INTRODUCTION TO COMPUTERS Prepared and Presented by Doren Nedrick

What is a computer? A computer is an electronic device, operating under the instructions stored in its memory. It can:Accept data (input)Manipulate Data according to specified rules (processing) - CPUProduce results (output) from the processingStore the data and results for future use (storage)

Components of a computerThe basic components of a computer are:Hardware and Software.

HardwareAll the tangible parts of the computer (parts you can see and touch) and includes: The Mouse, KeyboardMonitorPrinterSystem unit

Software Programs used within a computer system (A set of instructions the computer carries out.)Software is intangible. Hardware is useless without Software and vice versa.

What is the Central Processing Unit CPU? The brain of the computer and controls how the rest of the computer works. It is assisted by the Control Unit (CU) and the arithmetic logic unit (ALU). The CU carries out the instructions in the software and directs the flow of data through the computer, the ALU performs the calculations and logic operation.

What are peripheral devices?Peripherals are all the hardware devices attached to the CPU - all the input, output, storage and communication devices attached to the CPU. Note the CPU is not a peripheral.

What are input Devices?Gets data into a computer. A mouse, a keyboard and a scanner are all input devices.

Output Devices Gets processed information out of a computer, for example to a printer, computer screen or even to speakers.

Memory and Storage Memory refers to data stored in the form of electronic chips while storage refers to memory on tapes and disks.Memory consists of one or more chips on the motherboard or some circuit board on the computer.

Memory stores three basic categories of items:The operating system and other system software that control or maintain the computer and its devices.Application programs that carry out a specific task such as word processing etc.The data being processed by the application programs and resulting information.

Types of Memory

Secondary Storage Known as backing or auxiliary storageThis is needed because RAM is limited in size and is temporarySecondary storage is of a non volatile nature and has larger storage capacity.These devices are able to store large volumes of information over a long period of timeExample floppy disk, CD ROM, hard disks, DVD and tape drives.

Secondary StorageSecondary Storage Devices fall under two main categoriesa. Direct Access Storage Device (DASD)- data can be accessed or stored without going through any other, b. Serial Access Storage Device-(SASD) - Data has to be read and written in a particular order

When data is entered it is stored in bytes. A Bit is a binary digit (0,1). Eight bits make one byte and a byte represents a character such as (&, A, 1, etc). Storage capacity is measured in:Kilobytes (KB) - Approximately 1 thousand bytes Megabytes (MB) - Approximately 1 million bytes Gigabytes (GB) - Approximately 1 billion bytes Terabytes (TB) - Approximately 1 trillion bytesIf a computer has RAM capacity of 256MB the computer handles 256 x 1,000,000 = 256,000,000 bytes or characters. In bits that would be 256,000,000 x 8.

Examples of Secondary Storage DevicesIt is necessary to format a disk in order to get it ready for use (storage/retrieval). Formatting or initializing the disk is the creation of the tracks and sectors. Usually disks are bought formatted. If not most operating systems contain formatting programs.

Importance of formattingWithout formatting there would be no way to know what data went with what. It would be like a library where the pages were not in books, but were scattered anywhere in the building.

Types of SoftwareSoftware is categorized according to purpose. There is: a. System Software and b. Application Software

System SoftwareManages the resources of the computer system. Two sub-categories are: a. Operating System- communicates between the hardware and the application programmes. (Win 98, Win ME, Win XP, MSDOS etc) b. Utility Programme - maintain the computer's health, i. Virus protection ii. Data Compression iii. Duplication of files/backing up/data recovery etc.

Application Softwarea. General Purpose - Used by anyone to do a number various tasks- Word Processing,Spreadsheet, Graphic Presentation, Communication and database b. Custom Written- built to suit the need of the customer - Like going to a tailor c. Specialized - created to complete specific tasks, (e.g. Payroll, AutoCAD, Electronics workbench)

Protective DevicesVoltage RegulatorSurge ProtectorUPS

Booting The process of starting a computer is known as booting. The first thing a computer does when it is booted is to check that it is working properly. It does this by following certain instructions held on a ROM chip known as the BIOS. You can often see this happening as various lines of text briefly appear on the computer monitor. It will then look for an operating system (OS) to tell it what to do next. The operating system is loaded from the disk to the computers random access memory (RAM).

File Management

Copy Files

Back up DataMaking copies of your file

Software Application

Operating System

Operating Windows Explorer

Word processing Software

Spreadsheet

Database Management

AutoCAD

Graphic Packages

Uses of the computer in industryAccounting/ Financial ApplicationsHuman Resource ApplicationsMaterial Inventory ManagementProcess Control RoboticsDecision Support SystemResearch and DevelopmentCAD/CAMCNC

Computer Networks