Computer Basics

Management Information Systems IMr. Greg VoglUganda Martyrs University13 February 2003

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Overview Motivation Definitions

Systems, Computers, Programs Hardware, Software, Data Types of Computers

Computer Functions and Components Input and Output Processing and Storage Communication

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Motivation Why learn Information Technology?

Use IT tools to achieve organizational goals Efficient and effective info. management Access information for decision-making Communication with customers, partners Keep up with the competition Personal satisfaction and enjoyment What are your reasons?

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Systems System

A group of interrelated components organized into a working unit to accomplish a goal (e.g. organism)

Information System A purposefully designed system that

brings equipment, procedures, and people together to manage information important to an organization's mission

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Computers and Programs Computer

Complex electronic machine used as a tool to input, process, store and output information

Program A list of instructions written by a programmer

that a computer follows to perform tasks Programming language

A set of instructions and rules of syntax that computers and programmers understand

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Hardware, Software, Data Hardware

Physical components of a computer system; parts or devices you can touch

Software Programs that control the operation of

the computer or perform a useful task Data

Unorganized, unprocessed information

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Types of Computers Supercomputer

A very fast computer usually used to process large amounts of scientific data

Mainframe A powerful large computer used by many

people in a large business or organisation Minicomputer

A powerful medium-sized multi-user computer Microcomputer or Personal Computer (PC)

A small computer usually used by one person

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Types of Microcomputers Workstation

A powerful, expensive computer for a professional in architecture, engineering etc.

Desktop computer Often found in offices and homes

Portable computer A small light-weight microcomputer that is

easily carried (“notebook” or “laptop”) Personal Digital Assistant (PDA)

A very small hand-held computer used for organising personal information and messages

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Types of Software System Software

Enables computer to control devices, run programs, communicate with users

Applications Software Enables people to do useful tasks e.g.

writing letters, balancing budgets Communications Software

Enables people and computers to communicate at a distance

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Types of Computer Users Computer technicians

People who build or fix computer equipment Systems analysts

People who plan and evaluate systems Programmers

People who write programs Users

People who use computers in their work

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Applications Software Word Processing (e.g. Microsoft Word)

Write formatted text documents Spreadsheets (e.g. Microsoft Excel)

Do calculations with tables of figures Databases (e.g. Microsoft Access)

Manipulate tables of interrelated data Presentations (e.g. Microsoft PowerPoint)

Give a slide show to present information Graphics (e.g. CorelDraw, Paint)

Edit photos, diagrams, drawings and pictures

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Computer Functions Input

Entering information into the computer Output

Displaying the results of processing Processing

“Thinking”: calculations, arithmetic, logic, searching, selecting, sorting, organising, etc.

Storage Saving information for later use

Communication Exchanging information with other devices

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Hardware Components Input

Keyboard, mouse, microphone, scanner Output

Monitor, printer, speakers Processing

Processor Storage

Memory, disk, tape Communication

Modem, network card, cables

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Keyboard Input device for typing Most keys have characters (letters,

numbers and symbols) Other keys are used for control and

navigation

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Mouse Input device used for pointing and

selecting Ball inside moves rollers to position

pointer on screen One to three buttons used to select Right button used to view a menu Pointing devices on portables: track

ball, track point, touch pad

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Scanner Input device for text and graphics Works similar to photocopier Optical Character Recognition (OCR)

software is used to input text in editable format

Different types include flatbed, sheet-fed and hand-held

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Monitor Output device displays text and

graphics on a TV-like screen using an array of pixels (coloured points)

Uses Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD)

Resolutions: VGA=640x480, XGA=800x600, SVGA=1024x768

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PrinterOutput device prints text and graphics onto paper

Inkjet printers Laser printers use heat to spray ink onto paper

use laser light and static electricity to melt toner (ink powder) onto paper

often in colour usually monochrome (black/white)

cheaper than laser printers cheaper per page and often faster than inkjet

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Audio Input and Output Microphone

Converts analog sound into digital input Speakers

Convert digital signals into analog sound output

Sound card Handles communication between

microphone/speakers and processor

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Processor Central Processing Unit (CPU)

“Brain” of computer that “thinks” Control Unit

Fetches, decodes and performs instructions Arithmetic-Logical Unit (ALU)

+, -, *, /, number comparisons Registers

Small, fast temporary data storage

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Storage: Bits and Bytes Analog information varies continuously Digital information varies discretely Computers store information digitally The smallest unit of information is a bit, or

binary digit (1=on, 0=off) Each character (letter, number, symbol) is

represented with 8 bits = 1 byte 8 bits can represent 28=256 characters

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Storage: Larger Units kilo = thousand (103 = 1,000) mega = million (106 = 1,000,000) giga = billion (109 = 1,000,000,000) 210 bytes = 1 kilobyte (KB) 220 bytes = 1 megabyte (MB) 230 bytes = 1 gigabyte (GB) Note that 210 = 1024 ~ 1000 = 103

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Types of Memory Random Access Memory (RAM)

Temporary memory while computer is on, for programs and data

Read-Only Memory (ROM) Permanent memory, for startup

Virtual Memory Part of the hard disk used as temporary

memory when the RAM is full

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Magnetic Disks Floppy disk (diskette)

Small magnetic circle in 3 ½” square plastic case

Removable; inserted into floppy drive Hard drive

Stack of magnetic platters (disks) Fixed inside computer case

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Optical Discs Compact Disc (CD)

Removable optical disc inserted into CD drive Used for storing data and digital music CD-ROMs are read-only, unchangeable CD-Rs are recordable, once CD-RWs are rewritable, many times

Digital Versatile Disc (DVD) Like CD but faster and holds more info. Used for storing data and digital videos

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Magnetic Tape Data is stored on a magnetically

coated plastic ribbon Similar to audio or video cassettes Large capacity but slow Primarily used for backup copies of

information on disks

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Comparing Storage MediaStorage Device

Speed Capacity (typical)

Cost (per MB)

Floppy Disk

Slowest 1.44 MB Highest

Hard Disk

Fastest 20-200 GB Medium

Compact Disc

Fast 700 MB Medium

Magnetic Tape

Slow 1-20 GB Lowest

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Modem Connects computer to phone line to:

send and receive faxes send and receive electronic mail connect to the Internet

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Network Card Connects a computer to a network Connected computers can share

printers and other peripherals Connected computers can share

information e.g. electronic mail