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Eduqas a-level computer science > Hardware and communication > Flashcards

Hardware and communication Flashcards

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1
Q

optical character recognition (OCR)

A

converts printed media into editable text documents using a scanner - allows you to change text on a printed document ( eg books)

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2
Q

optimal mark recognition (OMR)

A

based around a predefined form with areas where someone can mark multiple choice responses. scanner detects dark marks on page and notes position of them
(used for exams)

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3
Q

magnetic ink recognition (MICR)

A

uses in containing iron oxide and specific fonts so data written in the ink can be read by MICR reader - used for cheques so that only relevant text it scanned.

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4
Q

OCR problem

A

can be read wrong by the computer so must be proofread

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5
Q

OMR problem

A

if mark not dark enough or large enough, scanner may miss it

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6
Q

resistive touch screens

A

cheaper + made up of 2 thin transparent sheets
when pressure is applied the sheets touch each other and a voltage is recorded in that position

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7
Q

resistive touch screen problem

A

don’t provide as sharp of an image as capacitive screens and don’t allow for multiple touches at once

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8
Q

capacitive touch screens

A

more expensive but allows clearer image and multiple touches at once
utilise the fact the human body conduct electricity so when you touch screen you change electric field of area you touched - this is registered as a click and X,Y coords are sent to OS

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9
Q

capacitive touch screen problem

A

doesn’t work when wearing gloves or using item to touch screen.

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10
Q

voice input

A

microphone detects voice commands which will be interpreted by computer and carried out

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11
Q

voice input problem

A

set amount of commands that the computer is able to understand and carry out.

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12
Q

vocabulary dictation

A

users speak into microphone and computer tries to translate into text

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13
Q

vocabulary dictation pros

A

can be faster than keyboard input
reduces spelling mistake risk
hands free

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14
Q

vocabulary dictation cons

A

background noise interferes
speech impediment, strong accents etc won’t be understood as well
words that sound the same may be misinterpreted.

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15
Q

voiceprint recognition

A

process of capturing person’s voiceprint, digitising and storing the data on computer system
used in security systems by comparing voice prints

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16
Q

secondary storage (backing storage)

A

non-volatile, long term storage that is not directly accessed by CPU.
stores data not actively being used and takes longer to retrieve from SS than from memory
computer uses input and output channels to transfer data from secondary to primary storage when needed for processing

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17
Q

types of secondary storage media

A

optical storage (CD/DVD/Blue-ray)
magnetic storage
solid stage storage

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18
Q

optical storage

A

laser beams projected onto disk and if light is reflected then data is read as a 1 if not it’s a 0

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19
Q

magnetic storage

A

eg hard disk drives (HDD)
data stored using a read-write head and magnetic platter (disk)
good compromise between storage capacity, performance and cost

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20
Q

solid state storage

A

eg solid state drive (SSD) or flash drive
no moving parts, data stored on flash memory chips
has low power consumption and high speed access but more expensive than HDDs
RAM can retain its state after power disconnected

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21
Q

fragmentation

A

over time files split and stored on different parts of the disk -stored in non-sequential manner
takes longer for disk heads to move between parts of the file

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22
Q

defragmentation

A

files are physically rearranged on the disk so they are no longer fragmented and parts of each file are stored together. SSDs cannot be defragged

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23
Q

HTTP

A

hypertext transfer protocol
transfers images, videos etc over internet

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24
Q

FTP

A

file transfer protocol
transfers files across internet between client and server
often used for large files

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25
Q

SMTP

A

simple mail transfer protocol
send and receive messages

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26
Q

TCP/IP

A

transmission control protocol/internet protocol
group of protocols that control how data is broken down for transmission from sender to receiver - includes error checking

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27
Q

IMAP

A

internet messaging access protocol
after SMTP directs email to correct server IMAP allows it to be retrieved on a device

28
Q

DHCP

A

dynamic host configuration protocol
ensures each device connected to a network has a unique index (IPAddress)

29
Q

UDP

A

user datagram protocol
sends data across internet but without handshaking or error checking so it is quicker
used for live streaming especially gaming

30
Q

handshaking

A

signal sent from once device to the other in order to agree on a set of protocols to use before data is transferred

31
Q

computer network

A

a collection of interconnected computers that have the ability to communicate with one another either through wired (ethernet) or wireless (wifi) connections
can be a LAN or a WAN

32
Q

peer to peer network

A

no computer acts as a server - all computers must work together to fulfil the required task (broken down and split between computers)
known as distributed processing

33
Q

protocol

A

set of rules that governs communication between devices

34
Q

network interface card

A

responsible for placing packets onto network cables in form of electronic signals (or light bursts if cable is optical)
electric signals depend on physical protocols being used on network

35
Q

hub

A

packet sent to hub where it will be broadcasted to all other computers connected to hub
the more PCs connected = more traffic thus more collisions and corrupted packets

36
Q

switch

A

perform routing of packets from one port to another
when packet arrives switch determines which port has destination address (known as routing)
routes at the MAC address level rather than IP level

37
Q

MAC address

A

when packet arrives at a switch, it looks at the MAC address and forwards it to correct port

38
Q

routers

A
  • connects different segments of a LAN together
  • allows access to outside networks (WANs) eg the internet
  • routes based on IP address - sections of network can be assigned similar IP address ranges which provide router with more info to direct packet.
  • more powerful processor + is more expensive than switch as has to deal with more devices
39
Q

wireless access point (WAP)

A

device that allows wireless devices to connect to a wired network . WIC connects to a WAP

40
Q

wireless network security

A

can detect wireless network by sitting close by so security is high priority
use encryption and require special key in order to stop unauthorised users.

40
Q

wireless network issue

A

distance from the router, interference from other devices, bad weather etc can impact speed and quality of connection.
low wireless signal can cause packets to contain errors meaning data needs to be resent.

40
Q

components of Von Neumann computer system

A

arithmetic logic unit
control unit
registers
buses
cache/internal memory

41
Q

arithmetic logic unit (ALU)

A

processing of data as a result of arithmetic and logical operations
result stored in accumulator

42
Q

control unit (CU)

A

manages fetch/decode/execute cycle fetches each instruction in sequence, decodes and synchronises it by sending control signals to other parts of computer

43
Q

registers

A

eg MAR, MDR, CIR
a small, fast access temporary storage

44
Q

cache memory

A

small very fast memory placed near processor
can be accessed by CPU more quickly than RAM to execute frequently accessed instructions
when cache is full, least recently used data is discarded

45
Q

address bus

A

used to transmit addresses in RAM of next line of program code to be fetched or an input/output port where data is to be stored or loaded

46
Q

data bus

A

used to transfer program code between RAM and processor or input/output ports

47
Q

control bus

A

send control signals from processor to RAM memory or input/output ports to initiate data transfer
carries interrupt signals to processor to indicate hardware/software requires attention

48
Q

Von Neumann pros

A

as CU retrieves data and instruction in same manner from one memory, design and dev is easier and cheaper
memory organisation allows them to utilise memory’s whole capacity.

49
Q

Von Neumann cons

A

parallel implementation of a program not allowed due to sequential instruction processing
Von Neumann bottleneck - instructions can only be carried out one at a time and sequentially (can be minimised using cache memory)

50
Q

registers in FDE cycle

A

accumulator
memory address register
memory data register
program counter
current instruction register

51
Q

accumulator (ACC)

A

register that holds the results from the ALU

52
Q

memory address register (MAR)

A

either stored mem address of data to be fetched or address of data that has been fetched

53
Q

memory data register (MDR)

A

holds data after fetch cycle
acts as a buffer holding data until processor is ready to use it

54
Q

program counter (PC)

A

stored address of next instruction to be executed from memory
will increment at end of each task

55
Q

current instruction register (CIR)

A

holds instruction that is currently being executed.

56
Q

fetch, decode, execute cycle process

A
  • PC contains address of instruction to be fetched
  • address bus used to copy contents of PC to MAR
  • instruction at that location copied to MDR temporarily
  • contents of MDR copied to CIR
  • value in PC incremented by 1 so next instruction can be fetched
  • instruction decoded then executed sending out control signals to memory and input/output devices
57
Q

opcode

A

binary representation of instruction given to a computer

58
Q

operand

A

specifies the data to be manipulated

59
Q

parallel processing

A

multi-core systems that can split a task up into threads and processes it each thread simultaneously

60
Q

parallel processing pros

A

more instructions processed in shorter time
tasks can be shared to reduce load one each processor and avoid bottlenecks

61
Q

parallel processing cons

A

hard to write programs for multi-core processors
results from each needs to be combined at the end which adds to time taken to execute
not all tasks can be split

62
Q

multiplexor

A

allows multiple messages to be combined so they can be sent over a data link simultaneously

63
Q

time division multiplexing

A

allocates small time slices alternately for data from each of the input message streams

64
Q

frequency division multiplexing

A

sends diff messages simultaneously but using different transmission frequencies

Eduqas a-level computer science (12 decks)

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