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

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

IMPORTANT CONCEPTS OF 8088/86 Pipelining Registers 3

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

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

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

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 7

BUS INTERFACE UNIT (BIU) In 8088/86 has a buffer &/or queue bytes long bytes long If Queue is full then ????? (Challenge 0.1) JUMP Command Problem Simples form 2 stages Can be complex 8

EXECUTION UNIT (EU) Executes Slower than BIU Branch Penalty 9

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 10

11 CategoryBitsRegister names 16AX, BX, CX, DX General 8AH, AL, BH, BL, CH, CL, DH, DL Pointer 16SP(stack pointer), BP(base pointer) Index16SI(source index), DI(destination index) Segment16 CS(code segment), DS(data segment) SS(stack segment), ES(extra segment) Instruction16IP(instruction pointer) Flag16FR(flag register) Registers of 8086/286 by category

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