IGCSE Computer Studies-Syllabus 09.pdf - Ourpgs.com

COMPUTER STUDIES 0420 IGCSE 2009SECTION 5Hardware, systems and communicationsThe aim of this section is to draw together the experience of various kinds of hardware and typesof processing, and to examine the concepts of operating systems and communications.5.1 HardwareComputer, microcomputer,microprocessor, standard input andoutput devices, broad classes ofprocessor power;The functions and characteristics ofstorage media;The characteristics and performanceof a range of peripherals (includingcontrol and communication devices).Candidates should be able to identify the use of laptopcomputers (differences to desk top PCs); the use of CCTV;the use of microprocessors in everyday objects such ascameras, digital watches, etc. Candidates should be able todescribe suitable input and output devices in relation to therequirements of applications and the use of specialist inputand output devices (e.g. to help disabled people, devices tocommunicate with virtual reality systems, etc.).The functions and characteristics of storage media such asRAM, ROM, CD-ROM, CD – R/W, DVD, USB flash memory,disks and tapes need to be considered in relation to therequirements for applications.Candidates should be able to discuss the suitability ofdifferent peripherals for various applications.5.2 Systems and communicationsOperating system facilities:The nature of batch, online, multiaccess,real-time transactionprocessing, multitasking, networkand process-control operatingsystems;The form of interface between theoperating system and the user; useof command line and use ofgraphical user interfaces;Management of files; file directories;foldersPeripheral device control; use ofbuffers; interrupts and interruptpriorities; polling; handshaking;check sums.A real-time transaction processing system is an onlinesystem in which individual, discrete transactions areprocessed as they occur, an airline booking system and anonline stock control system are typical examples. This use ofthe term real time differs from its use in a real-time processcontrolsystem, in which physical quantities are continuouslymonitored and processed sufficiently rapidly to be capable ofinfluencing the sources of data.The need for and use of facilities to copy, move, list, printfiles. The use of sub-directories.For an interrupt system the external device or eventinterrupts the processor, whereas in a polling system theprocessor interrogates the device or status register. Thesetwo alternative methods have very different processingrequirements.Adding together all of the elements (for example, bytes) of ablock produces a single element known as the check sum.This can then be stored with the block and provides a checkwhen the block is transferred.12www.ourpgs.com