Transcript Document

Assembly Language for Intel-Based
Computers, 4th Edition
Kip R. Irvine
Chapter 1: Basic Concepts
Slides prepared by Kip R. Irvine
Revision date: 07/21/2002
• Chapter corrections (Web) Assembly language sources (Web)
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Chapter Overview
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Welcome to Assembly Language
Virtual Machine Concept
Data Representation
Boolean Operations
Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003.
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Welcome to Assembly Language
• Some Good Questions to Ask
• Assembly Language Applications
Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003.
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Some Good Questions to Ask
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•
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Why am I taking this course (reading this book)?
What background should I have?
What is an assembler?
What hardware/software do I need?
What types of programs will I create?
What do I get with this book?
What will I learn?
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Welcome to Assembly Language (cont)
• How does assembly language (AL) relate to machine
language?
• How do C++ and Java relate to AL?
• Is AL portable?
• Why learn AL?
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Assembly Language Applications
• Some representative types of applications:
• Business application for single platform ( application for
only one computer).
• Hardware device driver(programs used to control the
input/output devices).
• Business application for multiple platforms( network
base application)
• Embedded systems & computer games(programs
design to control a specific machines or devices).
(see next panel)
* HL = high-level
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Comparing ASM to High-Level Languages
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Examples
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Some Keywords
• Assembly Language (ASM) Uses instruction mnemonics
that have a one-to-one correspondence with machine
language.
• Machine Language (ML) Numeric instructions(binary
numbers) and operands that can be stored in memory and
directly executed by the computer processor(CPU).
•
What is an assembler? An assembler is a program that
converts source code program from assembly language
into machine language (such as listing files generated by
an assembler)
• A linker is program that combines individual files created
by an assembler into a single executable program(the
assembler produce object codes programs need to link
with other object codes to be an executable program)
• A debugger is a program that provides a way for
programmer to trace the execution of a program and
examine the content of memory(execute the program step
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What hardware/software do I need?
For hardware you need computer with Intel386,Intel486
or one of the Pentium processors and all of these
belong to IA-32 family (Intel Architecture 32 bit
address family)(the address bus size is the number of
wires used to transmit the address between cpu and
the RAM)
For Software you need
• Editor : text editor to write an assembly language
source file
• Assembler : MASM version 6.15(Microsoft Assembler)
• Linker : to produce executable file
• Debugger : using Microsoft Visual Studio
(msdev.exe) debugger which is a part of Microsoft
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Visual C++
Virtual Machine Concept
• Virtual Machines
• Specific Machine Levels
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Virtual Machines
• Tanenbaum: Virtual machine concept
• Programming Language analogy:
• 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:
• (1) Interpretetation – L0 program interprets and executes L1
instructions one by one(the interpreter execute the higher
machine instructions in the lower machine one instruction at
a time)
• (2)Translation – L1 program is completely translated into an
L0 program, which then runs on the computer hardware
(compiler translate whole the higher language program into
lower language program)
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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
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High-Level Language
• Level 5
• Its called high level programming language
because it use the human language
statements (Ex: if, for, and while
statements).
• Application-oriented languages( develop
application programs that are use to satisfy
the user requirements).
• Programs compile into assembly language
(Level 4)
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Assembly Language
• Level 4
• Instruction mnemonics that have a one-toone correspondence to machine language
• Calls functions written at the operating
system level (Level 3)
• Programs are translated into machine
language using the assembler (Level 2)
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Operating System
• Level 3
• Provides services to Level 4 programs.
• The operating system provide a services as
a system calls that helps the application
programs to use the computer hardware
easily, smoothly, and efficiently.
• Programs translated and run at the
instruction set architecture level (Level 2)
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Instruction Set Architecture
• Level 2
• Also known as conventional machine
language
• The machine language is a zero/one
language (Binary numbers) which can be
executed by the computer hardware
directly.
• Executed by Level 1 program
(microarchitecture, Level 1)
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Microarchitecture
• Level 1
• Its called micro architecture level because
in PC the CPU called microprocessor and it
represent the brain of the computer.
• In that level the computer hardware are
classify conceptually into four components
(CPU, Main memory, Input/output devices
and Bus system)
• Interprets conventional machine
instructions (Level 2)
• Executed by digital hardware (Level 0)
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Digital Logic
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Level 0
CPU, constructed from digital logic gates
System bus
Memory
The hardware components are design and
implemented using electronically elements
like the transistors which works by the
electric power to execute and represent the
machine language programs.
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Data Representation
• Binary Numbers
• Translating between binary and decimal
• Binary Addition
• Integer Storage Sizes
• Hexadecimal Integers
• Translating between decimal and hexadecimal
• Hexadecimal subtraction
• Signed Integers
• Binary subtraction
• Character Storage
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Binary Numbers
• The computer system logic circuits understand only two voltages
levels on or off (true or false, 0 or 1).
• We use the binary numbering system to be match with the
computer language.
• Bit means Binary Digit
• Digits are 1 and 0
• 1 = true
• 0 = false
• MSB – most significant bit
• LSB – least significant bit
• Bit numbering:
Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003.
MSB
LSB
1011001010011100
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0
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Binary Numbers
• 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
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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
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Translating Unsigned Decimal to Binary
• The method called division and remainder.
• Repeatedly divide the decimal integer by 2. Each
remainder is a binary digit in the translated value:
(37)10 = (100101)2
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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
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Integer Storage Sizes
• The computer system is a deterministic machine
which means that it can deal and process specific
number of bits at a time as it design.
• These standard sizes called standard storage sizes.
• Number of combinations = 2 number of bits
• The range is from 0 to 2 number of bits -1
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Integer Storage Sizes
byte
Standard sizes:
word
doubleword
quadword
8
16
32
64
Practice: What is the largest unsigned integer that may be stored in 20
bits?
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Hexadecimal Integers
All values in memory are stored in binary. Because long
binary numbers are hard to read, we use hexadecimal
representation.
We use the hex numbering system because it has
direct relationship to the binary (each four bits represent
by one hex digit)
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Examples
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Translating Binary to Hexadecimal
• Each hexadecimal digit corresponds to 4 binary bits.
• Example: Translate the binary integer
000101101010011110010100 to hexadecimal:
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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.
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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, 2003.
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Converting Decimal to Hexadecimal
decimal 422 = 1A6 hexadecimal
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Examples
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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.
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Hexadecimal Subtraction
• When a borrow is required from the digit to the left, add
10h to the current digit's value:
10h + 5 = 15h
-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?
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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 hexadecmal integer is > 7, the value is
negative. Examples: 8A, C5, A2, 9D
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Forming the Two's Complement
• Negative numbers are stored in two's complement notation
• Additive Inverse of any binary integer
• Steps:
• Complement (reverse) each bit
• Add 1
Note that 00000001 + 11111111 = 00000000
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Binary Subtraction
• When subtracting A – B, convert B to its two's
complement
• Add A to (–B)
1100
– 0011
1100
1101
1001
Practice: Subtract 0101 from 1001.
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Learn How To Do the Following:
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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
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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?
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Examples
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Character Storage
• To store text data inside the computer we
need to represent each symbol by a binary
code using a specific code type.
• Character sets
• Standard ASCII (0 – 127) seven bits.
American Standard Code for Information
Interchange.
• Extended ASCII (0 – 255) Eight bits
• ANSI (0 – 255) eight bits
• Unicode (0 – 65,535) 16 bits
• Null-terminated String( is a symbol with code
equal 00000000 to indicate the string end).
• Array of characters followed by a null byte
• Using the ASCII table
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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"
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Boolean Operations
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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
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AND
• Truth table for Boolean AND operator:
Digital gate diagram for AND:
AND
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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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• Number of rows at the truth table depend on the
number of the variables on the Boolean expression.
• Number of rows = 2 Number of variables
•
•
•
•
Example: With one variable we needs two rows.
With Two variables we need four rows.
With three variables we need 8 rows.
With four variables we need 16 rows.
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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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54 68 65 20 45 6E 64
What do these numbers represent?
Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003.
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Examples
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