1. Assembly Language (CSW 353)
Introduction of Assembly Language
Assembly Language

2. Introduction of Assembly Language

3. Content Course Description Basic Concepts of Assembly Language
Welcome to Assembly Language
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

4. Course Description Prerequisites: Textbook References:
Structured Programming Language
Textbook References:
Assembly Language for Intel-Based Computers.
Assembly language for x86 processors
The Art of Assembly Language
Resources:
Assembly Language

5. Course Description Grading : Final Exam 65 Year work 10 Oral 10
Laboratory and Practice 15
Sum
Timing:
Lecture
Practice
Exam
Assembly Language

6. Content Course Description Basic Concepts of Assembly Language
Welcome to Assembly Language
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

7. Basic Concepts Welcome to Assembly Language Virtual Machine Concept
Some Good Questions to Ask
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

8. 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?
Assembly Language

9. 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 on 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.
Assembly Language

10. What is Assembly Language?
A Hierarchy of Languages
Assembly Language

11. 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.
Assembly Language

12. 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.
Assembly Language

13. The accumulator. General-purpose register.
What is Machine Language ML?
Each ML instruction contains an op code (operation code) and zero or more operands.
Examples:
Opcode Operand Meaning
increment the AX register
add 0005 to AX
The accumulator. General-purpose register.
Assembly Language

14. How is Assembly related to 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
Assembly Language

15. 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)
Assembly Language

16. How is Assembly related to High-Level Language?
Assembly Language

17. Basic Concepts Welcome to Assembly Language Virtual Machine Concept
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

18. 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.
Assembly Language

19. Translating languages
English: Display the sum of A times B plus C.
C++:
cout << (A * B + C);
General Data Register
Intel Machine Language: A F E
Assembly Language:
mov eax,A
mul B
add eax,C
call WriteInt
Assembly Language

20. Virtual machines
Abstractions for computers
Assembly Language

21. High-level language Level 5 Application-oriented languages
Programs are compiled into assembly language (Level 4)
cout << (A * B + C);
Assembly Language

22. 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 eax, A
mul B
add eax, C
call WriteInt
Assembly Language

23. Operating system Level 3 Provides services
Programs translated and run at the instruction set architecture level (Level 2)
Assembly Language

24. Instruction set architecture
Level 2
Also known as conventional machine language
Executed by Level 1 program (microarchitecture, Level 1) A F E
Assembly Language

25. Micro-architecture Level 1
Interprets conventional machine instructions (Level 2)
Executed by digital hardware (Level 0)
Assembly Language

26. Digital logic Level 0 CPU, constructed from digital logic gates
System bus
Memory
Assembly Language

27. Basic Concepts Welcome to Assembly Language Virtual Machine Concept
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

28. 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
Assembly Language

29. Binary representations
Electronic Implementation
Easy to store with bi-stable elements
Reliably transmitted on noisy and inaccurate wires
0.0V
0.5V
2.8V
3.3V 1
Assembly Language

30. 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:
A bit string could have different interpretations
Assembly Language

31. 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
Assembly Language

32. 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 = decimal 9:
(1  23) + (1  20) = 9
Assembly Language

33. Translating unsigned decimal to binary
Repeatedly divide the decimal integer by 2. Each remainder is a binary digit in the translated value:
37 =
Assembly Language

34. Binary addition
Starting with the LSB, add each pair of digits, include the carry if present.
Assembly Language

35. Integer storage sizes Standard sizes:
Practice: What is the largest unsigned integer that may be stored in 20 bits?
Assembly Language

36. Large measurements Kilobyte (KB), bytes Megabyte (MB), bytes
Gigabyte (GB), bytes
Terabyte (TB), bytes
Petabyte, bytes
Exabyte, bytes
Zettabyte, bytes
Yottabyte, bytes
Assembly Language

37. Hexadecimal integers
All values in memory are stored in binary. Because long binary numbers are hard to read, we use hexadecimal representation.
Assembly Language

38. Translating binary to hexadecimal
Each hexadecimal digit corresponds to 4 binary bits.
Example: Translate the binary integer to hexadecimal:
Assembly Language

39. 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
= (1  163) + (2  162) + (3  161) + (4  160)
= decimal 4,660.
Hex 3BA4
= (3  163) + (11 * 162) + (10  161) + (4  160)
= decimal 15,268.
Assembly Language

40. Converting decimal to hexadecimal
decimal 422 = 1A6 hexadecimal
Assembly Language

41. 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. 1 1 A B
78 6D 80 B5
Important skill: Programmers frequently add and subtract the addresses of variables and instructions.
Assembly Language

42. Hexadecimal subtraction
When a borrow is required from the digit to the left, add 10h to the current digit's value: -1
C6 75
A2 47
24 2E
Practice: The address of var1 is The address of the next variable after var1 is A. How many bytes are used by var1?
Assembly Language

43. Signed integers
The highest bit indicates the sign. 1 = negative, 0 = positive
If the highest digit of a hexadecimal integer is > 7, the value is negative. Examples: 8A, C5, A2, 9D
Assembly Language

44. Two's complement notation For Binary
Steps:
Complement (reverse) each bit
Add 1
Note that =
Assembly Language

45. 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
Assembly Language

46. Unsigned 2’s Complement Subtraction
Example: Find –
= 84 +(-67) = 17 –
The carry of 1 indicates that no correction of the result is required. 1
2’s comp
84-67

47. Unsigned 2’s Complement Subtraction
Example: Find –
= 67+ (-84) = -17 –
The carry of 0 indicates that a correction of the result is required.
Result = – ( )
2’s comp
2’s comp

48. Ranges of signed integers
The highest bit is reserved for the sign. This limits the range:
Assembly Language

49. Basic Concepts Welcome to Assembly Language Virtual Machine Concept
Some Good Questions to Ask
Assembly Language Applications
Virtual Machine Concept
Data Representation
Boolean Operations
Assembly Language

50. Boolean algebra Boolean expressions created from: NOT, AND, OR
Assembly Language

51. Digital gate diagram for NOT:
Inverts (reverses) a Boolean value
Truth table for Boolean NOT operator:
Digital gate diagram for NOT:
Assembly Language

52. Digital gate diagram for AND:
Truth if both are true
Truth table for Boolean AND operator:
Digital gate diagram for AND:
Assembly Language

53. Digital gate diagram for OR:
True if either is true
Truth table for Boolean OR operator:
Digital gate diagram for OR:
Assembly Language

54. Implementation of gates
Assembly Language

55. Operator Precedence Examples showing the order of operations:
Assembly Language

56. 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
Assembly Language

57. Truth Tables (2 of 2)
Example: X  Y
Assembly Language

58. 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
Assembly Language