Essential Computing Concepts © Math & Computer Department Foundation Program Fall 2006

Information System An Information System has the following parts: People: the most important part Hardware: consists of the equipment: keyboard, monitor, etc… Software: refers to the programs and its purpose is to convert data into information Data: unprocessed facts, and once processed, it becomes information Procedures: guidelines for people to follow when using software, hardware, and data

What is a Computer System? Hardware Software Equipment Programs

Central processing unit Computer System Central processing unit (CPU) Input Memory Output Hard Disk

Main Parts of a PC include: The System Unit CPU Memory or RAM (Temporary or Primary Storage) Input / Output Devices Secondary storage Devices Communication Devices ( Sends and receives data and programs from one computer or secondary storage device to another )

The System Unit The Motherboard, RAM, ROM, Hard Drive, Video Card and Power Supply are all inside the System Unit Ports are used to connect Input, Output, Secondary Storage and Communication devices to the System Unit

Picture of a Motherboard

The Motherboard Everything inside the system unit is connected to the motherboard Cards are plugged into slots on the Motherboard Example: Graphics Card, Sound Card, Network Card Hard drive is connected by cables CPU is a silicon chip on the motherboard

The CPU Central Processing Unit (or Processor) The brain of the computer Does all the Calculation and Processing Contains: Control Unit: interprets instructions Arithmetic Logic Unit (ALU): performs logical & arithmetic operations Cache memory: where the computer gets programs and data to execute

The speed of the CPU Measured in Hertz 1 Hertz = 1 cycle per second 1 cycle = 1 addition Megahertz = 1,000,000 cycles/second Gigahertz = 1,000,000,000 cycles/second Typical speed of modern CPU is 3 GHz

Random Access Memory (RAM) Electronic Components that temporarily store data (numbers, text, graphics, etc) being processed All programs and data are loaded into RAM Volatile – is deleted when the computer is switched off

Read Only Memory (ROM) A set of chips containing permanent (non-changeable) instructions to make the computer start working Can be read but cannot be written to ROM-BIOS – When the computer is switched on, these instructions check the computer and load the operating system into RAM Test is called POST Power On System Test

Input Devices Mouse Keyboard Scanner, video camera, light pen, joystick etc.

Output Devices Monitor/Screen (VDU – Visual Display Unit) Printers Laser printers Inkjet printers Plotters, speakers etc.

Secondary Storage Devices Provide Permanent Storage Common Storage Devices: Hard (Fixed) Disk : Consists of 1 or more rigid metal platters coated with a metal oxide material for recording. Floppy disk : Consists of thin, circular, flexible plastic disk with magnetic coating. CD (Compact Disk) : Flat, round, portable, metal storage. Uses laser technology. DVD (Digital Versatile Disk)

RAM CPU CD HARD DISK

Monitor Size and Resolution Different sizes: 17”, 19”, 21” Resolution is expressed in pixels (such as 800 x 600 or 1024 x 768) The higher the resolution, the more you can see. Larger monitors let you run at higher resolutions: e.g., 19” can run 1024 x 768 comfortably A graphics card (video display adapter) speeds processing

Ports and Buses Located on the system unit Used to connect peripherals (any outside device you can attach to your computer) Types: Serial Port Parallel Port Universal Serial Bus (USB)

Serial Ports Serial – data transferred bit by bit Normally two: COM1 and COM2 Used to connect devices such as modems

Parallel Ports Transfer more than one bit in one read/write Usually two: LPT1 and LPT2 Used to connect devices such as printers

Universal Serial Bus (USB) Serial – one bit in one read/write Used for devices like scanners, digital cameras and flash drives

Types of Computers Supercomputer: The fastest and most expensive high-capacity computers used by very large organizations Mainframe: Large computers, capable of great processing speeds and data storage Minicomputer: midrange computers used by medium-sized companies Microcomputer: Least powerful, small computers, but most widely used (desktop, Notebook or laptop, and Personal Digital Assistants)

Computer = Hardware + Software Hardware : refers to the Equipment Software : refers to the Programs A program is a set of instructions which tells the computer how to do its work

Types of Software System Software : Programs to control the operation of the computer E.g. Operating System (Windows, Unix, Linux etc), Utility Programs, Device Drivers Application Software : Programs for various applications E.g. Programs for word processing, business, scientific and other applications such as Microsoft Office which consists of MS Word, MS Excel etc.

Types of Software Hardware System Application E.g. Operating system such as Windows XP Hardware System S / W Back-end Application Front-end E.g. End-user programs such as MS Word

Connectivity Connectivity is the capability of your microcomputer to share information with other computers Central to the concept of connectivity: Network Network A communications system connecting two or more computers The largest network in the world is Internet

Data in files Is used to describe facts about something Common types of files: Document Worksheet Database Presentation

Data Storage A Bit (short for Binary digit) is the smallest unit of storage in the computer. It represents a pulse of electricity: Off = 0, On = 1 All numbers in the computer must be represented by Bits (0 or 1). We cannot do this with decimal numbers, so instead we use binary numbers Storage capacity: The amount of information that can be stored in a secondary storage device or in memory

Storage Capacity Temporary Storage Permanent Storage Random Access Memory (RAM) 256MB – 1GB Permanent Storage Floppy Disk 1.44 MB Hard Disk 40 – 120 GB CD (Compact Disk) about 700 MB DVD (Digital Versatile Disk) 8.5 GB DAT tapes 4 GB

Binary Numbering System Base 2 Consists of only two digits: 0 and 1 Converting a binary number to decimal (Example): 1101 (binary) = 1*23 + 1*22 + 0*21 + 1*20 = 1*8 + 1*4 + 0*2 + 1*1 = 8 + 4 + 0 + 1 = 13 (decimal)  

Bits & Bytes Bit: All computers work on a binary numbering system, i.e. they process data in one's or zero's. This 1 or 0 level of storage is called a bit. Byte: A byte consists of eight bits. Kilobyte: A kilobyte (KB) consists of 1024 bytes, approx 1,000 bytes. Megabyte: A megabyte (MB) consists of 1024 kilobytes approx 1,000,000 bytes. Gigabyte: A gigabyte (GB) consists of 1024 megabytes approx 1,000,000,000 bytes.

Representing Data The ASCII code (American Standard Code for Information Interchange) is used “A”  65 (01000001) “9”  57 (00111001) “?”  63 (00111111) “£”  163 (10100011) 1 Byte = 8 Bits. Data is represented in Bytes. One character requires 1 byte of storage. Storage Capacity is measured in Bytes (B, KB, MB, GB)

Occupational Health & Safety Using the computer for long periods of time, may pose risk to health. Ergonomics: Position of the monitor – Frame above screen should be level with eyes, so that you look slightly down. Distance should be less than an arm’s length. Avoid screen reflection and flickering. Posture of the user – Chair back upright, lower back supported, feet flat on floor, Forearms should be horizontal, wrists straight and task materials within comfortable reach of both hands. Preventive exercises should be done before commencing work, during work and after lunch breaks. Eye exercises: Take frequent short rests: Look away from screen towards objects 20-30 ft away, or look outside the window far out, or close your eyes. Muscle exercises: Do neck exercises. After every hour walk around, stretch all muscles and perform whatever relieves the feeling of muscle fatigue/strain Suggested reading: www.healthycomputing.com/office