Transcript ch. 1
Content
Course Description
Basic Concepts of Assembly Language
Welcome to Assembly Language
Virtual Machine Concept
Data Representation
Boolean Operations
Course Description
The general aims of course :
The computer architecture
Low-level programming in assembly language
Intended Learning Outcomes of Course:
Describing main components of computer system and their functionality.
Understanding the register level.
Understanding the basic assembly programming.
Describing techniques for the performance and reliability of processors,
memory, I/O devices.
Explaining the use of parallelism, caching, error-detection and correction.
Understanding of the aspects of computer arithmetic.
Explaining the need for resource management in a computer system.
Illustrating the multiprogramming and identifying synchronization.
Course Description
Reasons for using assembly
• Understanding how CPUs and compilers work.
• Developing compilers, debuggers and other development
tools.
• Hardware drivers and system code.
• Embedded systems.
• Developing libraries.
• Accessing instructions that are not available through highlevel languages.
• Optimizing for speed or space.
Course Description
Prerequisites:
Structured Programming Language
Textbook References:
Assembly Language for Intel-Based Computers.
Assembly language for x86 processors
The Art of Assembly Language
Resources:
http://web.sau.edu/LillisKevinM/csci240/masmdocs/
http://kipirvine.com/asm/4th/asmsources/
http://forum.codecall.net/topic/62064-assembly-language-resources/
Course Description
Grading :
• Final Exam
• Year work
• Oral
• Laboratory and Practice
• Sum
65
10
10
15
100
Timing:
• Lecture
• Practice
• Exam
3
2
3
Content
Course Description
Basic Concepts of Assembly Language
Welcome to Assembly Language
Virtual Machine Concept
Data Representation
Boolean Operations
Basic Concepts
Welcome to Assembly Language
Some Good Questions to Ask
Virtual Machine Concept
Data Representation
Boolean Operations
Welcome to Assembly Language
Some Good Questions to Ask
What is Assembly Language?
Why Learn Assembly Language?
What is Machine Language?
How is Assembly related to Machine Language?
What is an Assembler?
How is Assembly related to High-Level Language?
Is Assembly Language portable?
What is Assembly Language?
A low-level processor-specific programming language
design to match the processor’s machine instruction set.
Each assembly language instruction matches exactly one
machine language instruction.
We will focus to Intel based Assembly Instructions.
It covers many different versions of CPUs that followed, from Intel; the 80188,
80186, 80286, 80386, 80486, Pentium, Pentium Pro, and so on.
It describes the basics of 32-bit assembly language programming.
What is Assembly Language?
A Hierarchy of Languages
Why Learn Assembly Language?
To learn how high-level language code gets translated into
machine language.
To learn the computer’s hardware by direct access to
memory, video controller, sound card, keyboard…
To speed up applications by direct access to hardware.
What is Machine Language ML?
Machine languages are lowest-level programming language
and are the only languages understood by computers
without translation.
While easily understood by computers, machine languages
are almost impossible for humans because they consist
entirely of binary digits.
Every CPU has its own specific machine language.
What is Machine Language ML?
Each ML instruction contains an op code (operation code)
and zero or more operands.
Examples:
Opcode
Operand
Meaning
------------------------------------------40
05
0005
increment the AX register
add 0005 to AX
How is Assembly related to Machine Language?
Machine language
Native to a processor: executed directly by hardware
Instructions consist of binary code: 1s and 0s
Assembly language
Slightly higher-level language
Readability of instructions is better than machine language
One-to-one correspondence with machine language
instructions
Assemblers translate assembly to machine code
Compilers translate high-level programs to machine code
Either directly, or
Indirectly via an assembler
What is an Assembler?
An assembler is a type of computer program that
interprets software programs written in assembly
language into machine language, code and instructions
that can be executed by a computer.
For Example, MASM (Macro Assembler from Microsoft)
How is Assembly related to High-Level Language?
Basic Concepts
Welcome to Assembly Language
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Virtual Machine Concept
A virtual machine (VM) is a software program or
operating system that
• exhibits the behavior of a separate computer.
• is capable of performing tasks such as running
applications and programs in a separate computer.
VM virtual machine is a layer of abstraction that gives a
program one simplified interface for interacting with a
variety of physical computers and their operating
systems.
Translating languages
English: Display the sum of A times B plus C.
C++:
cout << (A * B + C);
Assembly Language:
mov eax,A
mul B
add eax,C
call WriteInt
Intel Machine Language:
A1
F7
03
E8
00000000
25 00000004
05 00000008
00500000
Virtual machines
Abstractions for computers
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
High-level language
Level 5
• Application-oriented languages
• Programs are compiled into assembly language
(Level 4)
cout << (A * B + C);
Assembly language
Level 4
• Instruction mnemonics that have a one-to-one
correspondence to machine language
• Calls functions written at the operating system
level (Level 3)
• Programs are translated into machine language
(Level 2)
mov
mul
add
call
eax, A
B
eax, C
WriteInt
Operating system
Level 3
• Provides services
• Programs translated and run at the instruction
set architecture level (Level 2)
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
Instruction set architecture
Level 2
• Also known as conventional machine language
• Executed by Level 1 program (microarchitecture,
Level 1)
A1
F7
03
E8
00000000
25 00000004
05 00000008
00500000
Micro-architecture
Level 1
• Interprets conventional machine instructions
(Level 2)
• Executed by digital hardware (Level 0)
Digital logic
Level 0
• CPU, constructed from digital logic gates
• System bus
• Memory
Basic Concepts
Welcome to Assembly Language
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Data representation
• Computer is a construction of digital circuits with two
states: on and off
• You need to have the ability to translate between
different representations to examine the content
• Common number systems: binary, octal, decimal and
hexadecimal
Binary representations
• Electronic Implementation
– Easy to store with bi-stable elements
– Reliably transmitted on noisy and inaccurate wires
0
3.3V
2.8V
0.5V
0.0V
1
0
Binary numbers
• Digits are 1 and 0
(a binary digit is called a bit)
1 = true
0 = false
• MSB –most significant bit
• LSB –least significant bit
• Bit numbering:
MSB
LSB
1011001010011100
15
• A bit string could have different interpretations
0
Unsigned binary integers
• Each digit (bit) is either 1 or 0
• Each bit represents a power of 2:
Every binary
number is a
sum of powers
of 2
1
1
1
1
1
1
1
1
27
26
25
24
23
22
21
20
Translating binary to decimal
•Weighted positional notation shows how to calculate
the decimal value (dec) 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
Translating unsigned decimal to binary
• Repeatedly divide the decimal integer by 2. Each remainder is
a binary digit in the translated value:
37 = 100101
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
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?
Large measurements
• Kilobyte (KB),
bytes
• Megabyte (MB),
bytes
• Gigabyte (GB),
bytes
• Terabyte (TB),
bytes
• Petabyte,
bytes
• Exabyte,
bytes
• Zettabyte,
bytes
• Yottabyte,
bytes
Hexadecimal integers
• All values in memory are stored in binary. Because
long binary numbers are hard to read, we use
hexadecimal representation.
Translating binary to hexadecimal
• Each hexadecimal digit corresponds to 4 binary bits.
• Example: Translate the binary integer
000101101010011110010100 to hexadecimal:
Converting hexadecimal to decimal
• Multiply each digit by its corresponding power of 16:
dec = (D3 163) + (D2 162) + (D1 161) + (D0 160)
Examples:
• 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.
Converting decimal to hexadecimal
decimal 422 = 1A6 hexadecimal
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
Important skill: Programmers frequently add and subtract the
addresses of variables and instructions.
Hexadecimal subtraction
• When a borrow is required from the digit to the left,
add 10h to the current digit's value:
-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?
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
Two's complement notation For Binary
Steps:
– Complement (reverse) each bit
– Add 1
Note that 00000001 + 11111111 = 00000000
Hexadecimal Two’s Complement
Steps:
– Complement (reverse) each digit (to reverse the bits
of a hexadecimal digit is to subtract the digit from 15.)
– Add 1
Binary subtraction
• When subtracting A – B, convert B to its two's
complement
• Add A to (–B)
01010
01010
– 01011
10101
11111
Ranges of signed integers
•
The highest bit is reserved for the sign. This limits
the range:
Basic Concepts
Welcome to Assembly Language
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Boolean algebra
• Boolean expressions created from:
– NOT, AND, OR
NOT
• Inverts (reverses) a Boolean value
• Truth table for Boolean NOT operator:
Digital gate diagram for NOT:
NOT
AND
• Truth if both are true
• Truth table for Boolean AND operator:
Digital gate diagram for AND:
AND
OR
• True if either is true
• Truth table for Boolean OR operator:
Digital gate diagram for OR:
OR
Implementation of gates
Operator Precedence
•Examples showing the order of operations:
Truth Tables (1 of 2)
• 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
Truth Tables (2 of 2)
• Example: X Y
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