© ncc education limited v1.0 introduction to computing unit 1: introduction to computer systems

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© NCC Education LimitedV1.0

Introduction to Computing

Unit 1: Introduction to Computer Systems

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Introduction to Computer Systems Unit 1 - 1.2

Summary of the Lecture

• Some definitions• The parts of a computer system• Examples of computer systems• Data and information• Developments past and present

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Introduction to Computer Systems Unit 1 - 1.3

A Computer

• Electronic machine• Processes data• Programmable (follows stored

instructions)• Usually multi-purpose (but not all are)

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Introduction to Computer Systems Unit 1 - 1.4

Hardware

Physical devices you can see and touch

Examples:• Screens• Keyboards• Printers

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Introduction to Computer Systems Unit 1 - 1.5

Hardware

• Physical components- such as memory, network cards, wires

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Introduction to Computer Systems Unit 1 - 1.6

Software

Software = Computer Instructions• A set of instructions that the computer

carries out• Usually these are carried out one after

another• The software is stored in primary

memory when it is run

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Introduction to Computer Systems Unit 1 - 1.7

Data

• We use computers to process data.• Data = facts• Data comes in many sorts

- text- numbers- images- music

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Introduction to Computer Systems Unit 1 - 1.8

Data

To a computer, all data is the same

00010100101010111101010101010

- a collection of bits

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Introduction to Computer Systems Unit 1 - 1.9

Bits• A bit is the smallest unit of data

• It can be only one of two things:- 0 or 1

• Bits can easily be represented in a computer by switches or transistors

• They are either on or off• A collection of bits can represent any data

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Introduction to Computer Systems Unit 1 - 1.10

A system

• A collection of parts• Acting together• For some defined purpose

• A system has a boundary

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Introduction to Computer Systems Unit 1 - 1.11

A System

System OutputInput

processing

sub

systemsystem

boundary

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Introduction to Computer Systems Unit 1 - 1.12

Examples of Systems

• Digestive system• Banking system• Transport system

What are the parts making up these systems?

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Introduction to Computer Systems Unit 1 - 1.13

Computer Systems

• The hardware, software and data needed to solve a real-world problem

• The components depend on the problem being solved

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Introduction to Computer Systems Unit 1 - 1.14

Hardware

Hardware is any part of a computer system that you can see and touch.

keyboard RAM router

processor printer sensor

cables network card loudspeaker

ports hub motor

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Introduction to Computer Systems Unit 1 - 1.15

Hardware

Hardware is often classified into:

• Input devices

• Output devices

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Introduction to Computer Systems Unit 1 - 1.16

Hardware

But there are other ways of looking at it:

• Communications

• Storage

• Processing

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Introduction to Computer Systems Unit 1 - 1.17

Hardware

Processor Output device

Inputdevice

Inputdevice

Inputdevice

Output device

Output device

InputPeripherals

OutputPeripherals

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Introduction to Computer Systems Unit 1 - 1.18

Input Devices

• Computers can only work with digital data – 0 or 1

• Much of the world is analogue

• Most input devices change analogue data into digital data

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Introduction to Computer Systems Unit 1 - 1.19

Analogue and Digital Data

Analogue datacontinuously

variable

Digital dataonly two states

0 or 1

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Introduction to Computer Systems Unit 1 - 1.20

Input Devices

Common PC input devices:• keyboard• mouse• webcam• microphone• scanner

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Introduction to Computer Systems Unit 1 - 1.21

Input Devices

More examples:• supermarket checkout scanner• temperature sensor• pressure pad in a burglar alarm system• pressure sensor in an aircraft altimeter• OMR reader• RFID reader

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Introduction to Computer Systems Unit 1 - 1.22

Output Devices

These are often needed to convert digital data to analogue information.

They are aimed at human senses or other devices.

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Introduction to Computer Systems Unit 1 - 1.23

Output Devices

Common PC output devicesprinter (ink jet / laser)

screen (some CRT but most now are TFT liquid crystal devices)

these use dots or pixels to produce imagesthe more dots, the better the resolution

speakers

visible

audible

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Introduction to Computer Systems Unit 1 - 1.24

Output Devices

More examples:• plotters• motors• heaters• lights• actuators• switches

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Introduction to Computer Systems Unit 1 - 1.25

Storage Devices

• Data usually needs to be kept for the future

• RAM is volatile and limited• Secondary storage for permanence• Secondary storage is getting faster

and cheaper all the time

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Introduction to Computer Systems Unit 1 - 1.26

Secondary Storage

Magnetic is still important• hard disks, even tapes

Optical• cd• dvd• blu ray

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Introduction to Computer Systems Unit 1 - 1.27

Secondary Storage

Solid state• likely to become more important

- sub notebook PCs- flash memory- camera cards- SIM cards- USB memory sticks

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Introduction to Computer Systems Unit 1 - 1.28

Software

• The instructions that a computer follows

• Produced as a program• Stored on secondary storage• Copied into RAM for running

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Introduction to Computer Systems Unit 1 - 1.29

Software

System software•controls the hardware•makes the hardware

usable- by humans- and other software

Application software

•does the jobs that we want

•solves real-world problems

Can be divided into two main groups:

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Introduction to Computer Systems Unit 1 - 1.30

System Software

• Operating systems• Translation software• Database management systems• Utilities

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Introduction to Computer Systems Unit 1 - 1.31

System Software

Operating systems• Examples: Windows, Unix, Linux, Mac OS• Hide the complexities of the machine• Manage memory• Provide a user interface• Manage peripherals• Manage files

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Introduction to Computer Systems Unit 1 - 1.32

System Software

Types:• Single job stream• Multiprogramming• Real-time• Network

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Introduction to Computer Systems Unit 1 - 1.33

System Software

Single job stream• Early computers processed jobs on

after another• The operating system had to load and

run each job• The CPU was idle when awaiting input

or output

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Introduction to Computer Systems Unit 1 - 1.34

System Software

Multiprogramming• More than one program in RAM at the

same time• Each process is allocated a time slice• CPU switches its attention between

programs• The CPU is used more of the time

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Introduction to Computer Systems Unit 1 - 1.35

System Software

Multiprogramming

notice that the processor is active all the time

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Introduction to Computer Systems Unit 1 - 1.36

System Software

Real-time• Output is given immediately after

input- Needed for bookings- Games- Control- Safety-critical systems

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Introduction to Computer Systems Unit 1 - 1.37

Virtual Memory

• A program can be divided into segments

• Segment loaded into RAM by OS when needed

• Unused segments stay on secondary storage

• Reduces amount of RAM required• Allows bigger programs to be written

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Introduction to Computer Systems Unit 1 - 1.38

Network Operating Systems Allow connected computers to:

• Communicate• Share resources• Divide work

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Introduction to Computer Systems Unit 1 - 1.39

Network Operating Systems

• Allow logins• Identify users• Provide security• Log activity

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Introduction to Computer Systems Unit 1 - 1.40

Translation Software

The CPU only executes machine code:

• Most programs are written in a human readable form (source code)

• The source code has to be translated into machine code

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Introduction to Computer Systems Unit 1 - 1.41

Translation Software

Assembler• works on low level source code – produces a

runnable program file

Compiler• works on high level source code – produces a

runnable program file

Interpreter• works on high level code and executes it as

it goes – no new file produced

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Introduction to Computer Systems Unit 1 - 1.42

Database Management Systems

• Provide a way of separating data form applications

• Allow applications to be created that do not conflict with each other

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Introduction to Computer Systems Unit 1 - 1.43

Utilities

• Operating systems provide a host of utilities

• These are small programs designed to do a limited range of tasks

• E.g. formatter, defragmenter, text editor, compression software

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Introduction to Computer Systems Unit 1 - 1.44

Different Types of Computer Systems

•Personal Computer•Desktop•Laptop•PDA•Notebook•Sub-notebook

•Workstation•Server•Mainframe•Minicomputer•Supercomputer•Embedded Devices

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Introduction to Computer Systems Unit 1 - 1.45

The Most Common Computer in the World?

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Introduction to Computer Systems Unit 1 - 1.46

Data and Information

Data is just facts / symbols:• Computers work with data• They manipulate groups of binary digits• They do exactly what we tell them

Information is facts in context:• We need information• Computers output information

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Introduction to Computer Systems Unit 1 - 1.47

Data and Information

This is data:• 231189 (the numbers could mean

anything)

This is information:• 23/11/89 (now it looks like a date)

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Introduction to Computer Systems Unit 1 - 1.48

How Computers Developed

The Babbage Difference Engine (designs started 1822)

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Introduction to Computer Systems Unit 1 - 1.49

ColossusThe First Electronic Computer

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Introduction to Computer Systems Unit 1 - 1.50

The First Generation

Colossus • The first electronic, programmable,

digital computing device• Used 2400 electronic valves• Designed by Tommy Flowers• Used to decode wartime code

messages

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Introduction to Computer Systems Unit 1 - 1.51

Second generation

Transistors Replace Valves:•Faster•Use less energy•More reliable•Cheaper•Smaller

http://upload.wikimedia.org/wikipedia/commons/e/e2/Transistor-die-KSY34.jpg

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Introduction to Computer Systems Unit 1 - 1.52

Third Generation

Integrated circuits• More size and cost reductions• Faster

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Introduction to Computer Systems Unit 1 - 1.53

Fourth Generation

Millions of transistors packed onto a chip• More size reduction• More speed gains

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Introduction to Computer Systems Unit 1 - 1.54

Giving Instructions

patched wires

paper tape

punched cards

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Introduction to Computer Systems Unit 1 - 1.55

Giving Instructions

Console and tape storage - 1970

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Introduction to Computer Systems Unit 1 - 1.56

Giving Instructions

Instructions in hexadecimal

Instructions in assembly language

Instructions in C++ #include <iostream.h>int main(){cout << "Hello World!" << endl;return 0;}

Instructions in SQL if ( $connect ) { // create the database. if ( ! @mysql_query ( "CREATE DATABASE `$database`" ) ) { die ( mysql_error() ); } else { echo “database created."; } } else { trigger_error ( mysql_error(), E_USER_ERROR ); }

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Introduction to Computer Systems Unit 1 - 1.57

Giving Instructions

Command line

GUI

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Introduction to Computer Systems Unit 1 - 1.58

Nowadays….

Standards have allowed rapid progress:• Proprietary

- Microsoft• Windows• Office

• Open source• Linux• Apache

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Introduction to Computer Systems Unit 1 - 1.59

Unit 1

Any questions?

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