Assembly Programming

1. COMPUTER ORGANIZATION
& ASSEMBLY LANGUAGE
LECTURE # 4
BY MUHAMMAD JAFER
1

2. QUIZ
• Minutes (10)
• Total Marks (15)
• What are the basic components of a computer & task
perform by them ?
• Are these basic components dependent on each, if yes
then how and why ?
• Why do we need a memory model for a processor ?
• Name memory models for processor?
2

3. IMPORTANT CONCEPTS OF
8088/86
• Pipelining
• Registers
3

4. PIPELINING
• Making CPU Speed Faster
• Work Frequency
• Internal Architecture
• Work Frequency
• Technology Dependent
• Cost & Availability of Technology
• ICs Architecture
• Important decisions at architecture level
4

5. PIPELINING
• Internal Architecture
• Remember RISC & CISC
• Sequential execution of instructions
• Non-Pipelining
• 8085
• Pipelining
5

6. 6
nonpipelined
(e.g., 8085)
fetch 1 exec 1 fetch 2 exec 2
pipelined fetch 1 exec 1
(e.g., 8086)
fetch 2 exec 2
fetch 3 exec 3

7. PIPELINING
• Simplest Form
• Fetching & Execution
• Parallel
• Intel Implementation
• 8088/8086
• Splitting internal architecture into 2 units
• Bus Interface Unit
• Execution Unit
• BIU access Memory
• EU executes instructions
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8. BUS INTERFACE UNIT (BIU)
• In 8088/86 has a buffer &/or queue
• 8088 4 bytes long
• 8086 6 bytes long
• If Queue is full then ????? (Challenge 0.1)
• JUMP Command Problem
• Simples form 2 stages
• Can be complex
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9. EXECUTION UNIT (EU)
• Executes
• Slower than BIU
• Branch Penalty
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10. REGISTERS
• Why do we need registers
• 6 type of registers
• How to use them will be discussed in length during this
course when related instructions will come
• First Later of Indicates Its usage
• AX = Accumulator
• BX= Base Address
• CX= Counter in loops
• DX = Point to data in I/O operations
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11. 11
Category Bits Register names
16 AX, BX, CX, DX
General
8 AH, AL, BH, BL, CH, CL, DH, DL
Pointer 16 SP(stack pointer), BP(base pointer)
Index 16 SI(source index), DI(destination index)
Segment 16
CS(code segment), DS(data segment)
SS(stack segment), ES(extra segment)
Instruction 16 IP(instruction pointer)
Flag 16 FR(flag register)
Registers of 8086/286 by category

12. CHAPTER REVIEW
• The x86 PC Assembly Language, Design &
Interfacing by Muhammad Ali Mazidi, Janice
Gillispie Mazidi & Danny Causey
• Chapter # 1
• Inside The 8088/86
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