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FY04: Introduction to the use of computers

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Acknowledgement

Jeremy Gow

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Last week’s lecture

Measuring digital data

Bits

Bytes

Kilobytes

Megabytes

...

SI and Binary units

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More Last week

Binary files

Hexadecimal

Text files

Character sets

Text encodings

ASCII, Unicode

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This week

What a computer really is

The Processor

Transistors

Processor architecture

Moore’s Law

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The story so far

Computers deal with binary data

Data storage have grown bigger over 50

years

Data is stored in files

Files are accessed through filesystems

The same file could be on several

filesystems

Text files = binary files + encoding

Binary data may be viewed as hexadecimal

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Storage and processing

So far we have looked at storing data

But computers also process data

Processing changes data

Computers are data processors

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Input and OutputI/O devices

Input

Keyboard

Mouse

Scanner

Network card

Storage

Output

Screen

Speakers

Printer

Network card

Storage

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Motherboard

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Describing Processors

A computer might be described as a

64-bit (Word)

2.3 GHz (Processor Speed)

3072 MB (Memory Capacity)

PC (Operating System/Platform)

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The Processor

Central Processing Unit (CPU)

AKA The Processor

Performs processing (computation)

Accesses resources (I/O devices)

Modern CPU built of millions of

transistors

Clock regulates processing (speed in

GHz)

e.g. Intel Core Duo: 151m transistors,

2.33 GHzjennifer george

‘Computer Speed & Capacity’

A computer’s speed is defined by:

The type of processor

Amount of RAM

....on the motherboard

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Who makes the (micro)processors?

Intel

Motorola

Advanced Micro Devices (AMD)

Cyrix

IBM

* Within the context of a PC, the terms

processors and microprocessors are

used interchangeably

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Microprocessors

Smaller than a postage stamp

Found in wristwatches, sewing

machines, CD players, elevators and

anything electronic

This is a computer on a chip

Chip refers to a self integrated circuit

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Known Microprocessors

1971: Intel 4004, 4044

First microprocessor

4-bit

1981 – 1984: Intel 8088, 8085

First 8-bit processor

Into the 90’s: Intel 286 (Intel 80286),

386, 386

1990’s-2000’s: Intel Pentium , Pentium

Pro, Pentium II & III, Celeron, Itanium

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The Processor

The nucleus or the brain of any

computer

The CPU(Processor) has two

fundamental sections:

Control Unit

Arithmetic and Logic Unit

These work together with the RAM

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Transistors

Electronic component

Applying voltage to one terminal affects

current flowing between other two

Acts as a switch

Can represent 0 or 1

(more with logic gates

next week)

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Integrated Circuits(Microchips, Silicon Chips)

Millions of electronic components, e.g.

Transistors

Components very close (millions per mm!)

Small area (mm!)

‘Printed’ onto silicon using light

Low power (less heat)

Low cost

High performance

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Computer Architecture

CPU on an integrated circuit

Control Unit co-ordinates activities

Clock regulates activity at a set

speed (GHz)

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Arithmetic-Logic Unit

Circuitary that performs operations on

data

Integer arithmetic operations (addition,

subtraction, multiplication, division)

Logic operations (next week)

Reads data from input registers

Control unit tells it which operation

Writes data to output registers

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Register Unit

Registers store data being worked on

by CPU

Example: adding two numbers

Move numbers from memory to input

registers

ALU writes answer to output register

New data moved from register to memory

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Moving data around

Bus moves data between CPU to

main memory

Takes time to transfer data

Cache stores recently used data in

CPU

Faster than retrieval from main memory

Avoids having to always use bus

Much smaller than main memory

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Coprocessors

Help main processor do special tasks

e.g. graphics, sound, encryption

Designed to be faster at this one task

Optional extra

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Parallel Processing Core 2 Duo

The concept of using multiple

processors in the same computer

system

One main processor examines the

problem and allocates portions to be

solved simultaneously

The individual pieces are then

reassembled in the main processor

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Putting more on the chip

Technology allows more & more circuitry

on chip

System on a chip: CPU + main

memory

Much faster bus transfer

Multi-core: more than one CPU on

chip

Can increase performance

Often have shared cache

Dual-core, quad-core etc.jennifer george

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Neural networks

Digital computers process structured

data sequentially

Neural networks process unstructured

information simultaneously

Digital computers are faster and

accurate in numeric computation

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Neural Networks

Neural networks are used where the

computer is required to function as a

human brain

Playing chess

Improving automobile engine efficiency

Enabling improved vision technology

Planning crop and rotation strategies

Forecasting financial market fluctuations

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Example: New 13” Macbook

Intel Core 2 Duo

Clock speed: 2.0 GHz or 2.4 GHz

Two CPUs on chip

3MB cache

1066MHz bus

2GB main memory

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Moore’s LawGordon Moore (1965)

The complexity for minimum component

costs has increased at a rate of roughly a

factor of two per year... Certainly over the

short term this rate can be expected to

continue, if not to increase. Over the longer

term, the rate of increase is a bit more

uncertain, although there is no reason to

believe it will not remain nearly constant for

at least 10 years. That means by 1975, the

number of components per integrated

circuit for minimum cost will be 65,000. I

believe that such a large circuit can be built

on a single wafer.

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Moore’s Law

The number of transistors that can be

cheaply placed on an integrated circuit

doubles every two years

Exponential growth in transistors-per-

chip

Related to increase in chip power

Roughly true since 1965

Result of many technological advances

Will approach physical limits at some

pointjennifer george

Moore’s LawIntel chips

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Summary

Processor (CPU) made of millions of

transistors

Integrated circuits allow small powerful

CPUs

Control Unit, ALU, Registers, Bus, Cache

Co- and multi-core processors

Moore’s law: transistors on chip double in 2

yrs

Reading: Brookshear 2.1, White 5 & 6

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