Download Assembly Language for Intel-Based Computers, 5th Edition Chapter 1

Assembly Language for Intel-Based
Computers, 5th Edition
Kip Irvine
Chapter 1: Basic Concepts
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Revision date: June 3, 2006
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Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Chapter 1 Overview
• 1.1 Welcome to Assembly Language
• 1.2 Virtual Machine Concept
• 1.3 Data Representation
• 1.4 Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.1 Welcome to Assembly Language
• 1.1.1 Some Good Questions to Ask
• 1.1.2 Assembly Language Applications
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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2.1.1 Questions to Ask
• What is an assembler?
•A program that converts source-code programs from
assembly language into machine language
•MASM (Microsoft Assembler), TASM (Borland Turbo
Assembler)
• Linker (a companion program of Assembler)
combines individual files created by an assembler
into a single executable program.
• Debugger provides a way for a programmer to trace
the execution of a program and examine the contents
of memory.
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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2.1.1 Questions to Ask (cont)
• What hardware/software do I need?
• A computer with an Intel386, Intel486 or one of the Pentium
processors (IA-32 processor family)
• OS: Microsoft Windows, MS-DOS, LINUX running a DOS
emulator
• Editor
• Assembler
• Linker (Microsoft 16-bit linker: LINK.EXE, 32-bit linker:
LINK32.EXE),
• Debugger (16-bit MS-DOS programs: MASM CodeView, TASM
Turbo Debugger. 32-bit Windows console programs: Microsoft
Visual Studio –msdev.exe
• What types of programs will I create?
• 16-Bit Real-Address Mode: MS-DOS, DOS emulator
• 32-Bit Protected Mode: Microsoft Windows
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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2.1.1 Questions to Ask (cont)
• How does assembly language (AL) relate to machine
language?
•One-to-one relationship
• How do C++ and Java relate to AL?
•E.g., X=(Y+4) *3
• Is AL portable?
•A language whose source program can be compiled
and run on a wide variety of computer systems is said
to be portable.
•AL makes no attempt to be portable.
•It is tied to a specific processor family
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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2.1.1 Questions to Ask (cont)
• Why learn AL?
•Embedded system programs
•Programs to be highly optimized for both space and
runtime speed
•To gain an overall understanding of the interaction
between the hardware, OS and application programs
•Device driver: programs that translate general
operating system commands into specific references to
hardware details
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.1.2 Assembly Language Applications
• Some representative types of applications:
•Business application for single platform
•Hardware device driver
•Business application for multiple platforms
•Embedded systems & computer games
(see next panel)
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Comparing ASM to High-Level Languages
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Chapter 1 Overview: What’
s Next
• 1.1 Welcome to Assembly Language
• 1.2 Virtual Machine Concept
• 1.3 Data Representation
• 1.4 Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.2 Virtual Machine Concept
• Virtual Machines
• Specific Machine Levels
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.2 Virtual Machines
• Virtual machine concept
• In terms of programming Language :
• Each computer has a native machine language (language L0)
that runs directly on its hardware
• A more human-friendly language is usually constructed
above machine language, called Language L1
• Programs written in L1 can run two different ways:
• Interpretation –L0 program interprets and executes L1
instructions one by one
• Translation –L1 program is completely translated into an
L0 program, which then runs on the computer hardware
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.2 Virtual Machines (Cont.)
• In terms of a hypothetical computer
• VM1 can execute commands written in language L1.
• VM2 can execute commands written in language L2.
• The process can repeat until a virtual machine VMn can be
designed that supports a powerful, easy-to-use language
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Translating Languages
English: Display the sum of A times B plus C.
C++: cout << (A * B + C);
Assembly Language:
Intel Machine Language:
mov eax,A
mul B
add eax,C
call WriteInt
A1 00000000
F7 25 00000004
03 05 00000008
E8 00500000
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Specific Machine Levels
High-Level Language
Level 5
Assembly Language
Level 4
Operating System
Level 3
Instruction Set
Architecture
Level 2
Microarchitecture
Level 1
Digital Logic
Level 0
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
(descriptions of individual levels
follow . . . )
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Digital Logic
• Level 0
• CPU, constructed from digital logic gates
• System bus
• Memory
• Implemented using bipolar transistors
next: Data Representation
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Microarchitecture
• Level 1
• Interprets conventional machine
instructions (Level 2)
• Executed by digital hardware (Level 0)
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Instruction Set Architecture
• Level 2
• Also known as conventional machine language
• Executed by Level 1 (microarchitecture)
program
•Each machine-language instruction is executed
by several microinstructions
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Operating System
• Level 3
• Provides services to Level 4 programs
• Translated and run at the instruction set
architecture level (Level 2)
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Assembly Language
• Level 4
• Instruction mnemonics such as ADD, SUB and
MOV that are easily translated to the instruction
set architecture level (Level 2)
• Calls functions written at the operating system
level (Level 3)
• Programs are translated into machine language
(Level 2)
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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High-Level Language
• Level 5
• Application-oriented languages
•C++, Java, Pascal, Visual Basic . . .
• Programs compile into assembly language
(Level 4)
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Chapter 1 Overview: What’
s Next
• 1.1 Welcome to Assembly Language
• 1.2 Virtual Machine Concept
• 1.3 Data Representation
• 1.4 Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3 Data Representation
• 1.3.1 Binary Numbers
•Translating between binary and decimal
• 1.3.2 Binary Addition
• 1.3.3 Integer Storage Sizes
• 1.3.4 Hexadecimal Integers
•Translating between decimal and hexadecimal
•Hexadecimal subtraction
• 1.3.5 Signed Integers
•Binary subtraction
• 1.3.6 Character Storage
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.1 Binary Numbers
• Digits are 1 and 0
•1 = true
•0 = false
• MSB –most significant bit
• LSB –least significant bit
MSB
• Bit numbering:
LSB
1011001010011100
15
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Binary Numbers (cont.)
• Each digit (bit) is either 1 or 0
• Each bit represents a power of 2:
1
1
1
1
1
1
1
1
27
26
25
24
23
22
21
20
Every binary
number is a
sum of powers
of 2
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Translating Binary to Decimal
Weighted positional notation shows how to calculate the
decimal value of each binary bit:
dec = (Dn-1 2n-1) (Dn-2 2n-2) ... (D1 21) (D0 20)
D = binary digit
binary 00001001 = decimal 9:
(1 23) + (1 20) = 9
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Translating Unsigned Decimal to Binary
• Repeatedly divide the decimal integer by 2. Each
remainder is a binary digit in the translated value:
37 = 100101
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.2 Binary Addition
• Starting with the LSB, add each pair of digits, include
the carry if present.
+
bit position:
carry:
1
0
0
0
0
0
1
0
0
(4)
0
0
0
0
0
1
1
1
(7)
0
0
0
0
1
0
1
1
(11)
7
6
5
4
3
2
1
0
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.3 Integer Storage Sizes
byte
Standard sizes:
word
doubleword
quadword
8
16
32
64
What is the largest unsigned integer that may be stored in 20 bits?
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.4 Hexadecimal Integers
Binary values are represented in hexadecimal.
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Translating Binary to Hexadecimal
•Each hexadecimal digit corresponds to 4 binary bits.
•Example: Translate the binary integer
000101101010011110010100 to hexadecimal:
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Converting Hexadecimal to Decimal
• Multiply each digit by its corresponding power of 16:
dec = (D3 163) + (D2 162) + (D1 161) + (D0 160)
• Hex 1234 equals (1 163) + (2 162) + (3 161) + (4 160), or
decimal 4,660.
• Hex 3BA4 equals (3 163) + (11 * 162) + (10 161) + (4 160), or
decimal 15,268.
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Powers of 16
Used when calculating hexadecimal values up to 8 digits
long:
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Converting Decimal to Hexadecimal
decimal 422 = 1A6 hexadecimal
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Hexadecimal Addition
• Divide the sum of two digits by the number base (16). The quotient
becomes the carry value, and the remainder is the sum digit.
36
42
78
28
45
6D
1
1
28
58
80
6A
4B
B5
21 / 16 = 1, rem 5
Important skill: Programmers frequently add and subtract the
addresses of variables and instructions.
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Hexadecimal Subtraction
• When a borrow is required from the digit to the left, add 16
(decimal) to the current digit's value:
16 + 5 = 21
1
C6
A2
24
75
47
2E
Practice: The address of var1 is 00400020. The address of the next
variable after var1 is 0040006A. How many bytes are used by var1?
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.5 Signed Integers
The highest bit indicates the sign. 1 = negative,
0 = positive
sign bit
1
1
1
1
0
1
1
0
0
0
0
0
1
0
1
0
Negative
Positive
If the highest digit of a hexadecimal integer is > 7, the value is
negative. Examples: 8A, C5, A2, 9D
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Forming the Two's Complement
• Negative numbers are stored in two's complement
notation
• Represents the additive Inverse
Note that 00000001 + 11111111 = 00000000
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Binary Subtraction
• When subtracting A –B, convert B to its two's
complement
• Add A to (–B)
00001100
–0 0 0 0 0 0 1 1
00001100
11111101
00001001
Practice: Subtract 0101 from 1001.
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Learn How To Do the Following:
• Form the two's complement of a hexadecimal integer
• Convert signed binary to decimal
• Convert signed decimal to binary
• Convert signed decimal to hexadecimal
• Convert signed hexadecimal to decimal
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Ranges of Signed Integers
The highest bit is reserved for the sign. This limits the range:
Practice: What is the largest positive value that may be stored in 20 bits?
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.3.6 Character Storage
• Character sets
•Standard ASCII (0 –127)
•Extended ASCII (0 –255)
•ANSI (0 –255)
•Unicode (0 –65,535)
• Null-terminated String
•Array of characters followed by a null byte
• Using the ASCII table
•back inside cover of book
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Numeric Data Representation
• pure binary
•can be calculated directly
• ASCII binary
•string of digits: "01010101"
• ASCII decimal
•string of digits: "65"
• ASCII hexadecimal
•string of digits: "9C"
next: Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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Chapter 1 Overview: What's Next
• 1.1 Welcome to Assembly Language
• 1.2 Virtual Machine Concept
• 1.3 Data Representation
• 1.4 Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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1.4 Boolean Operations
• NOT
• AND
• OR
• Operator Precedence
• Truth Tables
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Boolean Algebra
• Based on symbolic logic, designed by George Boole
• Boolean expressions created from:
•NOT, AND, OR
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NOT
• Inverts (reverses) a boolean value
• Truth table for Boolean NOT operator:
Digital gate diagram for NOT:
NOT
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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AND
• Truth table for Boolean AND operator:
Digital gate diagram for AND:
AND
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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OR
• Truth table for Boolean OR operator:
Digital gate diagram for OR:
OR
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Operator Precedence
• Examples showing the order of operations:
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Truth Tables (1 of 3)
• A Boolean function has one or more Boolean inputs,
and returns a single Boolean output.
• A truth table shows all the inputs and outputs of a
Boolean function
Example: X Y
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Truth Tables (2 of 3)
• Example: X Y
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Truth Tables (3 of 3)
• Example: (Y S) (X S)
S
X
mux
Z
Y
Two-input multiplexer
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Summary
• Assembly language helps you learn how software is
constructed at the lowest levels
• Assembly language has a one-to-one relationship
with machine language
• Each layer in a computer's architecture is an
abstraction of a machine
•layers can be hardware or software
• Boolean expressions are essential to the design of
computer hardware and software
Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007.
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