2 Name some typical tasks a computer is used for. Editing documentsCalculationsDrawingStoring dataControlling machines
3 What have these tasks got in common? InformationsimplicityrepetitionspeedaccuracyA computer is good at doing simple and repetitive tasks quickly and accurately. It deals primarily with information.
4 Some definitions and terms. Computer - information processorPersonal computer (micro-computer) - dedicated to one personPeripherals - devices ‘external’ to a computer and connected to it.Hardware - all equipment, computer and peripheralsComputer program - a set of instructions written in a form that the computer can understand. (eg Microsoft Word)Data - numbers and text. (eg. A drawing)Software - programs and data.Information - data processed into a useful form.Executing (running) a program - the instructions being carried out by the computer.
5 Characteristics of a Computer Think about what it is that makes a computer different from other machines.ability to perform high speed calculations.ability to take in and store information for future use.ability to take in and store a sequence of instructions.ability to obey a sequence of instructions.ability to use simple logical rules to make decisions for their own internal control.
6 Elements of a Computer System PeripheralDevicesKeyboardScreenMousePrinterPlotterModemFloppy disk driveHard diskCompact diskMagnetic tapeNetwork ‘card’ScannerComputerCPUProcessorInput/OutputunitMemory(RAM)ControlUnitALUdata busExercise: Classify the listed ‘peripherals’ as input, output, auxialliary storage or communication devices!
7 Information Storage and Retrieval Memory (Main Storage)often known as Random Access Memory (RAM)part of the Central Processing Unit (CPU) - inside computerusually volatile - loses its contents when power is turned offholds data and programs currently in use.very fast access to contents.electronic components (chips)relatively expensivelimited capacityWhat do you think are the problems of memory?
8 Information Storage and Retrieval Auxilliary (backing) Storageperipheral (external ) to CPUnon-volatile - does not require power to keep information.holds data not currently in useslower than memoryusually mechanical - disks (hard, CDROM, floppy, zip)and tapesless expensive per unit of storagemuch larger capacityWhat are the dis-advantages of auxilliary storage?