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CS 161
INTRO TO PROGRAMMING I
Dr. Blaise W. Liffick
Fall 2014
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Programming
Techniques
Languages
Problem Analysis
Program Design
•Algorithms & Design Patterns
•Data Structures
Paradigms
Java
C++
Hardware
Network
Linux
Eclipse
Programming
Environments
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Early Computers
• Late 1930’s, John Atanasoff, Clifford Berry
• ENIAC
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1946
University of Pennsylvania
J. Presper Eckert and John Mauchley
John von Neumann, stored-program concept
and use of binary
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Categories of Computers
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Supercomputers
Mainframe
Minicomputers
Microcomputers
Mobile devices
Power
Size
Cost
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Computer Hardware
• CPU - central processing unit
– Where decisions are made, computations are
performed, and input/output requests are
delegated
• Main Memory
– Stores information being processed by the CPU
• Secondary Memory (Mass Storage)
– Stores data and programs
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Computer Hardware
• Input devices
– Allow people to supply information to
computers
• Output devices
– Allow people to receive information from
computers
• Peripheral Devices
– Generally I/O, mass storage
• Network connection
– Modems
– Ethernet interface
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Figure 1.2
Computer components
Mass storage
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CPU
• “Brains” of the computer
– Arithmetic calculations are performed using the
Arithmetic/Logical Unit or ALU
– Control unit decodes and executes instructions
– Registers hold information and instructions for
CPU to process
• Arithmetic operations are performed using
binary number system
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Memory
• Stores
– programs
• operating system
• applications
– data
• Types
– RAM - volatile
– ROM
• Composed of bits, which are combined into
bytes
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Memory Cells
Address Contents
0
1
2
3
-27.2
354
0.005
-26
4
5
6
H
RTV 001
...
...
999
X
75.62
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Input / Output Devices
• Accessories that allow computer to perform
specific tasks
– Receiving information for processing
– Return the results of processing
• Common input and output devices
– Keyboard
– Printer
Joystick
Monitor
Scanner
Speaker
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Computer Networks
• Allows multiple computers to connect
together to share resources and/or data
• LAN - Local area network
– Organizational
• WAN - Wide area network
– Internet
• Requires additional hardware
– modem
– network interface
– servers
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The “Cloud”
• Wireless access
– WiFi
– Cell
• Servers
– Storage
– Applications
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World Wide Web
• Introduced 1989
• Developed by CERN
– European Laboratory for Particle Physics
• Web browser - GUI
– Netscape
– IE
– Firefox
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1.3 Computer Software
• Operating system
• Other system software
– utilities
– programming language systems
• Applications
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Operating System
• E.g. Windows®, Linux, Mac OS X, Unix®
• Controls
– the interaction of system with the user
– hardware interactions
• Part is usually stored on ROM, rest on hard
drive
– This arrangement requires booting the system
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Some OS Responsibilities
• Communicating with the user; receiving
user commands
• Managing allocation of memory, processor
time, file system, and other resources
• Collecting input from keyboard, mouse, etc.
• Conveying output to screen, printer, etc.
• Writing data to secondary storage devices
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Application Software
• Does the “real” work
• Common application software
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Word processors
Desktop publishing programs
Spreadsheets
Presentation managers
Drawing programs
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Programming Languages
• Machine Language
– Most fundamental language of the computer
– Unique for each processor type
– Binary 0s and 1s that specify what to do
• 0010 0000 0000 0100
• 1000 0000 0000 0101
• 0011 0000 0000 0110
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Table 1.2
A Program in Machine and Assembly
Language
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High - Level Languages
• Resemble human language
– Java, C++, C, Pascal, FORTRAN, Ada
a = a + b;
• More compact and human understandable
than machine language
• Must be translated into machine language
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1.4 Processing a High-Level
Language Program
• Set of programs used to develop software
• A key component is a translator
– Compiler
• Examples
– Java, g++, Microsoft Visual C++®
• Other programs needed
– Editor
– Linker
– Loader
IDE
(e.g. Eclipse)
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Processing a Program
• Editor used to enter the program
– Like minimal word processor
– Creates source program file
• Compiler translates the source program
– Displays syntax errors
– Creates (usually) temporary object code file
• Linker/Loader to combine object file with
other object files and execute program
– Creates final executable program
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Executing a Program
• CPU
– examines each program instruction in memory
– sends out command signals required to carry
out the instruction
• Special instructions used to
– input data into memory for the program to use
– output data to display or printer (or other
device)
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Editor used to
create program
Source File
Compiler
translates
program into
machine
language
Java
.java
successful
unsuccessful
Error Messages
Other Object
Files
Byte Codes
.class
Java Runtime
Environment
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1.5 Software Development
Method
1. Problem Analysis
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Identify data objects
Determine Input / Output data
Constraints on the problem
2. Design
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Decompose into smaller problems
Top-down design (divide and conquer)
Develop Algorithm (Desk check)
•
Algorithm refinement
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Software Development Method
3. Implementation
Converting the algorithm into programming
language
4. Testing
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Verify the program meets requirements
System and Unit test
5. Maintenance
–
All programs undergo change over time
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