Week 1 - Computer Systems & Networks Notes

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Definitions

A computer

1. Accepts input in the form of instructions and data

2. Process the data according to a set of instructions

(program)

3. Produces output in the form of information or actions

What is a computer System?

-

A combination of hardware, software and network

components that work together to perform data processing, transfer and storage

tasks.

-

Includes one or more connected processing units,

memory storage and Input/Output (IO) located centrally or remotely via a

network

Moore’s Law: in 1965, Gordon Moore predicted that the number

of transistors integrated on a chip would double every 18 months – he was wrong

it was every two years

Amdhal’s law – the overall performance of a system is a

result of the interaction of all its components. As one function speeds up,

another will become the bottleneck

The performance improvement of using some fastermode of

execution is limited by the fraction of the time the faster mode can be used

Nanotechnology

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Nanotechnology refers to any new technology that

is put together atom by atom or molecule by molecule and is less than 100

nanometres in size

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A nanometre is a billionth of a metre, by

comparison the smallest transistors on a IC today are about 200 nanometres in

size

-

Nanotechnology includes quantum computers as

well as micromachines

Computer Types

PDAs/Mobile Handheld devices -

$800

Embedded/network computers

Have limited storage and only run

single application

Micro Computers (eg PC’s) - $1500

Single user

Servers/minicomputers - $10,000

Multiuser systems typically for

serving applications

Mainframe - $500,000

Large centralised enterprise-wide

computer

Typically replaced with “server

farms”

Supercomputer - $2,000,000

High-performance special purpose

computers

Computer systems abstractions

Hardware Model - Software Model

The Internet – Distributed Network

Programs

LANS (local area networks) – Scripts & VM byte

codes – PHP, Java etc.

Computer Systems (PCs) – Virtual

machines/applications – app.exe, java.exe

Circuit Boards (e.g. motherboard,

video card) – Operating Systems - DOS, Unix, Windows

Components (CPU, RAM) – Processor

instructions – MOV AX,5, JMP, sub

Logic Gates – Binary Logic –

0010101

Mechanical Computers – 1840

-

Charles Babbage’s difference engine

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For calculating tables (e.g. Sine & Polynomial)

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Used gears and wheels and other mechanical

movements

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You had to turn a crank handle to make it work

Electromechanical Computers – 1940

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First built from relays and were slow and noisy

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ENIAC: was the first fully electrical computer

using vacuum tubes

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Designed for calculating bombing trajectories

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It was huge

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Less powerful than a pocket computer

Electronic Computers – 1950s

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First electronic computers built from 20,000

vacuum tubes instead of relays

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Vacuum tubes generated a lot of heat and used as

much power as a small city

-

With the invention of the transistor in the

early 1950’s computers were finally set to take off

First Intergrated CPU – 1971

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Intel 4004 processor

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4 bit data + 8 bit instruction

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Contained 2300 transistors

-

Addressable memory was 640 bytes

-

Used to build the world’s first pocket

calculator

Drastic Performance Increases

Processor

-

logic capacity: about 30% ~ 35% per year

-

clock rate: about 20% ~ 30% per year

Memory

-

DRAM capacity: about 60% per year (4x every 3

years)

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Memory speed: about 10% per year

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Cost per bit: improves about 25% per year

- DRAM chip capacity increases x4 every two years

Disk Storage

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Capacity: about 60% ~ 100% per year

-

Speed: about 10% per year

Network Bandwidth

-

1Mbps -

10 Mbps - 100Mbps - 1 Gbps

Moore’s Law in Pictures

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1951 First transistor that can be made in

quantity

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1961 First logic Integrated Circuit (dual

flip-flop with 4 transistors

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1963 Integrated Circuit with 4 flip-flops

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1967 Integrated Circuit with 150 logic gates

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The first Integrated Circuit 1961(4 transistors)

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IBM PowerPC 750 in 1999 (10M transistors)

Disk Storage

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1920-60s punch cards used for storage

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1950 finally, tape drives started to replace

punch cards. Followed some years later, by magnetic drums.

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1956, The first hard drive It required 50

24-inch disks to store 5 MB of data and cost roughly $35,000 a year to lease.

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1973 - IBM introduces the Winchester hard disk

unit.

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The first PCs used paper tape and Data (audio)

cassette recorder, which was very slow.

-

1983 First 5.25-inch hard disk drives with 5MB

(10 MB was considered too large for personal computers).

-

1987 First 3 ½ inch drive appears with 300MB

capacity

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1992 First 2 ½ inch drive appear with 100MB

capacity

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2000 First 1 inch drive appear with 350MB

capacity

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2004 First 0.88 inch drive appears with 4GB

capacity

Quantum vs Optical computers

Quantum

- Gates get so small they are made of only a few atoms

- Extremely fast and small

- Based on quantum mechanics laws not classical physics

- Does not use binary but quantum bits (qubits)

- Qubits have 3 states: 0 or 1 or both at the same time with a value to represent the probability for each state

Optical

- In theory much faster than electronics

- Originally for special purpose applications

- For general purpose computing – currently bigger and slower\

- Could eliminate interconnection and simplify fabrication

Molecular

- Based on DNA molecule

- Can be “open” or “closed”

definitions

Nanotechnology + Quantum & Optical Computers

Computer types + system abstractions

brief computer history + Performance increases

Moore's Law + Disk Storage