GCSE Computer Science (OCR) Questions & Answers

Arithmetic Logic Unit (ALU) - ANSWERSPerforms operations on data e.g. Addition, subtraction Control Unit (CU) - ANSWERSCoordinating activities of the CPU Registers - ANSWERSQuick, small stores of data within the CPU Memory Address Register (MAR) - ANSWERSHolds memory address for data or a instruction about to be used by the CPU Memory Data Register (MDR) - ANSWERSHolds actual data or instruction Accumulator - ANSWERSStores results of calculations in the ALU Program Counter (PC) - ANSWERSHolds memory address of the instruction for each cycle Fetch - ANSWERSThe next instruction is retrieved by CPU from main memory Decode - ANSWERSThe instruction is broken down and decided so computer can understand Execute - ANSWERSThe CPU performs what the instructions told Embedded System - ANSWERSA computer system built within a large device e.g. Camera, washer, car Volatile - ANSWERSMemory loses its data when power of Non-volatile - ANSWERSMemory retains its data when power is lost Random Access Memory (RAM) - ANSWERSRead/write - function is to load open programs and operating system data currently in use - volatile Read Only Memory (ROM) - ANSWERSCan only be read, can't be changed, stores essential programs to be run in order to boot the computer - non-volatile Cache - ANSWERSA type memory that stores copies of frequently used data, much faster than RAM, lower capacity - closer to CPU Buses - ANSWERSCollection of wires that carry signals between various components of the computer system Central Processing Unit (CPU) - ANSWERSProcesses all of the data and instructions that make the system work - can be effected by clock speed, number of cores, cache size Clock speed - ANSWERSHow fast the computer does the FDE cycle virtual memory - ANSWERSA memory management procedure needed when the RAM is full so a temporary section is made which acts like a part of RAM Flash memory - ANSWERSSolid state storage, non-volatile, more reliable/durable but can only be overwritten a limited number of times Graphics Processing Unit (GPU) - ANSWERSHandles graphics and image processing Optical storage - ANSWERSCD, DVD, Blue-ray ADV: cheap,easy to transport DIS: slow, less storage than hard drives, stored data degrades over time, cannot be written over Magnetic storage - ANSWERSHard drives ADV: fast access, stores large amounts of data, low cost DIS: not very portable, easily be broken Solid State storage - ANSWERSUSB, flash memory, SD ADV: fast, small, light, easily potable, quiet DIS: more expensive, storage capacity less, limited number erase/write cycles Cloud stotage - ANSWERSData is stored on multiple servers in a remote location ADV: secure, can be accessed anywhere, no need to buy DIS: needs internet, download and upload can be effected by internet connection, less control if data is held Operating System - ANSWERSessential software that links the hardware and other software together and generally manages the computer system Command-line Interface - ANSWERSText commands where user has to type in command Graphical User Interface (GUI) - ANSWERSuses icons and other visual indicators to navigate and issue commands Utility Software - ANSWERSmaintains a computer Defragmentation Software - ANSWERSreorganises data on the hard drive to put fragmented files back together and moves files to collect all the free space Backup Software - ANSWERSFull Backup - a copy is taken from from every file on the system Incremental Backup - only files created or edited since last backup are copied Compression Software - ANSWERSreduces file size so they take up less space on hard disk Encryption Software - ANSWERSscrambles data to stop others from accessing it Open Source Software - ANSWERSsource code is made freely available and users can modify it ADV: free, ,made for greater good, can be adapted DIS: small, buggy, security holes, no warranties, no customer support Proprietary Software - ANSWERSonly the compiled code is released and the source code is kept a secret ADV: warranties, well-tested, reliable, cheaper DIS: expensive, software may not fit user needs Personal Area Network (PAN) - ANSWERSwithin the range of an individual person Local Area Network (LAN) - ANSWERSa network that connects devices close to each other e.g. school, house Wide Area Network (WAN) - ANSWERSa network within a large geographical area e.g. internet Bandwidth - ANSWERSamount of data that can be transferred in a given time Network Interface Card (NIC) - ANSWERSallow a device to connect to a network Switch - ANSWERSconnect devices on a LAN Router - ANSWERSresponsible for transmitting data between networks