computer organization

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Computer Organization

講師：陳育良

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第一章

計算機類型

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計算機類型個人電腦

桌上型筆記型

工作站企業級系統

伺服器 (low end):資料庫、Web Server大型主機 :商業資料處理超級電腦 (high end):氣象、模擬、彈道

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計算機功能單元 I/O

InputOutput

Memory CPU

ALUControl Unit

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計算機處理的資訊 Instruction(machine instructions, c.f.statem

ents) Program

Serial of instructions Source program compiler Object

Linkage Editor (reference to library) Image (executable) Loader Execution

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資料編碼 Bit -> byte -> word BCD(binary-coded decimal)

Mainframe ASCII(American Standard Code for Information

Interchage)7 bits

EBCDIC(Extended Binary-Coded Decimal Interchange Code)8 bits

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ASCII Table vs. EBCDIC Table

ASCII Table vs EBCDIC Table

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Functional Units

InputKeyboard, mouse, joystick

MemoryPrimary memory (DRAM、 SDRAM-Synchronous DRAM )

Address (byte)

Cache(SRAM-static random access memory )Secondary memory

Disk、 Tape、 CD-ROM

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CPU

ALU(arithmetic and logic unit) Registers (flip-flop)> Cache

high-speed storage area within the CPU CU (control unit)

Instruction Decoder and control logicCoordinator of other functional unitsSending control signals

Timng signal

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Instruction example

Add Loca, R0 Prefer

Load Local, R1Add R1, R0

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Registers

IR (Instruction register) PC (program counter) General-purpose register

AX, BX, DX, CX(8086) EAX,EBX,EDX,ECX(80x86)

MAR(memory address register) Is the register of a computer's control unit that contains the address of a regi

ster to fetch or store from or to the computer storage. The memory address register is half of a minimal interface between a microp

rogram and computer storage. The other half is a memory data register. MDR(memory data register)

Is the register of a computer's control unit that contains the contents of a register to fetch or store from or to the computer storage.

The memory data register is half of a minimal interface between a microprogram and computer storage. The other half is a memory address register

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Load Instruction(load Loca, R1)

MAR <- PC; PC <- PC + 4;

MDR <- MEM[MAR];

IR <- MDR;

MAR <- Ra + ADJ6(IR[5:0]);(compute operand’s effective address)

MDR <- MEM[MAR];(get operand)

Rdest <- MDR;(write register)

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Store Instruction(store Local, R1)

MAR <- PC; PC <- PC + 4;

MDR <- MEM[MAR];

IR <- MDR;

MAR <- Ra + ADJ6(IR[5:0]); (compute operand’s effective address)

MDR <- Rdest; (write MDR)

MEM[MAR] <- MDR; (write memory)

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Basic Computer Organization Revisited

Processor

General-PurposeRegisters

ControlLogic

Memory

I/O

MAR

MDR

PCALUs

Data

Program

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Interrupt

Preempt vs non-preempt Hardware interrupt

I/O interrupt Softwre interrupt

System calls Interrupt-service routine Context Switching

Keep status of CPU in stack

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BUS

Connect various devices Addressing lines Control lines Single bus

Low cost Two devices talk at any time

Multiple bus High cost Allow concurrency, high efficiency

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Buffer register

Equipped in devices for compensating the speed differences

MultiprogrammingCPU switches between running programs

when they are blocked in I/O

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System softwre I

Coordinate the activities within computer system

CompilerHigh level language

Do not need to know the underlay CPU

AssemblerAssembly language

Need to know the architecture of CPU

Text editor

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System softwre II

OS (Operating System)Distribute and manage resources for applicati

on programsMonolithic

Eg. Linux (but has been improved with loadable modules facility, also called kernel extension )

Microkernel Eg. Windows NT

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OS characteristics

Multiprogramming Multi-user vs. single user Multitasking vs. single task Time sharing Preempted

Windows NT, Linux Non-preempted

Windows 3.1

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Performance

Hardware cpu, memory hierarchy, pipelining, dynamic scheduling (fetch-issue out of order), Speculation (fetch-issue-execute)

Instruction set (CISC, RISC) Compiler (optimization, instructions unrolling) Processor time

Program + OS primitives

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Memory hierarchy

Cache principle L1 cache also called primary cache built into

the CPU L2 cache also called secondary cache,

usually resides on a separate chip from CPU Program characteristic

Temporal localitySpatial locality

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clock

Clock cycle (R) Period (P) R=1/P Hz(Hertz)

Cycles per second(每秒震動的次數 ) 500 MHz = 2 ns clock 1.25 GHz = 0.8 ns clock

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Basic performance equation

T = (N x S) / R T: program execution time N: Total number of Ins been executed

(not equal to ins of object code for looping or no visiting)

S: Instruction stages R: Clock rate

T -> down implies N,S down or R up Due to the variety of S, 900MHz maybe run slow than

700MHz

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Pipeline and superscalar

Pipeline Overlapping the execution of instructions Eg. Multiple workers in an assembly line of factory

Superscalar Issue and execute multiple instructions at the same ti

me with mutilple pipelines Concurrent execution (must be the same with the res

ults of sequential execution) Eg. Multiple assembly lines

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Instruction Set

CISCComplex Instruction Set ComputerEg. Intel CPU

RISCReduced Instruction Set ComputerSun SPARC, Power PC, Alpha

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Benchmark program

A baseline program for performance evaluation Real applications of various domains selected from

SPEC SPEC (Standard Performance Evaluation Corporatio

n) SPEC95 – reference machine is SUN SPARC statio

n 10/40 SPEC2000 -300MHz UltraSPARC-Iii SUN SPARC 1

0 SPEC evaluation= exe time of reference/exe time of

target

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Multiprocessor

Shared-memory multiprocessorMultiple CPU share common memory

Message-passing multicomputerDistributed computer architecutureEvery processor has local memory and comm

unicates with each other via LAN

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History(Stored program computer)by John Von Neumann First generation – 1945~1955

Vacuum tube millisecond

Second generation – 1955~1965 Transistor microsecond

Third generation – 1965-1975 IC Microprogramming, pipeline, parallel, cache, virtual memory

Fourth generation – 1975 ~ VLSI (very large scale integration) Nanosecond