This document provides an introduction to assembly language programming. It begins by analyzing a simple program segment and showing the equivalent code in high-level language, assembly language, and machine language. It then discusses the Von Neumann architecture and how instructions are fetched, decoded, and executed sequentially from memory. The document compares a simple "Hello World" program written in assembly language and C. It discusses some advantages and disadvantages of using assembly language like compact code, speed, and flexibility versus ease of use, predefined functions, and portability of high-level languages. Finally, it provides a brief history of microprocessors and their increasing transistor counts, shrinking feature sizes, and faster clock speeds over time.

1. Assembly Language Programming
Chapter 1
Introduction

2. Analyze the program segment
beta = 5;
alpha = beta + 3;
mov byte ptr beta, 5
mov al, beta
add al, 3
mov alpha, al
C606000105
A00001
0403
A20002
High Level
Language
Assembly
Language
Machine
Language

3. Analyze the program segment
External Memory
03000 C6
03001 06
}mov byte ptr <address>, <value>
}
03002 00
03003 01
}0100 or beta
}
03004 05 }05
03005 A0}mov al, <address>
03006 00
03007 01
}0100 or beta
}
03008 04}add al, <value>
03009 03 }03
0300A A2}mov <address>, al
0300B 00
0300C 02
}0200 or alpha
}
mov byte ptr beta, 5
mov al, beta
add al, 3
mov alpha, al
C606000105
A00001
0403
A20002

4. Von Neumann architecture
External
Memory
MPUI/O
• has three basic hardware subsystems

5. control bus
data bus
address busaddress bus
data bus
control bus
Von Neumann architecture
External
Memory
MPUI/O
• the three basic hardware subsystems are
interconnected by three buses

6. control bus
data bus
address busaddress bus
data bus
control bus
Von Neumann architecture
External
Memory
MPUI/O
• program (actual code or instructions) and
data (i.e. variables) are stored in the main memory and
not in the MPU

7. control bus
data bus
address busaddress bus
data bus
control bus
Von Neumann architecture
External
Memory
MPUI/O
• instructions in the main memory are
fetched, decoded, and executed sequentially

8. MEM READ
03000
Von Neumann architecture
FETCH
MPU fetches the next instruction by specifying its
location in the address bus and specifying a
MEMORY READ control signal in the control bus
External Memory
03000 C6
03001 06
03002 00
03003 01
03004 05
03005 A0
03006 00
03007 01
03008 04
03009 03
0300A A2
0300B 00
0300C 02
control bus
data bus
address bus
MPU
Instruction
Fetched:

9. MEM READ
C6
03000
Von Neumann architecture
FETCH
External Memory will give data (which in this case
is actually part of an instruction) based on the
address specified by the MPU thru the address bus
External Memory
03000 C6
03001 06
03002 00
03003 01
03004 05
03005 A0
03006 00
03007 01
03008 04
03009 03
0300A A2
0300B 00
0300C 02
control bus
data bus
address bus
MPU
Instruction
Fetched:

10. Von Neumann architecture
DECODE
MPU will try to decode the instruction fetched. If
the instruction is already complete, it will proceed
with the execute phase, otherwise it will do
additional fetch(es) until instruction is complete
External Memory
03000 C6
03001 06
03002 00
03003 01
03004 05
03005 A0
03006 00
03007 01
03008 04
03009 03
0300A A2
0300B 00
0300C 02
control bus
data bus
address bus
MPU
Instruction
Fetched:
C6
this is not
yet
complete

11. Von Neumann architecture
DECODE
MPU will try to decode the instruction fetched. If
the instruction is already complete, it will proceed
with the execute phase, otherwise it will do
additional fetch(es) until instruction is complete
External Memory
03000 C6
03001 06
03002 00
03003 01
03004 05
03005 A0
03006 00
03007 01
03008 04
03009 03
0300A A2
0300B 00
0300C 02
control bus
data bus
address bus
MPU
Instruction
Fetched:
C606000105
mov byte
ptr [0100],
05

12. Von Neumann architecture
EXECUTE
the MPU will start to execute the instruction
previously decoded
External Memory
03000 C6
03001 06
03002 00
03003 01
03004 05
03005 A0
03006 00
03007 01
03008 04
03009 03
0300A A2
0300B 00
0300C 02
control bus
data bus
address bus
MPU
Instruction
Fetched:
C606000105
executing:
mov byte
ptr [0100],
05

13. Why Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language

14. Why Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
COMPACT CODE

15. Why Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
SPEED

16. Why Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
FLEXIBLE

17. Why NOT Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
EASY TO LEARN

18. Why NOT Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
PREDEFINED FUNCTIONS

19. Why NOT Assembly Language
TITLE Hello World Program
DOSSEG
.MODEL SMALL
.STACK 100h
.DATA
GREET DB "Hello World!", 10, 13, "$"
.CODE
BEGIN:MOV AX, @DATA
MOV DS, AX
MOV ES, AX
LEA DX, [GREET]
MOV AH, 09h
INT 21h
MOV AL, 00h
MOV AH, 4Ch
INT 21h
END BEGIN
#include <stdio.h>
void main()
{
printf(“Hello World!”);
}
High Level LanguageAssembly Language
PORTABILITY

20. History of Microprocessor
Name Date Transistors Microns
Clock
speed
Data
width MIPS
8080 1974 6,000 6 2 MHz 8 bits 0.64
16 bits
8-bit bus
80286 1982 134,000 1.5 6 MHz 16 bits 1
80386 1985 275,000 1.5 16 MHz 32 bits 5
80486 1989 1,200,000 1 25 MHz 32 bits 20
32 bits
64-bit bus
32 bits
64-bit bus
32 bits
64-bit bus
32 bits
64-bit bus
8088 1979 29,000 3
Pentium 1993 3,100,000 0.8
7,500,000 0.35
5 MHz 0.33
60 MHz 100
233
MHz ~300
Pentium III 1999 9,500,000 0.25
450
MHz ~510
Pentium II 1997
1.5 GHz ~1,700Pentium 4 2000 42,000,000 0.18