................................................................
(1)
(c)
The system bus in a computer system is made up of three buses. Name each bus
and give one example of its use.
1 Name...........................................................................................................
(1)
Example..........................................................................................................
........................................................................................................................
(1)
2 Name...........................................................................................................
(1)
Example..........................................................................................................
........................................................................................................................
(1)
3 Name...........................................................................................................
(1)
Example..........................................................................................................
........................................................................................................................
(1)
(Total 9 marks)
Q45.
(a)
Two classifications of software are System Software and Application Software.
What is meant by:
(i)
System Software; ................................................................................
..............................................................................................................
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Nottingham University Academy of Science and Technology
..............................................................................................................
(1)
(ii)
Application Software? ..........................................................................
..............................................................................................................
..............................................................................................................
(1)
(b)
Give an example of:
(i)
System Software; .................................................................................
(1)
(ii)
Application Software. ............................................................................
(1)
(Total 4 marks)
Q46.
Programming languages are subdivided into generations. An imperative high level
language is a third generation language.
(a)
Name the language type for:
(i)
first generation; ....................................................................................
(1)
(ii)
second generation. ...............................................................................
(1)
(b)
Name one specific example of a third generation programming language.
.......................................................................................................................
(1)
(Total 3 marks)
Q47.
(a)
Contrast low-level and high-level programming languages.
.......................................................................................................................
.......................................................................................................................
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Nottingham University Academy of Science and Technology
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(4)
(b)
Describe one situation where a high-level language is inappropriate but a low-level
language could be used.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(Total 6 marks)
Q48.
A particular computer language is supplied with an interpreter and a compiler.
(a)
Give one reason for using the interpreter during development.
.......................................................................................................................
.......................................................................................................................
(1)
(b)
Give two reasons for using the compiler to translate the completed program.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(Total 3 marks)
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Nottingham University Academy of Science and Technology
Q49.
Assemblers and compilers are two kinds of program translators. Write two statements
about each of them to distinguish one from the other.
An assembler
1 ..............................................................................................................................
.................................................................................................................................
2 ..............................................................................................................................
.................................................................................................................................
A compiler
1 ..............................................................................................................................
.................................................................................................................................
2 ..............................................................................................................................
.................................................................................................................................
(Total 4 marks)
Q50.
(a)
What is meant by the phrase client-server operation?
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(b)
Explain the operation of virtual memory.
.......................................................................................................................
.......................................................................................................................
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Nottingham University Academy of Science and Technology
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(4)
(Total 6 marks)
Q51.
(a)
What is meant by system software?
.......................................................................................................................
.......................................................................................................................
(1)
(b)
Give two examples of system software.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(Total 3 marks)
Q52.
(a)
Explain what is meant by a programming language.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(b)
Distinguish between low-level and high-level programming languages.
.......................................................................................................................
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Nottingham University Academy of Science and Technology
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(c)
What must happen to the source code of a program before it can be executed, and
why is this necessary?
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(Total 6 marks)
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Nottingham University Academy of Science and Technology
M1.
(a)
All marks AO2 (apply)
1 mark: inputs D and M connected to an OR gate;
1 mark: inputs K and output of OR gate connected to AND gate plus output
connected to A;
A a logically equivalent circuit
2
(b)
All marks AO2 (apply)
A = (D + M) · K
1 mark: D + M somewhere in expression, even if full expression incorrect
1 mark: fully correct expression
A A logically equivalent expression
2
(c)
1 mark for AO1 (understanding), 1 mark for AO2 (application) and 1 mark
for AO1 (knowledge)
AO1 (understanding):1 mark: Flip-flop will store the state of its input / / Flipflop acts as memory;
AO2 (application):1 mark: Insert into circuit between the output of the OR
gate and the AND gate / / after the AND gate;
AO1 (knowledge):1 mark: Clock signal / / trigger / / signal to indicate when
the value (of the input) should be stored / read;
3
[7]
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Nottingham University Academy of Science and Technology
M2.
(a)
Mark is for AO1 (understanding)
64 / 26;
1
(b)
Mark is for AO2 (apply)
100;
1
(c)
Mark is for AO2 (apply)
110;
A The response given to question part (b) with 10 added on.
1
(d)
Mark is for AO2 (apply)
220;
A The response given to question part (c) multiplied by 2.
1
(e)
All marks AO1 (understanding)
So that source code cannot be accessed by users;
So that it is more convenient for users to run it / / users do not need to have an
interpreter;
So that the program will execute more quickly;
Max 2
2
(f)
All marks AO1 (understanding)
1 mark: Can't know what type of processor will be in user’s computer / /
Internet users have range of computers / devices with different processors; A
References to just different types of computer / device rather than specifically
processors
1 mark: A compiled program will only execute on a processor of specific type /
family / with same instruction set / / A program run using an interpreter can
execute on a computer with any type of processor;
R No compiler exists
2
[8]
M3.
(a)
Marks are for AO1 (knowledge)
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Nottingham University Academy of Science and Technology
A
B
Q
0
0
0
0
1
0
1
0
0
1
1
1
1 mark: Table completed correctly;
1 mark: AND gate symbol drawn;
2
(b)
Marks are for AO2 (apply)
A.B.(A + B)
A.B.A + A.B.B ; [expansion of brackets]
B.A + A.B ;
[use of A.A = A]
A.B ;
[use of A + A = A]
1 mark: Final answer: A.B;
Max 2 for working
3
(c)
(Marks are for AO2 (apply)
X + Y).(X + NOT Y)
XX + X(NOT Y) + XY + Y(NOT Y) ; [expansion of brackets]
X + X(NOT Y) + XY ; [use of X.X = X or use of Y(NOT Y) = 0 ]
X ( 1 + NOT Y + Y ) ; [use of 1 + X = 1]
1 mark: Final answer - X;
Max 2 for working
3
[8]
M4.
(a)
Mark is for AO1 (understanding)
Version: B;
1
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Nottingham University Academy of Science and Technology
(b)
Marks are for AO1 (understanding)
A compiler produces object code whilst an interpreter does not;
A compiler translates the whole of the source code into object code whilst an
interpreter translates line by line;
The object code produced by a compiler will execute faster, (once it is
compiled) than interpreting the source code (every time the program is run)
An interpreter can run (syntactically correct) parts of a program whilst there
are syntax errors in other parts of it, which a compiler cannot;
Max 2
2
(c)
Marks are for AO1 (understanding)
Intermediate code is not (directly) executable / /
Intermediate code will by run / interpreted by a virtual machine / / Compiled
into an executable just before running / just in time;
Intermediate code can be run on different computing platforms / / One solution
can be targeted at multiple platforms;
Max 2
2
[5]
M5.
(a)
A language that is close to the hardware;
Language that interacts with basic hardware / tasks of the computer;
Commands map directly / very closely to processor instruction set;
One instruction maps to one processor instruction;
A processor / architecture dependent language // language that is not
portable;
NE machine code or assembly language
R directly executable by the processor
MAX 1
(b)
HLL allows several machine code statements to be replaced by one high level
statement // HLL program shorter that its low level equivalent;
HLL program expressed in language that is human-oriented / uses English-like
keywords;
A structured English
NE written in English / closer to English
Allow programmers to:
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Nottingham University Academy of Science and Technology
use meaningful identifier names;
use procedures / functions / subroutines / libraries;
use programming structures such as IF THEN ELSE / REPEAT UNTIL;
use data structures such as arrays / lists;
Easier to see logic / structure of program / what is to be executed;
A easier to spot / check errors // easier to debug;
Can maintain one codebase for use across multiple architectures;
MAX 2
(c)
•
•
•
•
•
•
•
•
•
The role of a translator is to take program code / source code and to
translate it into a low-level / machine code
A compiler takes the whole source code and translates it (into machine
code / object code)
Compiled code will execute more quickly
Produces an executable file // no need for compiler to be distributed with
program // no need to distribute source code to execute program
An interpreter works through / translates / recognises program source
code line-by-line
Interpreters call routines built into the interpreter to execute commands
Interpreting code is slower than running compiled code
Can run (parts of) a program using an interpreter even if it contains
syntax errors
Source code is required for the program to be interpreted // when
running interpreted code the interpreter is always required
Situations (MAX 1 each for compiler and interpreter)
Compiler:
•
So that source code cannot be accessed by users
•
When creating an executable file for distribution
•
Where speed of execution is important
•
Where targeting a device with a small amount of memory
Interpreter:
•
To allow execution on a wide range of processors
•
When prototyping and testing / debugging code
•
When no compiler yet exists for the processor
A (example of) building a web-application
How to award marks:
Mark Bands and Description
To achieve a mark in this band, candidates must meet the subject criterion
(SUB) and all 5 of the quality of written communication criteria (QWCx).
SUB
Candidate has made at least five mark-worthy points and covers both
interpreter and compiler with a valid situation for at least one.
QWC1 Text is legible.
QWC2 There are few, if any, errors of spelling, punctuation and grammar.
Meaning is clear.
QWC3 The candidate has selected and used a form and style of writing
appropriate to the purpose and has expressed ideas clearly and
fluently.
QWC4 Sentences (and paragraphs) follow on from one another clearly and
coherently.
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Nottingham University Academy of Science and Technology
QWC5 Appropriate specialist vocabulary has been used.
5-6
To achieve a mark in this band, candidates must meet the subject criterion
(SUB) and 4 of the 5 quality of written communication criteria (QWCx).
SUB
Candidate has made at least three mark-worthy points and covers
both compiler and interpreter.
QWC1 Text is legible.
QWC2 There may be occasional errors of spelling, punctuation and grammar.
Meaning is clear.
QWC3 The candidate has, in the main, used a form and style of writing
appropriate to the purpose, with occasional lapses. The candidate
has expressed ideas clearly and reasonably fluently.
QWC4 The candidate has used well-linked sentences (and paragraphs).
QWC5 Appropriate specialist vocabulary has been used.
3-4
To achieve a mark in this band, candidates must meet the subject criterion
(SUB) and 3 of the 5 quality of written communication criteria (QWCx).
SUB
Candidate has made a small number of relevant points.
QWC1 Most of the text is legible.
QWC2 There may be some errors of spelling, punctuation and grammar but it
should still be possible to understand most of the response.
QWC3 The candidate has used a form and style of writing which has many
deficiencies. Ideas are not always clearly expressed.
QWC4 Sentences (and paragraphs) may not always be well-connected.
QWC5 Specialist vocabulary has been used inappropriately or not at all.
1-2
Candidate has made no relevant points.
0
Note: Even if English is perfect, candidates can only get marks for the points
made at the top of the mark scheme for this question.
If a candidate meets the subject criterion in a band but does not meet the
quality of written communication criteria then drop mark by one band,
providing that at least 4 of the quality of language criteria are met in the lower
band. If 4 criteria are not met then drop by two bands.
MAX 6
[9]
M6.
(a)
Input A
Input B
Output
0
0
1
0
1
1
1
0
1
1
1
0
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Nottingham University Academy of Science and Technology
One mark for having correct values in Output column;
1
(b)
(i)
S
A
B
B.S
Q
0
0
0
1
0
0
0
0
0
1
1
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
0
1
1
0
0
0
0
0
0
1
0
1
0
0
1
1
1
1
0
0
0
0
0
1
1
1
0
0
1
1
A.
Marking:
One mark for the A. column being correct;
One mark for the B.S column being correct;
The final Q column should follow through from the previous two columns
as an OR statement;
3
(ii)
One mark for NOT gate with input from S;
A just a circle on AND gate input from S
One mark for AND gate with input from NOT S and A;
A if no NOT gate from S
One mark for AND gate with input from B and S;
One mark for output from AND gates going into OR gate with output
connect to Q;
4
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Nottingham University Academy of Science and Technology
(iii)
A multiplexor selects one of several input lines / wires and forwards /
duplicates the Boolean value on this one line onto a single line / wire;
If S is 1 then input B is output otherwise input A is output // if S is 0 then
input A is output otherwise input B is output;
Note:
1 can be mapped to on / true / high
0 can be mapped to off / false / low
MAX 1
[9]
M7.
SUBJECT MARKING POINTS:
Role of the operating system (1 point):
To hide the complexities of the hardware from the user // provision of virtual
machine;
Tasks carried out by most operating systems (MAX 3 points):
Processor scheduling // allocation of processors // process scheduling;
A processor management
Thread management;
Context switching;
Inter-process communication;
Memory management // allocation of memory / RAM;
Virtual memory provision // a brief explanation of what virtual memory is;
I / O management // allocation of I / O devices // management of / communication
with (device) driver software ;
A examples of devices
File management // organisation of files on storage devices // loading and saving of
files;
A examples of devices
Interrupt handling;
Power / battery management;
Provision of a user interface // allows user to interact with computer;
Provision of an Application Programming Interface / API (so that application
software can call operating system routines);
A management of system security
A managing communications over a network
A just names of tasks e.g. "memory management"
A “storage management” for one of “memory management” or “file management”
Additional functionality of a real time operating system (MAX 3 points):
Must be able to deal with many events occurring simultaneously;
Must be able to deal with events that occur at unpredictable times;
Must produce output / perform processing within a specified / predictable / known
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Nottingham University Academy of Science and Technology
time interval // Must produce output quickly enough to affect (the source of) the
inputs;
A quickly enough for task, in a timely manner
NE quickly, instantly, in a reasonable time
Must be fail-safe;
Must be able to quickly switch between threads / processes // quickly allocate
memory // quickly handle interrupts;
Must support non-sequential application programs;
HOW TO AWARD MARKS:
Mark Bands and Description
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
and 4 of the 5 quality of written communication criteria (QWCx).
SUB
Candidate has made seven mark-worthy points and successfully covers
all of the three topic areas (role, tasks, real time).
QWC1
Text is legible.
QWC2
There are few, if any, errors of spelling, punctuation and grammar.
Meaning is clear.
QWC3
The candidate has selected and used a form and style of writing
appropriate to the purpose and has expressed ideas clearly and fluently.
QWC4
Sentences (and paragraphs) follow on from one another clearly and
coherently.
QWC5
Appropriate specialist vocabulary has been used.
7
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
and all 5 of the quality of written communication criteria (QWCx).
SUB
Candidate has made at least four mark-worthy points and successfully
covers at least two of the three topic areas (role, tasks, real time).
QWC1
Text is legible.
QWC2
There may be occasional errors of spelling, punctuation and grammar.
Meaning is clear.
QWC3
The candidate has, in the main, used a form and style of writing
appropriate to the purpose, with occasional lapses. The candidate has
expressed ideas clearly and reasonably fluently.
QWC4
The candidate has used well-linked sentences (and paragraphs).
QWC5
Appropriate specialist vocabulary has been used.
4-6
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
and 4 of the 5 quality of written communication criteria (QWCx).
SUB
Candidate has made a small number of relevant points but only
successfully covers one or two of the three topic areas (role, tasks, real
time).
QWC1
Most of the text is legible.
QWC2
There may be some errors of spelling, punctuation and grammar but it
should still be possible to understand most of the response.
QWC3
The candidate has used a form and style of writing which has many
deficiencies. Ideas are not always clearly expressed.
QWC4
Sentences (and paragraphs) may not always be well-connected.
QWC5
Specialist vocabulary has been used inappropriately or not at all.
1-3
Candidate has made no relevant points
0
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Nottingham University Academy of Science and Technology
Note: Even if English is perfect, candidates can only get marks for the points made
at the top of the mark scheme for this question.
If a candidate meets the subject criterion in a band but does not meet the quality of
written communication criteria then drop mark by one band, providing that at least 4
of the quality of language criteria are met in the lower band. If 4 criteria are not met
then drop by two bands.
[7]
M8.
(a)
1
special purpose (application software);
A specific purpose
R special (software) / specialist (software)
2
word processor / / spreadsheet / /
presentation software / program / / database;
A any other sensible answer
R (web) browser
R text editor
3
translator (software / program);
A translating / translation
4
utility (software / program);
R just trade name of a specific piece of software unless used as an example
(ie MS Word)
4
(b)
(i)
assembly (language);
A assembly code
R assembler
1
(ii)
has to be translated into machine code / / each assembly language
instruction will be translated into machine code equivalent;
by an assembler;
A converted for translated
A first generation for machine code
2
(iii)
Because it does not have the same processor (type) / / the instruction set
is different / / different architecture / platform;
(Assembled / linked for a) different operating system;
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Nottingham University Academy of Science and Technology
NE operating software
The program refers to a memory address that does not exist on this
computer / / relocatable code used but addressing system on new
machine different;
not enough memory space;
required peripherals are not available;
required library (code / program) missing;
MAX 1
[8]
M9.
(a)
OR gate
Input A
Input B
Output
0
0
0
0
1
1
1
0
1
1
1
1
Input A
Input B
Output
0
0
1
0
1
1
1
0
1
1
1
0
NAND gate
1 mark for correct output OR gate;
1 mark for correct output NAND gate;
2
(b)
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Nottingham University Academy of Science and Technology
1 mark for inputs A and B connected to AND gate;
1 mark for inputs B and C connected to AND gate;
1 mark for output of AND (A,B input) as only connection going to NOT gate;
1 mark for output of NOT gate plus the AND gate (B,C input) going to OR
gate;
1 mark OR gate as only connection going to NOT gate and output only
connection to Q;
5
(c)
MAX 2 if working out is not logically sound
Example 1:
Having applied De Morgan’s correctly;
Having factorised;
Final answer: B ;
Example 2:
Having applied De Morgan’s correctly;
Expanded bracket;
Simplified elements
Having used C + C.D = C to simplify
Having used C + C.D = C to simplify again
Final answer: B ;
Truth Table Answer
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Nottingham University Academy of Science and Technology
A
B
0
0
0
0
0
0
1
0
1
1
1
0
0
0
0
1
1
1
0
1
X
Y
Z
1 mark for both columns marked X and Y above; (column X could be labelled
A.B )
1 mark for final column Z;
1 mark for final answer: B;
3
[10]
M10.
(a)
(i)
192.168.0.x where x is not 0 or 255;
1
(ii)
192.168.2.x where x is not 0 or 255;
1
(iii)
192.168.2.y where y is not 0 or 255 and is not the same as x in (ii);
1
(b)
Reason: To reduce (network) congestion / / improve throughput / / to cut the
number of collisions*; A faster operation / transmission;
Explanation: by cutting the number of collisions* / / by reducing the number of
stations / computers connected to each section of cabling / / because two
computers in one segment can communicate at the same time as two
computers in another segment;
Note: * = Do not award 2 marks for cutting the number of collisions – only
award one for either reason or explanation.
Reason: To improve security;
Explanation: by localising packet transmission to one segment;
Reason: To improve reliability;
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Nottingham University Academy of Science and Technology
Explanation: By limiting effect of cable failure to one segment;
R answers referencing the computers not working at all
Award marks for either:
•
one reason + explanation
•
two reasons
•
two explanations
2
(c)
(i)
No need for maintenance / / no need to upgrade / / no need to install
patches for software / / could employ fewer technical staff;
Lower hardware requirements for computers (as processing done on
web server); A examples of lower hardware requirements but R just
cheaper hardware
No (high) one-off purchase cost; Platform independence / / can access
the software on many devices; A examples eg PC and tablet.
Software can be used from anywhere that there is an Internet
connection / / from outside of office; Note: To award this point must be
clear that can be accessed from outside of office, just "can be accessed
from any computer" is not enough.
Can still access software and data if a specific computer is not working;
A reduced management cost / effort when a reason is given, such as no
need to install software on each computer, but just "does not need to be
installed on each computer" is not enough on its own.
MAX 2
2
(ii)
Reliance on Internet / / unreliable internet connection may mean
software inaccessible;
Reliance on the company that develops the software to keep providing
the service;
Slow connection speed may make software difficult / annoying to use;
Concern over security of saved documents / / security of transmission;
May be an ongoing cost to pay for using the software;
Lack of control over which version to use / when upgrades happen;
Software may slow when used by many users simultaneously;
Higher cost (to company) of fast internet connection to connect many
computers to SaaS;
MAX 1
1
(d)
LAN usually baseband whilst WAN broadband* / / only one communication
can take place at a time on a LAN whereas multiple communications can take
place simultaneously on a WAN;
LAN communication links have higher speeds than WAN;
LAN has lower latency than WAN;
Lower error rates on LAN than WAN;
Communications medium in LAN likely to be privately owned, whereas likely to
be leased / publicly owned in a WAN;
Use different protocols (at link layer / hardware level);
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Nottingham University Academy of Science and Technology
Different hardware required to connect (A examples);
WAN may have greater security risks (as data transmitted over larger area, on
public system, through more servers or devices);
A WAN may use satellites / microwave whilst LAN may use cables / radio /
WiFi* - this point cannot be awarded for just saying WAN uses cables on LAN
radio or vice-versa as both LAN and WAN can use either of these
MAX 2
Only one side of the difference needs to be provided (as the other is
implicit) except for the points marked with an * for which both sides are
needed.
2
[10]
M11.
First row tick in '4th' column;
Second row tick in '2nd' column;
A Other symbols instead of ticks
R Responses where more than one box is ticked on the same line
[2]
M12.
(a)
A set of rules / regulations (to allow communication between devices) // set of
agreed signals / codes for data exchange;
NE a rule // a regulation // a signal // a code
NE instruction(s)
1
(b)
Analyses statement by statement each line of source code
A runs / translates / executes line by line
R compiles (line by line)
Calls routines to carry out each instruction / statement
Max 2
(c)
Instructions / programs stored (with data) in main memory; A memory // RAM
Program run by fetching, (decoding and executing) instructions
(from main memory)* in sequence;
Program can be replaced by loading another program into (main) memory
Contents of a (main) memory location can be interpreted as either an
instruction or data;
* = This mark can be awarded without the explicit reference to main memory if
main memory has already been mentioned elsewhere in the response.
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Nottingham University Academy of Science and Technology
Otherwise, the answer must make clear that the instructions are coming from
the main memory to get this mark.
3
(d)
LOAD 21
STORE 23
LOAD 22
STORE 21
LOAD 23
STORE 22
1 mark for value from 21 stored into 23;
1 mark for value from 22 being moved to 21;
1 mark for value from 23 being moved to 22;
Alternative :
LOAD 22
STORE 23
LOAD 21
STORE 22
LOAD 23
STORE 21
1 mark for value from 22 stored into 23;
1 mark for value from 21 being moved to 22;
1 mark for value from 23 being moved to 21;
DPT if a different temporary storage area is used
I end of statement separators
Max 2 if the program does not fully work
3
(e)
Robots find it hard to adapt to changes in environment // Robots are unable to
adapt to changes easily;
Robots find it hard to work with 3D vision;
Robots find it hard to detect edges between similar objects // robots find it hard
to perform shape detection;
Robots find it hard to get feedback when gripping items;
Robots find it hard to pick up balls // ball difficult shape to grip // balls can roll
away;
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Nottingham University Academy of Science and Technology
Robots have limited processing power // too many variables to deal with;
Programming for vision/grip is a complex problem;
A child builds up experience of using touch / vision;
A Robot cannot recognise when it makes mistakes;
A Robot can't think for themselves // can’t perform lateral thinking
Max 3
(f)
(i)
(Lens focuses) light / photons onto image sensor;
R if uses ‘reflection’
Image sensor is a CMOS / CCD / photoelectric device;
CCD used ADC to convert measurement of light intensity into binary;
CMOS uses transistors to generate binary value;
Image sensor converts light into discrete / electrical signals / binary;
Image is captured when the shutter is pressed;
Large pixels collect more electrons than small pixels and so produce
better quality images;
Firmware performs data processing to “tidy up” image;
(Colour) filter used to generate data separately for Red, Green, Blue
colour components;
Aperture / shutter speed can be adjusted to cope with varying lighting
conditions;
Image is recorded as group / array of pixels // Image sensor consists of
array of pixel (sensors)//etched into the image sensor’s silicon are pixels;
Image data transferred to robot;
Image data usually stored on solid-state disk;
Max 3
(ii)
Robot has a low powered microprocessor;
Too much image data for the robot to process quickly // smaller
resolution can be processed quicker;
A high resolution image has too much image data for the robot to store //
low resolution uses less storage space;
Do not need high resolution to determine colour of balls;
NE allows more images to be stored
Max 1
[16]
M13.
(a)
AND;
NOR;
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Nottingham University Academy of Science and Technology
XOR; A EXOR // EOR // NEQ // exclusive OR;
3
(b)
(i)
B
1
(ii)
B
1
(iii)
0;;
Award 1 mark if De Morgan's has been applied once correctly but
candidate does not end up simplifying to 0
Example:
Example:
2
(c)
Inputs A and B connected to an XOR gate;
Input from B and output of XOR gate connected to an AND gate with output
going to Q;
2
[9]
M14.
(a)
Data Protection (Act);
1
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Nottingham University Academy of Science and Technology
(b)
Data should be kept securely;
1
(c)
Data should be fairly and lawfully processed;
Data should be obtained for specified and lawful purposes. (A Data should be
processed for limited purposes);
Data should be adequate, relevant and not excessive;
Data should be accurate // kept up to date;
Data should not be kept longer than necessary;
Data should be not transferred to other countries without adequate protection;
Data should be processed in accordance with the rights of the data subjects.
Max 1
(d)
That data is not being encrypted // data is not being sent securely // that
hackers might be able to see personal data;
A the protocol / it is not secure
R website not secure
HTTPS // HyperText Transfer Protocol Secure;
2
(e)
Word processor : General purpose (application software);
Parent portal : Bespoke;
Web server : Special purpose (application software);
3
[8]
M15.
Hardware:
physical components // devices (that make up the computer) //
electrical circuit // electrical components (that make up the computer);
NE components
Software:
programs / instructions that are run/executed (by the computer);
A codes that are run / executed
A programs that enables computer to run
A programs that allow user to perform tasks
Need both parts to gain mark
[2]
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Nottingham University Academy of Science and Technology
M16.
General:
Idea of ‘quicker to write ’ or ‘easier to write ’ [ONE MARK]
EXAMPLES:
Assembly language is quicker to write than machine code //
HLL is quicker to write (compared to assembly code) //
Assembly language is easier to write than machine code // HLL is easier to write
(compared to assembly);
[or opposites – slower to write / harder to write]
Idea of ‘understanding’ [ONE MARK]
EXAMPLES:
Assembly code easier to understand than machine code //
HLL easier to understand than assembly code;
Idea of ‘debugging’ [ONE MARK]
EXAMPLES:
Assembly code easier to debug than machine code // HLL easier to debug (than
assembly code);
Assembly language:
Solution expressed in terms of mnemonics;
A an example of a full instruction (operand and opcode)
Easier to make mistakes in assembly language;
Instruction composed of op-code and operand;
Solution translated by using an assembler;
Code is hard to port to other types of computer // machine-oriented languages;
One assembly language instruction relates to one machine code instruction;
Situation – working on embedded hardware // need for small object code size //
need for fast execution // need to access hardware / registers directly;
Imperative language:
Imperative is where the programmer gives the computer a sequence of instructions
to perform; Selection / Sequence / Iteration constructs available;
A a full example of a selection / iteration construct
Library of pre-written functions available;
Solution translated by using a compiler / interpreter;
A compiler might not be available for a specific processor (disadvantage);
Situation – anything sensible that would need a HLL (for example games
programming)
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Nottingham University Academy of Science and Technology
Declarative language:
(Certain languages) define what is to be computed rather than how the computation
is to be done;
(Certain languages) lack side effects;
(Certain languages) have a clear link to mathematical logic;
(Certain languages) express solutions in terms of facts and rules // rule-based;
(Certain languages) will use an inference engine to work out the answer;
The user asks a question of the system rather than provide an algorithm of the
solution;
Uses back-chaining / backtracking;
(Certain languages) express solutions using markup languages (such as HTML);
(Certain languages) express solutions as CSS / regular expressions / (subset of)
SQL;
A example code from part of a declarative program (ie an SQL statement)
Situation – medical diagnosis // expert systems // database query // creating a web
page / website;
Imperative and Declarative language:
Solution expressed in terms of statements written using English-like keywords;
Code easier than assembly language to port to other types of computer;
One language statement maps to many (more than one) machine code instruction;
Note: accept any sensible situation for each area
Mark Bands and Description
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
and all 5 of the quality of language criteria(QWCx).
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate has covered all three language generations and made at least 7
subject-related points.
Text is legible.
There are few, if any, errors of spelling, punctuation and grammar.
Meaning is clear.
The candidate has selected and used a form and style of writing
appropriate to the purpose and has expressed ideas clearly and
fluently
Sentences (and paragraphs) follow on from one another clearly and
coherently.
Appropriate specialist vocabulary has been used.
7-8
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
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Nottingham University Academy of Science and Technology
and 4 of the 5 quality of language criteria (QWCx).
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate has covered at least 2 of the 3 generations and has made at
least 3 subject-related points.
Text is legible.
There may be occasional errors of spelling, punctuation and grammar.
Meaning is clear.
The candidate has, in the main, used a form and style of writing appropriate
to the purpose, with occasional lapses. The candidate has expressed
ideas clearly and reasonably fluently.
The candidate has used well-linked sentences (and paragraphs).
Appropriate specialist vocabulary has been used.
3-6
To achieve a mark in this band, candidates must meet the subject criterion (SUB)
and 4 of the 5 quality of language criteria (QWCx).
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate may not have covered all generations, but has covered at least
one of them. At least one valid point has been made.
Most of the text is legible.
There may be some errors of spelling, punctuation and grammar but it
should still be possible to understand most of the response.
The candidate has used a form and style of writing which has many
deficiencies. Ideas are not always clearly expressed.
Sentences (and paragraphs) may not always be well-connected.
Specialist vocabulary has been used inappropriately or not at all.
1-2
Candidate has made no relevant points.
0
Note: Even if English is perfect, candidates can only get marks for the points made
at the top of the mark scheme for this question.
If a candidate meets the subject criterion in a band but does not meet the quality of
written communication criteria then drop mark by one band, providing that at least 4
of the quality of language criteria are met in the lower band.
If 4 criteria are not met then drop by two bands.
Max 8
[8]
M17.
(a)
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Nottingham University Academy of Science and Technology
1 mark – logic of first part satisfies NOT A, NOT B;
1 mark – inputs into an AND gate;
1 mark – output from AND gate passes through a NOT gate and connected to
Q;
3
(b)
A
B
A+B
0
0
0
0
1
1
1
0
1
1
1
1
1 mark for correct A + B column;
A
B
0
0
1
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
1
1
0
0
0
1
1 mark for columns
and
column being correct;
1 mark for
column being correct;
1 mark for
column being correct;
Note: Can follow through into
column from previous two
4
(c)
De Morgan's (law);
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Nottingham University Academy of Science and Technology
1
(d)
Mark allocation:
One mark for taking either A, NOT C or A AND NOT C
outside of brackets to produce a correct expression;
One mark for eliminating B in a valid way;
One mark for correct final answer;
Example One:
A.B. + A.
A (B.
+
) - taking A outside of brackets;
A ( (B + 1)) ( B + 1 ) = 1
Simplifying to remove B using B + 1 = 1 ;
B. +
=
Simplifying to remove B using B.
A A(
(B + 1))
→ A.
+
=
;
Final answer A.
Example Two:
A.B.
+ A.
A. (B + 1) – taking outside of brackets;
(B + 1 ) = 1; - simplifying to remove B
A A. (B + 1)
→ A.
Final answer A.
Truth Table Method
A
B
C
A.
A.B. + A.
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
1
1
0
0
1
0
0
1
1
1
0
1
0
0
1
1
0
1
1
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Nottingham University Academy of Science and Technology
1
1
1
0
0
(student answer may have more columns than this)
A mark for having correct column for A.B.
A mark for having correct column for A. ;
Final answer A.
+ A. ;
3
[11]
M18.
(a)
Comp
S/ware
Hardware
Wireless
router
Compiler
Keyboard
Hardware
and
software
TICK;
TICK;
TICK;
A TICK;
A crosses used rather than ticks
R answers where two columns have been ticked in a single row
3
(b)
(i)
Provide an interface between the computer and user;
To manage devices / files / memory;
To provide a virtual machine;
To provide a software platform on which other programs can run // to run
application software;
To hide the complexity of the hardware from the user;
NE to allow user to use hardware
R to execute commands
Max 1
(ii)
To allow sharing of run-time code across programs;
To save memory as routines are only loaded when needed;
To provide access to procedures / functions when writing a program;,
To reduce amount of programming required // time taken to write
program;
Max 1
(c)
(i)
Meets all of the end-user requirements;
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Nottingham University Academy of Science and Technology
Only performs necessary functions;
Can be fitted into existing hardware / software;
Max 1
(ii)
More expensive as have to cover production costs;
Not available immediately // have to wait for software to be written;
Less widely tested so more likely to contain bugs;
Lack of 3rd party support;
NE (more) expensive
R “no testing”
Max 1
[7]
M19.
(a)
Imperative:
Instructions are executed in a programmer defined sequence //
Instructions specify how to solve the problem;
A executed line by line (in sequence)
HLL:
A language that uses English-like/more meaningful keywords // one instruction
maps to several machine code instructions // has structures for
assignment/iteration/selection ;
NE a language that is like English
2
(b)
Languages used for a specific problem type/domain;
A different uses / purposes / tasks
Access to specific data types;
Providing different function libraries;
Languages developed for specific hardware / devices ;
Languages developed for visual applications / GUIs;
Competition between different companies who develop languages;
Max 1
[3]
M20.
(a)
AND Gate
Input X
Input X
Output Q
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Nottingham University Academy of Science and Technology
0
0
0
0
1
0
1
0
0
1
1
1
Input X
Input X
Output Q
0
0
0
0
1
1
1
0
1
1
1
0
XOR Gate
1 mark for each of the output columns
2
(b)
(i)
[Brackets are not necessary]
1 mark for use of correct operands (L,R,U);
1 mark for use of XOR with L,R;
1 mark for NOT U anded with other part;
alternative:
1 mark for use of correct operands (L,R,U);
1 mark for alternative XOR expression;
1 mark for AND NOT U;
alternative:
1 mark for use of correct operands (L,R,U);
1 mark for alternative XOR expression;
1 mark for AND NOT U;
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Nottingham University Academy of Science and Technology
Acceptable notation for symbols
~ for NOT
X.Y allow X AND Y, XэY,X)Y, XY
X+Y allow X OR Y, X(Y, X*Y
3
(ii)
L, R connected to XOR gate;
U connected to NOT gate;
Output of a two input AND gate connected to M;
Max 2 if circuit does not reflect the correct logic
Alternative :
U connected to NOT gate;
Correct gates used for L and R before last AND gate;
Output of a two input AND gate connected to M;
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Nottingham University Academy of Science and Technology
Alternative :
Marked as above alternative.
3
(c)
Solution 1:
[Application of De Morgan’s Law –1 mark]
[allow simplification of double nots at same time]
[Simplification of A.A to A –1 mark]
[Correct solution – 1 mark]
Solution 2:
[Application of De Morgan’s Law –1 mark]
[allow simplification of double nots at same time]
[Simplification of NOT A OR NOT A to NOT A – 1 mark]
[De Morgan’s again to correct solution – 1 mark]
1 mark for De Morgan;
1 mark for simplification;
1 mark for final answer;
Other notations as for section (b)
No working marks for truth table solution (asked to use De Morgan’s in
question)
3
[11]
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Nottingham University Academy of Science and Technology
M21.
Processor management // Allocation of processors // Allocation of
processor time // (process) scheduling // thread management;
A processing management
Allocation/management of RAM / memory // allocation of buffers;
Allocation/management of / control of I/O devices/peripherals // I/O management //
device driver management;
File / backing store / secondary store management / access / organisation;
Power / battery management;
A Interrupt handling;
A Provision of Application Program Interface / API;
A interface between hardware and applications;
A Provision / management of (windows in) user interface;
A Management of system security;
A Answers by example, only one example of each type
A A description of a type of software management but not just “software
management”. e.g. loading of programs, software installation, registering DLLs.
R Software management alone unless role of OS in this is clear e.g. installation of
new software, updating registry
Max 3
[3]
M22.
(a)
Third (generation) // 3;
R High Level Language
Do not reject high level language if answer also contains '3rd generation' –
refer upwards for anything else.
1
(b)
(i)
Hexadecimal // base 16;
A Hex
Hex used in textbook
1
(ii)
Take up less space when printing / viewing;
NE takes up less space
Less likely to make errors;
Op-codes are easier to recognize;
Easier to understand;
Less time taken when coding as more concise // quicker to program;
NE easier to read
NE quick to write
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Nottingham University Academy of Science and Technology
Max 1
(iii)
Lowest address : 00
Highest address : FF
BOTH correct to gain one mark;
A 0 for lowest address
A 255 for highest address
A notation in front of hex &, $
1
(c)
When coding for execution speed;
When coding to minimize object code size;
When writing code to control devices / directly access hardware;
A When coding for a specific processor;
A by example if maps to one of the above
Max 1
(d)
A compiler produces object code/machine code;
whilst an interpreter does not produce any object code;
Interpreted code will execute slower;
than executing the object code produced by a compiler;
You always need the interpreter to interpret source code;
but you do not need the compiler to execute a compiled program;
Once compiled source code is no longer required to run the program;
An interpreter always needs source code at runtime;
Compiled code can only be executed on a machine with the same processor
type / instruction set;
Interpreted code is more portable;
A compiler translates the whole source code (at once);
An interpreter analyses the code line by line;
NE reads
Max 4
[9]
M23.
(a)
X
Y;
A alternative notations:
X XOR Y
X EOR Y
X AND NOT Y OR NOT X AND Y
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Nottingham University Academy of Science and Technology
Acceptable notation for symbols :
For X.Y allow X∧Y, X∩Y, XY
For X+Y allow XvY,XUY
For X allow ~X
1
(b)
;
A alternative notations : X AND NOT Y;
1
(c)
(i)
Inputs
Outputs
X
Y
C
S
0
0
0
0
0
1
0
1
1
0
0
1
1
1
1
0
One mark for C column;
One mark for S column;
2
(ii)
Addition // adder;
A sum;
1
(d)
[Fully expanding brackets – 1 mark]
[Recognising X.X = X OR Y.
= 0 –1 mark]
[Taking X outside brackets – 1 mark]
X[Final Answer, 1 mark]
Alternative Answer : (Distributive)
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Nottingham University Academy of Science and Technology
[Use of distributive law – 1 mark]
[Recognising Y .
= 0 – 1 mark]
[ 1 mark ]
[Final Answer, 1 mark]
X+0=X
X
Alternative Answer : (De Morgan’s)
[Use of De Morgan’s – 1 mark]
[Two further applications of De
Morgan’s]
[Taking X outside brackets – 1 mark]
[Recognising ~Y + Y = 1 – 1 mark]
[Recognising X.1=X – 1 mark]
X=Q
[Final answer, 1 mark]
Max 3 for working/method;
1 for final answerX on own with no working gains 1 mark.
Max 4
[9]
M24.
(a)
General Purpose
Word Processor
Special
Purpose
Bespoke
✔
A✔
✔
Payroll
✔
Flight control
software
R Answers with more than one tick on a row.
3
(b)
1 – Operating System;
R OS, Operating Software
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Nottingham University Academy of Science and Technology
2 – Assembler / Compiler / Interpreter;
TO “assembly language”
3 – Backup / Anti virus / defragmenter / encryption / compression / archive /
system profilers / application launchers;
Accept any other examples of a utility
3
[6]
M25.
(a)
NAND
NOR
1
1
1
0
1
0
0;
0;
2
(b)
1 mark for NOT gates on both A and B;
1 mark for AND with inputs from
and ;
A inputs from A and B
1 mark for OR gate with inputs from AND gate output and C and output
connected to Z;
3
(c)
; ; 2 marks – 1 each for De Morgans rule for each side of the
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Nottingham University Academy of Science and Technology
central OR (award the mark for right hand expression, even if double NOT
over B is not cancelled)
Recognising NOT A OR NOT A is NOT A, and producing a correct
expression
+1; Recognising B or NOT B is 1
Final answer 1 ;
Alternative answer
; Application of De Morgan’s to entire expression
; Cancellation of NOTs; 1 mark – De Morgans on entire expression
Recognising A and A is A
Recognising B ANDed with its complement is 0
Recognising 0 AND anything is 0
Final answer 1 ;
Note: Marks can be awarded for the skills above if seen but Max 3 (out of 4)
for whole question if working has errors in it
A T, True for 1 and F, False for 0
A alternative notations :
•
For X.Y allow X AND Y, X ∧ Y,X∩Y, XY
•
For X+Y allow X OR Y, X v Y, X U Y
•
For
allow NOT X, ¬X
Or by truth table M = marking point
Max 3 for stages, 1 for final answer
4
[9]
M26.
(a)
Second (generation);
A2
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Nottingham University Academy of Science and Technology
R assembly code / language
Note: Adding “assembly” / “assembler” does not talk out a valid mark for
second / 2
1
(b)
(memory) Address / location / offset;
A line number
R instruction number
1
(c)
(y) Opcode / operation code;
A op-code
NE operation
(z) Operand;
2
(d)
Individual Instructions:
One to one / each assembly language instruction translates to one machine
code instruction;
Programs:
Figure 2 assembly language equivalent of figure 3 // figure 3 machine code
version of figure 2 // figure 3 is assembled version of figure 2;
NE figure 3 “binary version” of figure 2
NE different generations of language
1
[5]
M27.
(a)
Interactive OS:
User and computer in direct / two-way communication // User makes input to
computer then waits for output before making next input;
A system, software, program, OS for computer
Network OS:
(Layer of software that) redirects requests to remote resources; (A examples)
in a way that is transparent to user;
Must make one point about interactive and one point about network
Max 2
(b)
Flow of program/execution sequence determined by events // program
executes relevant code-handling block / procedure / sub-routine in response to
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Nottingham University Academy of Science and Technology
events;
Example of event such as clicking a button;
Message sent to program when event occurs;
System loop executes until application closes; this receives and processes
messages // use of event-listener/handler;
If several events occur they are queued;
Max 2
[4]
M28.
G
H
K
0
1
1
1
1
0
1
0
1
1
0
1
;
;
;
1 mark for each correct column
[3]
M29.
becomes A + B ;
A (A+B);
A A OR B;
B+ B. becomes B ;
A B+ A.
becomes A ;
A (B+1) becomes A ;
1 mark for each
[4]
M30.
(a)
System (software) / operating system;
R OS
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Nottingham University Academy of Science and Technology
A (device) driver
1
(b)
(i)
Software that can carry out many tasks// has many purposes/uses;
NE “many things” // “many functions” // “general purposes”
R for everyday use/tasks
1
(ii)
Word processor, spreadsheet, database, desktop publishing/DTP,
presentation or other suitable example;
R web browser // image/photo editor
1
(c)
(i)
(It is) immediately available;
A “off the shelf”
(It has a) lower cost as development costs shared amongst many;
NE cheaper
Wide range of training/support available;
Regular upgrades available;
Can hire staff with experience of package;
More likely to be bug-free as already in widespread use/“tested” by
many users;
A it has been “tried and tested”
R no bugs / tested more
Max 2
(ii)
No appropriate software to solve the problem exactly;
The only way to obtain software to do exactly/precisely what they want //
may need particular features not in special purpose software // will be
developed to match their needs;
To ensure competitors do not get access to the software;
To run on/support existing hardware/software;
No unnecessary features;
Max 1
[6]
M31.
(a)
Very hard/difficult to understand;
Very easy to make mistakes;
Hard to find any errors/mistakes in the code;
Time consuming to develop software in assembly language;
Lack of portability;
Lack of in-built functions/procedures;
NE harder to learn
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Nottingham University Academy of Science and Technology
Max 2
(b)
Compiler produces object code to distribute that is difficult to reverse
engineer/ no need to distribute the source code;
Compiler optimises the code // The object code /program runs faster (as it
does not need translating);
NE “Runs faster”, if not clear whether this applies to the program or the
compiler.
The target computer has no need to have the original compiler;
Object code can be installed on target computer;
No interpreter available for target machine;
2
[4]
M32.
Good at:
Can make precise/accurate / complex calculations / actions;
NE “good at maths / logic” – need the concept of complex
More consistent than humans;
Repetitive tasks;
Can work in conditions too dangerous for a human;
Working with large volumes of data;
Fast processing of data / calculations;
Can perform task without breaks / / for longer than humans;
R don’t get bored
Bad at:
Image recognition;
Shape detection;
If the conditions change they adapt poorly / / not very adaptable / / learning;
A “can’t think for themselves”
Poor at coping with emergencies / unexpected circumstances;
Creativity / / invention / / lateral thinking;
Bad at discriminating;
Processing qualitative data;
Recognising human concepts e.g. emotion;
A Cannot recognise when it makes mistakes;
Above are exemplars only. Award credit for other valid points.
Max 3 if all points are about just good or just bad.
[4]
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Nottingham University Academy of Science and Technology
M33.
(a)
(i)
Hardware: Electrical/physical components/parts/circuits of the
computer;
R Examples
R Just components/parts NE
R Physical device NE
R System
1
(ii)
Software: Programs / sequences / series of instructions which run /
execute (on) the hardware / computer ;
R Examples only
R Application NE
R Code NE
1
(b)
1. Special Purpose (software); A Specialist / Specific purpose (software)
2. General Purpose (software);
3. System Software; A Systems Software
4. Utilities;
4
[6]
M34.
(a)
Number
Component Name
1
Memory Address Register
2
Address Bus
3
Memory Data / Buffer Register
4
Data Bus
4
(b)
The instruction is held in the CIR;
A IR
The control unit / instruction decoder decodes the instruction;
The opcode identifies the type of instruction it is;
Relevant part of CPU / processor executes instruction;
A ALU
Further memory fetches / saves carried out if required;
Result of computation stored in accumulator / register / written to main
memory;
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Nottingham University Academy of Science and Technology
Status register updated;
If jump / branch instruction, PC is updated;
A SCR
Max 3
(c)
Can be displayed in less space;
R takes up less space NE
Easier to remember / learn / read / understand;
Less error prone;
Max 1
(d)
(i)
Assembler;
1
(ii)
HLLs are problem oriented;
HLL programs are portable // machine / platform independent ;
English like keywords / commands/ syntax / code;
R closer to English
Less code required // less tedious to program //
one to many mapping of HLL statements to machine code commands;
Quicker/easier to understand / write / debug /learn / maintain code;
R just quicker/easier
HLLs offer extra features e.g. data types / structures // structured
statements // local variables // parameters // named variables/constants;
R procedures / modular
A example of a data structure
NE “extra features” without example
Speed of execution not crucial for most tasks so faster execution of
assembly language not required;
Most computer systems have a lot of (main) memory / RAM so compact
object code not essential;
A converse points for Assembly Language
3
[12]
M35.
(a)
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Nottingham University Academy of Science and Technology
1 mark for each correct output column
A True for 1, False for 0
2
(b)
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Nottingham University Academy of Science and Technology
1 mark for NOT gate correctly linked to input C;
1 mark for AND gate correctly linked to B and
as input;
A if AND gate linked directly to C
1 mark for OR gate with inputs from A and the output of an AND gate and
output connected to Q;
3
(c)
Algebraic solution:
B.( A +
)
B.A + B.
[1 mark for expansion of brackets ]
B.A + 0
[1 mark for identifying that B. = 0 ]
B.A
[1 mark for correct answer]
Truth table solution:
1 mark for both columns X and Y correct
1 mark for column Z correct
1 mark for correct answer (B.A)
Any other method:
If student has used any other method to arrive at correct answer then award
marks as follows:
1 mark for correct answer, no working out
2 marks for correct answer with working out, not all steps shown.
3 marks for correct answer with all steps of working out shown.
A True for 1, False for 0
A alternative notations :
•
For X.Y allow X AND Y, X∧Y ,X∩Y, XY
•
For X+Y allow X OR Y, X∨Y , XUY
•
For
allow NOT X, ¬X
3
[8]
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Nottingham University Academy of Science and Technology
M36.
(a)
To hide the complexities of the hardware from the user // Provision of virtual
machine;
R Provision of user interface NE
A machine for hardware but R system, computer
Manages the hardware (resources) // allocation of hardware resources (to
processes);
A Examples of resources
2
(b)
Subject-related points:
Desktop computer used for many different/generic purposes; so ...
•
desktop OS must support a wide range of peripherals/storage devices;
•
desktop OS must run wide range of software/packages;
•
desktop OS more customisable (by user);
•
desktop OS must manage security;
Desktop computer requirements more likely to change over time // more likely
to want to add new features/support new applications; so....
•
desktop OS has modular design / easier to upgrade;
Desktop computers made by many different manufacturers // to varying
specifications; so....
•
desktop OS must run on wider range of hardware platforms;
Desktop computer more likely to be networked; so...
•
desktop OS must support networking protocols;
Embedded systems (often) made at low cost // may have minimal processing
requirement; so...
•
embedded system OS has lower hardware requirements (allow e.g.
such as slower processor, less RAM);
Embedded systems have few inputs and outputs to user; so...
•
embedded system OS provides no/minimal user interface;
•
embedded system OS designed to deal with input from sensors // output
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Nottingham University Academy of Science and Technology
to control devices;
Embedded systems (often) in battery powered devices; so
•
managing power consumption particularly important; A example of
power management
Embedded systems (are sometimes) real-time // for safety-critical applications;
so...
•
real-time embedded system OS must be designed to guarantee speed
of response // respond very quickly;*
•
real-time embedded system OS must deal with many inputs
simultaneously;*
•
real-time embedded system OS may need to be failsafe;*
•
real-time embedded system OS may incorporate redundancy;*
* - These points only valid if real-time system specifically referenced.
A any mix of points. The reason does not have to be stated to award a mark
for the difference/feature.
A converse of the points if the point itself has not been given.
To achieve a mark in this band, candidates must meet the subject criterion
(SUB) and 4 of the 5 quality of written communication criteria (QWCx).
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate has made three or more relevant points.
Text is legible
There are few, if any, errors of spelling, punctuation and grammar. Meaning
is clear.
The candidate has selected and used a form and style of writing appropriate
to the purpose and has expressed ideas clearly and fluently.
Sentences and paragraphs follow on from one another clearly and
coherently.
Appropriate specialist vocabulary has been used.
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Nottingham University Academy of Science and Technology
3–4
To achieve a mark in this band, candidates must meet the subject criterion
(SUB) and 4 of the 5 quality of written communication criteria (QWCx).
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate has made two relevant points.
Text is legible
There may be occasional errors of spelling, punctuation and grammar.
Meaning is clear.
The candidate has, in the main, used a form and style of writing appropriate
to the purpose, with occasional lapses. The candidate has expressed ideas
clearly and reasonably fluently.
The candidate has used well-linked sentences and paragraphs.
Appropriate specialist vocabulary has been used.
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Nottingham University Academy of Science and Technology
2
To achieve a mark in this band, candidates must meet the subject criterion
(SUB). The quality of written communication should be typified by the QWCx
statements.
SUB
QWC1
QWC2
QWC3
QWC4
QWC5
Candidate has made just one relevant point.
Most of the text is legible.
There may be some errors of spelling, punctuation and grammar but it
should still be possible to understand most of the response.
The candidate has used a form and style of writing which has many
deficiencies. Ideas are not always clearly expressed.
Sentences and paragraphs may not always be well-connected or bullet
points may have been used.
Specialist vocabulary has been used inappropriately or not at all.
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Nottingham University Academy of Science and Technology
1
Candidate has made no relevant points.
0
Note: Even if English is perfect, candidates can only get marks for the points
made at the top of the mark scheme for this question.
If a candidate meets the subject criterion in a band but does not meet the
quality of written communication criteria then drop mark by one band,
providing that at least 3 of the quality of written communication criteria are met
in the lower band. If 3 criteria are not met then drop by two bands.
4
[6]
M37.
Algebraic Solution:
Method 1
Method 2
+A
=
+
+A
+A
=
=1+
=
=1
=
=1
1 mark for an application of a DeMorgan’s law
1 mark for realisation that A +
+
=1+
or
=
(must be written in
method, not just inferred that student has done this if arrives at correct answer)
1 mark for correct answer
Truth table solution:
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Nottingham University Academy of Science and Technology
1 mark for column Y correct
1 mark for column Z correct
1 mark for correct answer
Any other method:
If student has used any other method to arrive at correct answer then award marks
as follows:
1 mark for correct answer, no working out
2 marks for correct answer with working out, not all steps shown.
3 marks for correct answer with all steps of working out shown.
A True for 1, False for 0
A alternative notations :
•
For X.Y allow X AND Y, X∧Y ,X∩Y, XY
•
For X+Y allow X OR Y, X∨Y , X∪Y
•
For
allow NOT X, ¬X
[3]
M38.
(a)
So that source code cannot be accessed by users;
Users do not need to have an interpreter / compiler / translator // users do not
need programming environment;
Users do not need knowledge of the programming environment;
So that the program will execute more quickly;
NE it’s faster
NE does not need to be compiled each time executed/run
R saves disk space
Max 2
(b)
Can’t know what type of processor will be in user’s computer // Internet users
have range of computers / devices with different processors;
A compiled program will only execute on a processor of specific type / family /
with same instruction set//A program run using an interpreter can execute on a
computer with any type of processor;
A References to just different types of computer / device rather than
specifically processors
NB Virtual Machine
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Nottingham University Academy of Science and Technology
R No compiler exists
R computers may have different web browsers/software
2
[4]
M39.
(a)
OS hides complexities of hardware from the user;
1
(b)
Any three @ 1 each
Processor(s)/cpu(s);
Memory/IAS/Main memory;
Disk (space)/backing store; A Hard disk/drive //Floppy disk (drive)//
Secondary storage
I/O devices//peripherals; R examples
File space;
A files
R data
R programs
Max 3
[4]
M40.
NO PRODUCT NAMES
(a)
(i)
Physical/electrical/electronic components/parts/devices/circuits (of the
computer);
R things you can touch R actual components R examples (questions
asks for meaning of)
R physical machinery connected to computer (t.o.)
Max 1
(ii)
Programs (which run on the computer/hardware); sequences of
instructions /codes;
Max 1
(b)
(i)
R what runs on computer
layer of software which enables users to operate computer; interface
between user and computer software which allows user to communicate
with / manage hardware; software to run
applications/hardware/programs/computer/packages; software to make
computer/hardware work / used to maintain hardware;
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Nottingham University Academy of Science and Technology
A operating system;
R platform
R software used to run the system / it
Max 1
(ii)
Operating system (if not given in (i));utility programs / library programs /
compilers/ assembler / interpreter / file manager / bootstrap loader /
hardware driver / BIOS / spooler / communication software / device
manager / memory management / GUI / screen saver; R kernel or an
example of a utility program; eg defragmenter; compression software;
text editor; virus checker;
NO PRODUCT NAMES: R winzip / notepad etc
Max 1
(iii)
Application Software; bespoke software;
A generic software;
R generic system R dedicated package R utility program
R general purpose software
R off the shelf software R any type of system software word processor /
spreadsheet / DTP / Game /image processing software;
A browser any suitable bespoke example e.g. payroll;
R integrated package
No link between (iii) and (iv) i.e. no follow through
[6]
M41.
(a)
(i)
Assembler;
1
(ii)
Interpreter / compiler;
Max 1
(b)
Problem oriented;
Portable; machine independent;
One-to-many mapping of HLL statement to machine code statement;
Datatypes; structured statements; local variables; parameters; data structures;
A example of a datastructure;
Named variables; named constants; English-like keywords/commands;
Quick/easy to understand / write / debug / learn / maintain;
R quick/ easy to use
R modular
R procedures
R takes longer to translate
R closer to English
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Nottingham University Academy of Science and Technology
Max 2
(c)
Easier to understand / more transparent; less error prone; easier to maintain /
change (if the value changes);
Allow by example
eg if VAT rate changes only need to change value in declaration
Max 1
(d)
(i)
Accept any imperative HLL such as Pascal/VB/C/C++/PL1/Cobol;
SEE TABLE FOR DIFFERENT LANGUAGE EXAMPLES FOR (ii) & (iii)
Ignore line breaks in statements
1
(ii)
1 mark for correct key words in correct order (shown in bold in table
overleaf); 1 mark for correct Boolean expression / loop control
expression ;
2
(iii)
1 mark for correct key words in correct order (shown in bold in table
overleaf); 1 mark for correct boolean expression;
2
If (i) does not match (ii) and (iii) do not give marks for (ii) and (iii)
If candidate names a language you are not familiar with, contact your
team leader
Language
Pascal
Delphi
Kylix
Visual
Basic
VSScript
Bool
expr
a>b
a=b
a< >b
a<b
a>=b
a<=b
Iteration
....are possible statements(ignore)
FOR <variable>:= <value1> TO
<value2> DO ......
REPEAT ......
UNTIL <bool expr>
WHILE <bool expr>
DO .....
a>b
a=b
a< >b
a<b
a>=b
a<=b
FOR <variable> = <value 1> TO
<value2>
.....
NEXT
DO WHILE/UNTIL <bool expr>
.....LOOP
DO .....
LOOP UNTIL/WHILE <bool expr>
WHILE <bool expr> .....
WEND
Page 113
Selection
....are possible statements(ignore)
IF <bool expr> THEN ......
else part optional
CASE <variable> OF
<value1>.....
<value2>......
ENDCASE
else part optional.
No of values can vary
IF <bool expr> THEN
.....
END IF
Else part optional
SELECT CASE <variable>
CASE <value1>
.....
CASE <value2>
.....
End Selct
Else part optional
Nottingham University Academy of Science and Technology
C/C++
Java
Javascript
COBOL
Fortran
Basic
a>b
a==b
a!=b
a<b
a>=b
a<=b
a>b
a=b
a< >b
a<b
a>=b
a<=b
a.LT.b
a.GE.b
a.LE.b
a.GT.b
a.NE.b
a.EQ.b
a>b
a=b
a< >b
a<b
a>=b
a<=b
FOR (<initialisation>; <condition>;
<increment>).....
WHILE (bool expr) DO ....
No of CASE values can vary
IF (bool expr) { }
Else part optional
SWITCH (
) {CASE <value>:
BREAK}
No of CASE values can vary
PERFORM .....<number> TIMES
PERFORM VARYING
<variable> FROM <value>BY
<value> UNTIL <bool expr using
variable>
IF <bool expr> PERFORM ......
Else part optional
DO <number> < variable>=
<init value> <final value>
step value optional
IF <bool expr> .....
IF (<arithmetic expr>) label1,
label2, label3
FOR <variable> = <start value> TO
<stop value>
....
NEXT <variable>
step value optional
REPEAT
....
UNTIL <bool expr>
IF <bool expr> THEN ......
GOTO label1, label2, label3
DEPENDING ON <variable>
2
[10]
M42.
(a)
(i)
(Data/address/control/internal/system) bus;
R just a description of a bus
R names of buses which don’t exist e.g. memory bus
1
(ii)
Store programs and/or data/files when not in use/
When computer is off permanent/long term storage
Of programs and/or data; save programs/data;
R offline/backup R ROM R temporary storage
A save on magnetic disk/ tape storage;
A information instead of data
1
(iii)
(Machine code) instruction/data is fetched from main memory;
A what is fetched or from where
Instruction is decoded;
Instruction is executed (by the processor); R data executed
Max 2
(b)
(i)
Assembly language; mnemonic code; mnemonics; assembly code;
R low level language A assembler;
1
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Nottingham University Academy of Science and Technology
(ii)
Translated/assembled/converted/decoded; into machine code
(instructions);
R compiled R interpreted A object/target code;
A binary instructions;
2
(iii)
Computer executes instructions in programmer defined sequence;
A the programmer tells the computer how to do it;
R user instead of programmer
1
(iv)
Pascal /Visual
Basic/Basic/C/C++/Cobol/Fortran/Ada/Delphi/Lylix/Modula /or any other
imperative HLL
R Prolog
R Lisp
R Pop11
1
(v)
One statement/instruction/command in a high level language translates
into several machine code instructions; 1 to many;
1
(vi)
Laborious/time-consuming to write; hard to debug; harder to program;
easier to make mistakes; more difficult to understand/ learn; difficult to
maintain; different assembler/instruction set for different type of
computer; machine dependent; low level programs not portable;
Max 2
[12]
M43.
(a)
Easier maintenance/upgradeable; can get an overview of system;
Quicker to write/Easier development; can break problem down into sub tasks/
can re–use modules/ distribute among team;
R easier to read so can get a team to write program;
More systematic testing; can test a module at a time;
Fewer mistakes made; clear organisation of code;
Quicker/easier to debug; easier to see where errors are;
Fewer lines of code using subroutines; code not duplicated;
(1 mark for reason, 1 mark for explanation
OR 2 marks for good explanation per point)
Max 4
(b)
Structured statements such as iteration / selection;
Use of Procedures / functions/subroutines/modules/libraries;
User defined data types; built–in data types; Data structures;
Can choose sensible names for identifiers;
English–like keywords / constructs; Indentation; Comments;
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Nottingham University Academy of Science and Technology
Use of local variables; parameters; named constants;
R closer to natural language/ almost written in English
R machine independent / problem oriented / top–down
Max 3
(c)
Compiler translates whole source code into object/machine/runnable code /
exe file;
Compiled program runs faster than interpreted program;
Interpreter translates line by line as it executes/is running;
Interpreter must be in memory to execute program; compiler only needed
during translation stage, not during execution of program.;
interpreter runs one line at a time;
Max 2
[9]
M44.
(a)
System software / program which controls the computer hardware;
Manages computer (system) / hardware;
Interface between user and computer;
Runs programs; handles input/output;
Max 1
(b)
(i)
Executes instructions/programs/code; R data
Performs calculations/instructions
R controls…
R processes…
1
(ii)
Stores/holds program /instructions / data;
R permanently
R files
1
(c)
Data bus; (1)
carries the data/instructions to/from component; R holds Address bus; (1)
carries identification/address about where the data is being sent to /fetched
from; R holds (1)
Control bus; (1)
to send control signals; whether process is read or write; (1)
carries timing signal;
R holds
R controls flow of data
1 mark for name 1 mark for example × 3
6
[9]
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Nottingham University Academy of Science and Technology
M45.
(a)
(i)
Layer of software which enables users to operate computer; software to
make hardware work; operating system;
Max 1
(ii)
Program written to perform end user task; problem-oriented program to
enable user to do specific task; program produced by end use;
Max 1
(b)
(i)
Operating system / utility programs / library programs / compilers / assembler
/ interpreter;
1
(ii)
Word processor / DTP / Spreadsheet / Database / stock control / payroll
/ web browser / or other suitable
1
[4]
M46.
(a)
(i)
Machine code language / machine language;
R binary code / binary language
1
(ii)
Assembly language;
A assembly code / mnemonic code;
R low level language
1
(b)
Pascal / Basic / Visual Basic / Fortran / Cobol (or similar)
R any Markup language
1
[3]
M47.
(a)
2 each for any feature of a LLL, contrasted with the corresponding feature of a
HLL, eg processor dependence / processor independence machine-oriented /
task oriented 1-to-1 / 1 -to-many correspondence source / object code
translation is by assembler / compiler respectively should be at least two
aspects contrasted
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Nottingham University Academy of Science and Technology
4
(b)
Where either program size or execution speed is critical, or precise timing
needed, eg o/s kernel, device driver, real-time control, comms systems, or if
direct control of the way a program functions is a requirement, etc
Can award 1 if situation is simply named
2
[6]
M48.
(a)
Can run just a part of the program so easier to find problems.
Do not have to keep re–compiling the whole program when correcting errors
Any 1 × 1
1
(b)
Produces complete object code / executable version
No need to install language to run the program / needs less memory
Runs faster as no time wasted on translation.
User cannot change source code
Any 2 × 1
2
[3]
M49.
Assembler:
To translate an assembly (low level) language routine or program;
One to one translation;
Assembler is m/c specific;
Compiler:
To translate a HLL program;
One to many translation;
Has many options / stages;
Language specific;
For each, two statements to distinguish 1 mark each
Max 4
[4]
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Nottingham University Academy of Science and Technology
M50.
(a)
A server provides services required by client computer/workstation/
terminal/client application (NOT USER, NOT CLIENT on its own); such as
printing, file/data storage, file server, communications-e-mail server, Web
access server, Internet server, ISP, database, controlling logging in; (any one
example providing services required by.)
2
(b)
Any 4 points × 1
No marks for a point which references just data when it should reference a
program.
Backing store is NOT acceptable as a substitute for disk (must be a direct
access device)
Accept partitions as a substitute for pages (but NOT portions)
A memory management technique;
Transparent to the user/programmer which permits;
The execution of a process/processes where the total virtual address space
exceeds the physical MAIN memory capacity;
Execution of a program which is not entirely in main memory/less than the full
virtual address space of a process resident in physical memory/ execution of
partially loaded processes/lets user think there is more main memory/RAM;
Disk is used as RAM;
Physical memory is conceptually divided into a number of fixed size
pages/segments;
The virtual address space of a program/process is divided into a number of
fixed size pages;
Page table indicates which pages of a process are loaded and where;
The program and data reside on disk and are swapped into memory and out
of memory as required.(DISK THRASHING);
NB Allow an answer which uses segmentation. No marks for answers
describing overlay techniques
NOT computer fooled into thinking more main memory
Max 4
[6]
M51.
(a)
Software which carries out tasks which aid the functioning of the computer, as
Page 119
Nottingham University Academy of Science and Technology
opposed to user tasks or applications
1
(b)
Any two suitable examples, e.g.
Operating System (accept Windows or Unix, but not both)
File manager
ScanDisk or other disk manager
Defragmenter
Formatter
Disk copier
Backup / Restore utility
Virus checker
Peripheral driver
NOT compiler etc (language systems are not system s/w)
Etc – examples must be distinct
NOT utilities (too vague)
1 mark each × 2
2
[3]
M52.
(a)
Set of rules for syntax / semantics / grammar for writing sets of instructions to
be run on a computer
2
(b)
Low-level is oriented towards a particular processor (1), high-level towards a
problem type (1).
Accept: low-level requires knowledge of machine architecture (1), whereas
high-level is machine-independent (1) or low-level has one-to-one
correspondence with machine code instructions (1), high-level is one-to-many
(1) or machine-oriented (l/l) s. human-oriented (h/l) no credit for naming
languages
2
(c)
Program needs to be translated (accept compiled, assembled or interpreted)
(1) into machine code computer can only execute machine code (1)
2
[6]
Page 120
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