Computers, Hardware, Operating Systems and Software Lecture 3

1
Computers, Hardware, Operating Systems and
Software Lecture 3
2
The Impact of Information Technology

• Manual Systems
• Manual methods of working
• Communicating face to face
• Inefficiencies

3
The Impact of Information Technology

• Manual Systems v Computerised Systems
• Disadvantages of manual systems
• Productivity
• Slower
• Risk of errors
• Less accesible
• Alterations
• Quality of output
• Bulk

4
The Impact of Information Technology

• The Computer
• A Computer is.
• Types of Computer
• Super Computer
• Mainframe
• Minicomputer
• PCs
• Portables
• Laptop, Notebook, plamtop.

5
The Impact of Information Technology - Hardware

• A Typical Computer
• Intel 1.8Ghz Pentium 4 Processor 3.5 (1.44MB)
  Floppy Disk Drive
• 40 GB hard disk drive 15 SVGA Monitor
• 56 kbps internal modem Logitech optical mouse
• 512k CPU Cache 2 serial ports, 1 parallel port,
  4 USB ports
• 128MB RAM Windows XP
• 8 Speed CD-Rom/DVD Combo Drive

6
The Impact of Information Technology - Hardware

• The Processor
• Arithmetic and logic unit
• Control Unit
• Main store of memory
• Single Chip plugged into mother board
• Intel, Amd, Cyrix.

7
The Impact of Information Technology - Hardware

• MHz and clock speed
• Signals are co-ordinated by a clock
• Cycle
• The number of cycles produced a second Megahertz
  (MHz)
• 1 MHz one million cycles per second
• 1 GHz one billion cycles per second
• Typical PC is 1.6GHz

8
The Impact of Information Technology - Hardware

• Memory
• Internal Store
• Programme instructions
• Input data
• Data that is ready for output

9
The Impact of Information Technology - Hardware

• Bits and Bytes
• on or off 1 or 0
• Each 1 or 0 is a bit
• Bits group together in 8 to form a character
  called a Byte
• Most PCs use 32bit processors
• The processing capacity is linked to a PCs
  memory
• Capacity is calculated in kilobytes
• 1 kilobytes 210 (1024)bytes
• 1 megabytes 220 bytes
• 1 gigabytes 230 bytes

10
The Impact of Information Technology - Hardware

• RAM
• RAM (Random Access Memory)
• RAM is volatile
• Typical Business PC 128 to 256 Megabytes
• RAM is extremely important
• Cache
• Cache is small but extremely fasted

11
The Impact of Information Technology - Hardware

• ROM
• ROM (Read Only Memory
• BIOS (basic input/output system)
• Part of the ROM Chip
• Hard Disks
• Direct Access
• Internal Hard Disk (Ave 30Gbs)
• Removable disk packs

12
The Impact of Information Technology - Hardware

• Floppy Disks
• Small 1.44Mb
• Zip Disk
• Removable Disk
• Tape Storage
• Much large capacity
• Backing storage
• More difficult to access

13
The Impact of Information Technology - Hardware

• CD-Rom
• 650/700 Megabytes of data
• Speed of a CD-ROM
• CD-Rs and CD-RWs
• Digital Versatile Disc DVD
• DVDs superseded the CD format
• Multimedia files
• 5 gigabyte of data
• Access at higher speeds

14
The Impact of Information Technology - Software

• Operating Systems
• Microsoft Windows O/S system
• UNIX Linux
• Interface between computer hardware, user and
  other software
• Initial setup
• Communicator between hardware and user
• Files from storage to memory
• File management

15
The Impact of Information Technology - Software

• Utilities
• Backup
• Programming Tools
• Compilers
• Assemblers
• Computer Aided Software Engineering (CASE) Tools

16
The Impact of Information Technology - Software

• Off-the-shelf
• Office type software
• Integrated accounting systems
• Bespoke Applications
• Tailor-made
• Relatively inexpensive

17
The Impact of Information Technology Data
Processing

• Data Processing in a computerised Environment
• A data file
• Collection of Records
• Similar Characteristics
• A record consisting of fields and a key field.
• Conventionally classified transaction files,
  masters file
• Reference Data, Cumulative transaction data
• Batch and real-time processing

18
The Impact of Information Technology Data
Processing

• Batch Processing
• Transactions being grouped and stored
• Processing in regular intervals
• Delays in processing
• Lack of up-to-date information
• E.g. Payroll

19
The Impact of Information Technology Data
Processing

• Batch Processing of Sales Ledger Application

20
The Impact of Information Technology Data
Processing

• Online Processing
• Input, Processed Immediately
• Real Time, Online
• Immediate
• Becoming the norm
• Direct Control of the main processor
• Also describes an active Internet connection
• E.g. Banking and Credit Cards, POS, Expedia.co.uk

21
The Impact of Information Technology Data
Processing
22
The Impact of Information Technology
Communications

• Digital means of digits or numbers. Digital
  information in a coded (binary) form.
• Analogue form uses variable signals

23
The Impact of Information Technology
Communications

• Modems and digital transmission
• New technologies require high speed transmission
  systems
• Existing analogue network
• MODEM (MOdulate DEModulate)
• Intergrated Systems Digital Networks (ISDN)
• Voice, data, video and fax

24
The Impact of Information Technology
Communications

• Asymmetric Digital Subscriber Line (ADSL)
• Ordinary copper wires
• simultaneous use of normal telephone services
• Mobile Communications
• Networks, Cellular Phones, Digital networks
• Higher transmission Speeds
• Less Likelihood of data corruption
• Office Activity on the move, email fax etc..

25
The Impact of Information Technology
Communications

• Mobile Services Available
• Messaging Services (SMS)
• Call Handling Services
• Corporate Services
• Internet Access
• Dual Mode Handsets
• Satellite Projects
• Limited by battery power

26
The Impact of Information Technology
Communications

• Voice Messaging Systems
• Recorded Messages
• Frustrating for callers with non-standard
  enquires
• Computer Telephony Interaction (CTI)
• Gather Information about callers

27
The Impact of Information Technology
Communications

• Computer Bulletin Boards
• Deposit messages
• Read what other people have left
• It becomes a way of keeping track on a project
• Videoconferencing
• Meetings
• Increasingly common with Internet and Webcams

28
The Impact of Information Technology
Communications

• Electronic Data Interchange (EDI)
• Avoiding the need for output
• Avoiding Re-keying of data
• Electronic Funds Transfer (EFT)
• Transfer funds
• E.g. to a supplier

29
The Impact of Information Technology
Communications

• Which Communication Tool?
• Conversation
• Meeting
• Presentation
• Telephone
• Facsimile
• Memorandum

30
The Impact of Information Technology
Client-Server Architecture

• Client-Server describes a network architecture
• A client is a machine which requests a service,
  for example a PC running a spreadsheet
  application which the user wishes to print out.
• A server is a machine which is dedicated to
  providing a particular function or service
  requested by a client. Servers include file
  servers (see slide 32), print servers etc.

31
The Impact of Information Technology
Client-Server Architecture

• A typical client-server system includes three
  hardware elements
• A central Server
• Local Servers
• Client Workstations

32
The Impact of Information Technology
Client-Server Architecture
33
The Impact of Information Technology
Client-Server Architecture

• Client-server systems aim to locate software
  where it is most efficient
• Corporate Application
• Local Application
• Client Application

34
The Impact of Information Technology
Client-Server Architecture

• The advantages of a client/server architecture
• Greater Resilience
• Scalability
• Shared Programs
• Shared work-loads
• Shared peripherals
• Communication
• Compatibility
• Flexibility

35
The Impact of Information Technology
Client-Server Architecture

• The disadvantages of a client/server architecture
• A Single Mainframe may be better
• Easier to control and maintain a centralised
  system
• Cheaper to tweak an existing mainframe
• Each location may need its own network
  administrator
• Duplication of information

36
The Impact of Information Technology
Client-Server Architecture

• Peer-to-Peer are generally simpler
• Local Area Networks and Wide Area Networks (LANs
  and WANs)
• Client-server and peer-to-peer describes
  relationship between devices
• LANs
• WANs

37
The Impact of Information Technology
Client-Server Architecture

• Differences between LAN and WAN
• Geographical area
• Telecommunications links
• Larger computer
• More terminals or computers linked
• gateways