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MT-210 Computer Fundamentals

Tutorial 8 ( part 1 )

Group 17

Tutor : Kenny YUEN

http://learn.ouhk.edu.hk/~t441063

Chapter 5 (Set Book)Computer Architecture

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It refers to the design & construction of a computer system

Computer Architecture

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Motherboard ( 底板 ) or main board Provide sockets for

chips (IC), slots for small circuit board, and circuitry that connecting these components

Provide expansion slots for connection with peripheral devices

such as EISA, PCI & APG slot

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Integrated Circuit (IC)

A thin slice of silicon crystal packed with microscopic circuits elements such as :

Wires, Transistors, Capacitors, and resistors

Chip Packages, including

DIP (dual in-line pin),

DIMM (dual in-line memory module)

PGA (pin-grid array)

SEC (single edge contact)

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Data Representation

An Analog device operates on continuously varying data

A Digital device works with discrete number,

digital computer represent numeric data using Binary Number system

Which has only 2 digits : [ 0 ] and [ 1 ]

"Character data" composed of letter, symbol, & numeral that will not be used in arithmetic operations

digital computers represent character data using codes and "Code Set".

ASCII := American Standard Code for Information Interchange

EBCDIC := Extended Binary-Coded Decimal Interchange Code

Most micro-computers use ASCII code to represent character data

Some mini, mainframe computers use EBCDIC code to represent character data

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Code Sets

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Data Transport [ Data bus ] is an electronic pathway or circuit that links the chips on the

motherboard for data to travel

The bus contains data line and address line

[data line ] : carry the signals that represent data

[address line ] : carry the signals that specify where the computer can find the data that it is supposed to process

Memory There are 2 major categories : Primary & Secondary

There are 4 major types of memory :

RAM : Random Access Memory

Virtual Memory : by the use of hard disk

CMOS : Complementary Metal Oxide Semiconductor

ROM : Read Only Memory

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RAM Temporarily holds {data, instructions } before/after it is processed until the computer is turn off.

Require power to hold. No power, then no data. A reusable computing resource as the contents can be changed

Virtual memory

Use space on hard disk, as an extension of RAM, to simulate RAM. Works slower than RAM because

RAM is electronic device Hard disk is mechanical device

Like RAM : no power, then data in virtual memory become in-accessible

ROM One or more chips containing instructions that help a computer prepare for processing tasks

Instructions in ROM are permanent The only ways to remove instructions is to remove that chips Holds Basic I/O system (BIOS) for PC bootstrap & tells the computer

how to access disk drives and other peripheral devices

CMOS More permanent then RAM but less permanent then ROM Stores hardware configuration, which can be changed Memory is powered by battery

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Central Processing Unit (CPU) The circuitry in a computer that execute instruction to process date

It takes instruction/data from RAM, process instructions then places the results back into RAM

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There are 2 main parts :

1/. Arithmetic Logic Unit (ALU), performs arithmetic operations such as addition & subtraction performs Logical operations such as comparing 2 numbers to check

if they are the same Use registers to hold data that is being processed The result of the ALU will be kept in accumulator,

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2/. Control Unit (CU), direct & control processing Use instruction pointer to keep track of instruction sequence Retrieve each instruction in sequence from RAM and place it in

instruction register

Interpret the instruction & may send signal to

data bus to :

fetch data from RAM

to the ALU to perform a process

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Instructions tells the computer to perform arithmetic, logical, or control operation

It has 2 parts

[op code ] = "operation code", a command word for an operation

Such as add, compare, or jump

[operands ] specify the data or address of the data for the operation

[ Instruction cycle] as, shown in margin, refers to the process that a computer executes a single instruction

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Processing Instructions

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Performance FactorsSystem Clock

generates pulses to establish the timing for all system operations,

sets speed/frequency for data transport & instruction execution

Thus, limits no of instructions to be completed in a fixed time slot

Word size

The no. of bits a CPU can manipulate at one time

Based on size of registers in the CPU & no. of data line in the bus

Cache

"RAM cache" or "cache memory", high speed memory that give the CPU more rapid access to data

when an instruction calls for data, the CPU 1st checks if it is in cache.

If yes, it takes it from cache. Otherwise, it fetch it from RAM which takes longer

Generally, more cache means faster processing

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RegisterCache

CMOS, ROMRAM

Primary Storage

Secondary Storage

Hard to increase

Easy to increase

Performance

Cost (bit / $ )

Decreasing

Increasing

Storage Size

Punch card, Tape

Floppy,

Zip disk,

CD,

DVD

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Instruction Set Complexity

CISC (Complex Instruction Set Computer)

Complex instructions are provided in this kind of machine, however

20% of the instructions of a CICS machine do about 80% of the work

RISC (Reduced Instruction Set Computer)

Has limited set of instructions that it can perform very quickly

In theory a RISC machine is faster than CISC machine for most tasks

Scientists believe that a balance or hybrid of CISC & RISC technologies produces the most efficient and flexible computer

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Pipelining

To speed up the processing

A processor can begin executing part of the next instruction(s) before the current instruction-1 completed, as shown below

Instruction-1 load process store

Instruction-2 load process store

Instruction-3 load process store

Time

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Parallel Processing these are Parallel Computers

Increase the amount of processing that a computer can accomplish in a specific amount of time

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Input & Output (IO) Refers to collecting data for the microprocessor to manipulate, and

transporting results to display, print and storage devices

[ Expansion Bus ] is a segment of the data bus that transports data between RAM and peripheral devices

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Expansion Slots & Cards Expansion Slot is a long, narrow socket on the motherboard, where

you can plug your expansion cards expansion card / controller card is a small circuit board that

provides a computer with the ability to control a storage, input, or output devices

Examples

Sound card

Modem card

LAN card

Capture card

AGP graphic card

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ISA Industry Standard Architecture An obsolete technology, used for some modem and other relatively slow

devices

PCI Peripheral Component Interconnect Offers faster transfer speeds and a 64-bit data bus Houses graphics card, sound card, video capture card, modem or

network interface card (LAN card)

AGP Accelerated Graphics Port Primarily used for graphics cards, Faster than a PCI slot Provides a high speed data pathway for 3D graphics

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Expansion port & cable

Expansion Port is any connector that passes data in & out of a computer or peripheral device

Ports are sometimes called "jacks" or "connector"

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