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Computer Science A-Level > Hardware and Communication > Flashcards

Hardware and Communication Flashcards

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1
Q

Active System

A

have a small battery within the tag, and the device will transmit its identifier at regular intervals. Depending on the power supply, the range can be up to 200 metres. Commonly used in security tags in shops

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2
Q

Alt Text

A

appears on the screen as an ‘alternative’ if the image can’t be displayed, but it is also an accessibility feature as it is the text that is used by a screen reader

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3
Q

Amdahl’s Law

A

T(n)=T(1)(B+(1/n)(1-B))

estimated runtime in a multi-core processor

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4
Q

ADC

A

Analogue to Data Converter

creates digital sound signal in microphones

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5
Q

ALU

A

Arithmetic Logic Unit

performs all the mathematical calculations and logical operations in the CPU, used to perform calculations, make logical decisions and returns the answers to the accumulator

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6
Q

Arithmetic Pipeline

A

divides up an arithmetic operation into its individual steps and each step is performed overlapping the next step

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7
Q

Bandwidth

A

determines the amount of information the processor can process in a single instruction, measured in bits

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8
Q

Barcode

A

an extra digit or character added to the end of a long code, computed by applying an algorithm to the other digits. When the long code is entered, the check digit is calculated and compared to the check digit at the end of the code and if it doesn’t match, it isn’t validated

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9
Q

Bayer Filter

A

used in digital cameras to determine the colour of each pixel, this sits above the image sensor and provides an array of red, green, and blue filters, one for each photosite. There are twice as many green filters, as this matches the colour sensitivity of the human eye.

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10
Q

Benchmark Testing

A

involves measuring the performance and capacity of the CPU when doing tasks such as 3D rendering, floating point maths tests and file compression which take up a significant amount of memory

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11
Q

Biometrics

A

physical characteristics such as fingerprints, facial images, irises and voice

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12
Q

Biometric Spoofing

A

a term used to describe a method of fooling biometric scanners

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13
Q

Buffer

A

area of memory used in transfer of data between devices; each hardware device is assigned a buffer during system start-up

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14
Q

Bus

A

something that connects processors to another part of the computer

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15
Q

Address Bus

A

where the address of the data is communicated to main memory. The width (number of wires) defines the amount of physical memory that can be addressed

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16
Q

Control Bus

A

used to tell the memory or the device the operation is to be performed

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17
Q

Data Bus

A

a series of wires that connects the processor to the main memory (RAM) or cache memory. Can be used to read from or write to memory

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18
Q

FSB

A

Front Side Bus

the interface between CPU and memory, can only go as fast as clock speed, determines how quickly data can be sent from the CPU to the rest of the system

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19
Q

Byte Accessible

A

when locations can hold a byte of data instead of a bit

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20
Q

Cache Controller

A

a chip that manages retrieval, storage and delivery of data to and from cache memory or a hard disk

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21
Q

Cache Memory

A

very fast storage memory built into the CPU that is used to speed up the processing of instructions, holds frequently used instructions and data and is searched before the CPU searches main memory

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22
Q

L1 Cache

A

physically part of the CPU and is the smallest and fastest cache

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23
Q

L2 Cache

A

close to the CPU and main memory, is slightly larger and slower than L1 and is searched after the L1 cache

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24
Q

L3 Cache

A

in parallel archictecture, this can be accessed by all cores, is the largest and slowest core, instructions are searched for in here after searching the two cores, is still faster than the RAM

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25
Q

Central Processing Unit (CPU)

A

main processor that executes information in a computer

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26
Q

Chain

A

a series of clusters that make up a file, which can be scattered all over the hard disk

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27
Q

CISC Processor

A

Complex Instruction Set Computer Processor

includes a complete set of special purpose circuits that carry out variable sized instructions at very high speeds, reducing program size and the required number of memory cycles to execute the program

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28
Q

Clock

A

refers to a pulse or signal used to synchronise processes occurring within a computer, has a constant tick that switches between 1 and 0

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29
Q

Clock Speed

A

measured in either megahertz or gigahertz, depends on the number of ticks per second

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30
Q

Cluster (Disk)

A

group of sectors that are arranged next to each other on the same segments

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31
Q

Cluster (Servers)

A

where redundant servers use spare servers to take over if they go down

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32
Q

Computer

A

a machine that can be programmed to manipulate symbols, which responds to a specific set of instructions in a well-defined manner, executes a pre-recorded set of instructions and quickly stores and retrieves large amounts of data

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33
Q

Contemporary Processor Architecture

A

modern architecture concerning computer processing

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34
Q

Array Processing

A

where a processor performs computations on a vast array of data, only executing one instruction at a time on an array of data to enhance the computer’s performance

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35
Q

CPU Cache

A

a small, fast memory store located within the CPU which is searched before anywhere else and holds copies of the most frequently used data

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36
Q

Co-Processor

A

an additional processor used in some computer systems to perform specific tasks, generally mathematical ones that generally take up a lot of memory

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37
Q

GPU

A

Graphics Processing Unit

used to rapidly render detailed graphics

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38
Q

Maths Co-Processing

A

used to rapidly carry out floating point maths operations

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39
Q

Parallel Processing

A

takes place in computer systems with multiple cores, where each core executes instructions simultaneously. In theory, this would double the computer’s performance, however, this does not actually happen because some memory is used in allocating instructions to cores and sometimes instructions can’t be executed simultaneously because other instructions need to be executed first

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40
Q

Pipeline Execution

A

involves simultaneous execution of more than one instruction to increase performance, where multiple instructions are overlapped during execution

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41
Q

Control Unit

A

directs the flow of instructions and/or data/coordinates the other parts of the CPU/generates clock ticks or controls the clock

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42
Q

Cores

A

a complete CPU in its own right which can carry out any instructions

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43
Q

Delta Change Backup

A

only data changed since the previous back up is backed up, but the previous copy is also maintained in case it needs to be restored, useful as it is faster than completing a full backup

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44
Q

Demosaicing Algorithm

A

an algorithm in a digital camera that converts the analogue signal into binary form, so that each pixel is represented by a numerical value

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45
Q

DAC

A

Digital to Analogue Converter

a system that converts digital signal into analogue signal

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46
Q

Directory Table

A

stores the details of every file within that directory, which include the starting cluster of the file, the file name, the file extension, file attribute, date of creation and file size

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47
Q

Disk Defragmentation

A

where utilities juggle the contents of memory sectors around to keep files together as much as possible, making the computer run quickly and efficiently

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48
Q

Disk Fragmentation

A

where a file has been broken up across too many separate memory sectors, slowing down the access times of the file

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49
Q

Disk Thrashing

A

where the hard drive is being used for virtual memory because the RAM is full, giving the illusion of larger RAM

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50
Q

FAT

A

File Allocation Table

this keeps a record of every cluster on the hard disk and each record points to another record so a chain can be traversed

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51
Q

Flip-Flops

A

a type of circuit with two states, on and off, used to store data in solid state

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52
Q

Generation File Backup

A

involves storage of the three most recent versions of the master file, useful if one version is corrupted because the previous ones are still available but data should be stored off site in case of a disaster

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53
Q

Son Version

A

the most recent backup of the master file

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54
Q

Father Version

A

the second most recent backup of the master file

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55
Q

Grandfather Version

A

the third most recent backup of the master file

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56
Q

Harvard Architecture

A

similar to the Von Neumann model, except that it has two distinct sets of address and data buses, one of which is used for reading data from and writing data to the memory and the other is used for fetching instructions, solving the problem of the Von Neumann bottleneck

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57
Q

Incremental Backup

A

only backs up data that has changed and writes over older backups, useful as it saves storage space and is faster than full backup, but only allows the user to restore the most recent backup

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58
Q

Input Device

A

allows data to be inputted into a computer system

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59
Q

Biometric Device

A

software that uses biometric data such as fingerprints or irises

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60
Q

Braille Keyboard

A

a type of keyboard specifically designed for people who read Braille, with Braille characters on the keys instead of normal letters

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61
Q

Concept Keyboard

A

a keyboard with specific buttons instead of letters and numbers, often used in assistive and augmentative communication

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62
Q

Data Gloves

A

a wired glove used for inputting information, used to capture physical data such as the bending of the fingers

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63
Q

Digital Camera

A

used to capture images, these work by opening a shutter to allow light into the camera, focusing the light on an image sensor, which breaks the picture up into millions of pixels

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64
Q

Eye-Tracking Device

A

a form of assistive technology that is controlled by the eyes

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65
Q

Fingerprint Scanner

A

often used to access phones and computers and to authorise small payments, but are easily spoofed as fingerprints can be damaged by cuts and it is easy to acquire copies

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66
Q

Foot Switch

A

a form of assistive technology that allows the user to control input to a system through a series of pedals

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67
Q

Flatbed Scanner

A

allows users to scan a physical document such as a photograph, handwritten note, or important letter and save it as a digital bitmap image

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68
Q

Game Controller

A

a device used with video games or entertainment systems to provide input to a video game, typically to control an object or character in the game

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69
Q

Graphics Tablet

A

also known as a drawing tablet, this is used to create digital drawings with a special Stylus by pressing the tip on the tablet surface

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70
Q

Iris Scanner

A

an increasingly major part of security systems and one of the most secure forms of authentication, as the iris is protected by the cornea

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71
Q

Keyboard

A

allows a user to enter character data (numbers, letters, and symbols). It often has function keys or special purpose keys to perform common user tasks such as sending signals to control the volume or to switch between windows

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72
Q

Laser Scanner

A

used to scan barcodes and QR codes, can be small wired or wireless handheld devices, or larger fixed units, and some have multiple lasers to make them easier to use

73
Q

Light Pens

A

a handheld photosensitive device resembling a pen used to pass information to a computer

74
Q

Magnetic Stripe Card Reader

A

capable of reading the data on things such as hotel door access cards contain a magnetic strip that holds data

75
Q

MICR

A

Magnetic Ink Recognition

uses a combination of ink containing iron oxide and specific fonts so that data written using this ink can be read by an MICR. Only MICR ink can be picked up, everything else will be ignored, even stuff written over the top of the MICR ink. This is used almost exclusively for cheques

76
Q

Microphone

A

captures analogue sound waves and converts them into electronic signals

77
Q

Mouse

A

allows a user to ‘point and click’ to select icons, or to position the cursor on the screen

78
Q

NFC Reader

A

Near Field Communication Reader

reads data from an NFC tag, uses radio waves to read data from a bank card or mobile phone when the two devices are close to each other, allowing contactless payment

79
Q

OMR Scanner

A

Optical Mark Recognition Scanner

often used to input the answers or marks that a candidate has made on a multiple choice test paper

80
Q

QR Code Scanner

A

Quick Response Code Scanner

these do not use lasers; the codes are captured and read by taking an image of the QR code, either with a dedicated scanner, or by using a camera and app on a mobile device

81
Q

Radio Frequency Identification Tags

A

allows data to be transmitted wirelessly over radio waves. There are two parts to an RFID system: a tag and a reader. Use of radio signals means that the system does not require a line of sight between the tag and the reader. RFID tags are made up of an antenna, for receiving and transmitting the radio frequency signals, and a chip, which processes the signals. Each tag has a unique identifier and will often store some additional data in a non-volatile memory cell.

82
Q

Sensor

A

a device which detects or measures a physical property and records, indicates, or otherwise responds to it

83
Q

Accelerometer

A

an instrument for measuring the acceleration of a moving or vibrating body

84
Q

Ambient Light Sensor

A

a photodetector that is used to appropriately dim or brighten the device’s screen

85
Q

Barometer

A

an instrument used to measure atmospheric pressure, used in forecasting the weather and determining altitude

86
Q

CCD

A

Charge-Coupled Device

a light-sensitive integrated circuit that captures images by converting photons to electrons and breaks the image elements into pixels

87
Q

CMOS

A
88
Q

GPS Reciever

A

Global Positioning System Receiver

processes the signals broadcasted by GPS satellites

89
Q

Gyroscope

A

a device consisting of a wheel or disc mounted so that it can spin rapidly about an axis which is itself free to alter in direction. The orientation of the axis is not affected by tilting of the mounting, so gyroscopes can be used to provide stability or maintain a reference direction in navigation systems, automatic pilots, and stabilizers

90
Q

Image Sensor

A

an array of millions of photosites, which are light-sensitive elements that measure the intensity of light, therefore breaking the image up into millions of pixels

91
Q

Magnetometer

A

an instrument used for measuring magnetic forces, especially the earth’s magnetism

92
Q

Thermometer Proximity Sensor

A

a sensor able to detect the presence of nearby objects without any physical contact

93
Q

Sip and Puff Device

A

a pneumatic piece of assistive technology that allows the user to control computer systems by drawing or blowing air into a sensor reader, which can be used to switch things on and off, or control a wheelchair or keyboard

94
Q

Smart Card Reader

A

often found in retail shops, reads data taken from the integrated circuit chip found on a customers bank card to enable a transaction to take place

95
Q

Touchscreen

A

designed to both input and output data, allows the user to use their finger or a stylus to select icons, use an on-screen keyboard, and perform navigation tasks

96
Q

Capacative Touchscreen

A

much cheaper and are made of two thin transparent sheets, when these touch each other, a voltage is recorded at that position. A certain amount of pressure is needed to make the sheets touch. This does not provide as sharp an image as capacitive screens, nor do they allow for multiple touches

97
Q

Resistive Touchscreen

A

much cheaper and are made of two thin transparent sheets, when these touch each other, a voltage is recorded at that position. A certain amount of pressure is needed to make the sheets touch. This does not provide as sharp an image as capacitive screens, nor do they allow for multiple touches

98
Q

Trackpad

A

offers the same functionality as a mouse but the user controls the movement of the cursor using their fingers. It is commonly found on laptop computers

99
Q

Voice Recognition Software

A

a form of biometric software that can recognise the unique characteristics in someone’s voice, such as vocal tract, pitch and accent

100
Q

Vocabulary Dictation

A

can be used to input data into a computer system, where a user will speak into a microphone and the computer will try to change the spoken words into typed text. Vocabulary dictation is a popular interface as it is natural for people to communicate in this way. Specialist vocabularies are available with additional words for particular types of users, such as medical and financial users

101
Q

Voice Input

A

can be used to issue spoken commands to a computer system via a microphone, and the computer will try to interpret the commands and carry them out. This is different to vocabulary dictation as there is a set amount of commands tat the computer is able to carry out

102
Q

Voiceprint Recognition

A

the process of capturing a person’s voiceprint then digitising and storing this data on a computer system. This is often used in security systems, where a person may attempt to gain entry to a high security room. When entry is attempted, the voiceprint of that person is again captured. These two data items are compared, with entry being allowed if there is a match

103
Q

Webcam

A

a video camera that is connected to a computer or integrated in a device and allows its images to be seen online

104
Q

Instruction Pipeline

A

will pre-fetch the next instruction and data and store it in a register. As one instruction leaves the current instruction register (CIR), the next one is ready to be loaded and decoded. At any given point, there are instructions being fetched, decoded and executed.

105
Q

Interrupt

A

a signal to the CPU indicating that CPU time is required to deal with some event, can be generated by hardware, software and users

106
Q

Kernal

A

a part of the computer’s operating system that generally has complete control over everything in the system

107
Q

Latency

A

average amount of time taken for the other end of that link to respond

108
Q

Mass Storage Device

A

allows a computer to permanently retain large amounts of data and program between jobs, includes disk drives and tape drives

109
Q

Memory

A

allows a computer to store, at least temporarily, data, programs and immediate results

110
Q

Middleware

A

software that acts as a bridge between an operating system or database and applications, especially on a network

111
Q

Millennium Bug

A

a problem with some computers arising from an inability of the software to deal correctly with dates of 1 January 2000 or later

112
Q

Multi-Core Processor

A

an integrated circuit that has two or more processing cores, meaning it can theoretically carry out more than one instruction at once

113
Q

Output Device

A

allows data to be extracted from a computer system

114
Q

3D Printer

A

allows for three-dimensional designs on a computer to be printed in solid form

115
Q

Digital Screen

A

a form of display on either a stand-alone monitor or built-in screen

116
Q

Headphones

A

a pair of small loudspeaker devices worn on the ears for listening to audio signals

117
Q

Inkjet Printer

A

use liquid ink to produce black-and-white or colour prints, can often handle specialist paper and print at very high resolutions (with the ability to show a large amount of detail)

118
Q

Laser Printer

A

a type of printer that uses powdered ink called toner, that do not produce as high a quality of prints as inkjet printers

119
Q

LCD Screen

A

Liquid Crystal Display Screen

the most common display found in offices and on standard desktop and laptop computers, but are increasingly being phased out in favour of LEDs

120
Q

LED Screen

A

Light Emitting Diode Screen

a cheaper and more environmentally-friendly alternative to the LCD

121
Q

OLED Screen

A

Organic Light Emitting Diode Screen

a lighter and more flexible variant of the LED for mobile phone screens

122
Q

Plotter

A

a device that uses one or more pens to draw an image, commonplace in architectural and engineering practices

123
Q

Refreshable Braille Display

A

a form of assistive technology that displays characters as a series of dots formed by pins that protrude through the flat surface of the device, allowing people to access webpages or e-books by reading Braille

124
Q

Speakers

A

a device that generates sound waves from data being received from a sound card, often built into devices but can also be connected as external peripherals

125
Q

Overclocking

A

where the CPU’s clock is set to run faster that its original design. Whilst this may seem like a good idea, it can lead to overheating, therefore manufacturers do not endorse overclocking.

126
Q

Parallel Architecture

A

CPU with multiple cores

127
Q

Single-Core Processor

A

a core with only one processor

128
Q

Dual-Core Processor

A

a CPU with two distinct processor simultaneously working in the same integrated circuit, in theory is twice as fast as a single core processor

129
Q

Quad-Core Processor

A

a CPU with four distinct processors simultaneously working in the same integrated circuit, in theory is twice as fast as a dual-core processor

130
Q

Passive Device

A

do not contain a power supply. Instead, the device is powered by radio energy transmitted by the reader. The antenna collects the energy from the transmitter to activate the chip. The range of a passive system is up to 1 metre, and some systems require the reader to be very close to the tag

131
Q

Pipeline Flushing

A

a procedure executed by a CPU when it cannot ensure that it will correctly process its instruction pipeline in the next clock cycle

132
Q

Platter

A

the particles of the magnetic disk that are either positively or negatively charged

133
Q

QR Code

A

Quick Response Code

typically used to provide a link to a particular page on a website, or to provide a link to an email or app that holds, for example, purchase details for concert tickets or travel information such as train times and seat numbers for a journey, can store 7,089 numbers or 4,296 characters and because of the higher storage capacity, these are increasingly replacing barcodes

134
Q

RAM

A

Random Access Memory

the computer’s working memory, is volatile and editable, data is lost when the computer is powered down, allows multi-tasking. When the computer is on, it runs the operating system, all the other programs that are running and any data files that are in use

135
Q

DRAM

A

Dynamic Random Access Memory

a cheap form of RAM that holds data very densley

136
Q

SDRAM

A

Synchronous Dynamic Random Access Memory

improves performance through its pins, which sync up with data connection between the main memory and the microprocessor

137
Q

DDR SDRAM

A

Double Data Rate Synchronous Dynamic Random Access Memory

same as the SDRAM, but with twice the data

138
Q

ECC DRAM

A

Error Correcting Code Dynamic Random Access Memory

a type of DRAM that can find corrupted code and even fix it

139
Q

NVRAM

A

Non-Volatile Random Access Memory

a type of RAM that does not lose data when the computer is shut down

140
Q

Printer Memory

A

RAM built into a printer

141
Q

SRAM

A

Static Random Access Memory

uses flip-flops and transistors to be much faster than DRAM, but is also far smaller

142
Q

Video RAM

A

Video Random Access Memory

the memory a GPU uses to store the information it needs to render images on a display

143
Q

RISC

A

Reduced Instruction Set Computer Processing

a type of microprocessor that uses a small set of instructions of uniform length, generally executed in one clock cycle, simple to design and inexpensive, but is slow due to the computer having to repeatedly perform simple operations to execute a larger program

144
Q

Register

A

a storage location found in the CPU where data or control information is stored temporarily. Usually much faster to access that internal memory

145
Q

ACC

A

Accumulator

temporary stage register that has data from the arithmetic logic unit sent to it

146
Q

CIR

A

Current Instruction Register

the part of a CPU’s control unit that holds the instruction currently being executed

147
Q

Internal Memory

A

the memory that is available within the CPU

148
Q

Internal Register

A

these are used by the processor, in conjunction with fetching information from the RAM

149
Q

User Accessible Register

A

these are used within programmable instructions

150
Q

MAR

A

Memory Address Register

the CPU register that stores the memory address from which the data will be fetched to the CPU

151
Q

MDR/MBR

A

Memory Data Register/Memory Buffer Register

used for holding information (either program words or data words) that is in the process of being transferred from the memory to the central processor, or vice versa

152
Q

PC

A

Program Counter

a processor register that indicates where a computer is in its program sequence

153
Q

Status Register

A

indicates if a calculation has produced an overflow error

154
Q

Reserved Cluster

A

a cluster that is not available to store files

155
Q

Saving

A

copying data to secondary storage before it is switched off

156
Q

Secondary Storage

A

retains its contents when the computer switched off, stores both programs and data, and is used for saving and running programs as internal memory is volatile and data needs to be stored somewhere. There are three types of secondary storage

157
Q

Magnetic Storage

A

stores technology in magnetic mediums, in binary data, on a disk or tape that is coated with magnetic material. The magnetic medium is polarised, with North being 1 and South being 0. Examples include hard disk drives. Advantages include speed and the fact that the data can be read directly from any part of the hard disk. Disadvantages include durability and cost

158
Q

Optical Storage

A

uses laser technology and stores binary data on a reflective surface. Some areas reflect laser light and some don’t. If the laser is reflected, it represents 1, if not, it represents 0. Examples include CD, DVD and Blu-Ray. Advantages include storage, portability and speed. Disadvantages include durability, memory and the fact that data cannot be overwritten

159
Q

Solid State Storage/Flash Memory

A

this is called solid state as it doesn’t have any moving parts and is increasingly replacing magnetic and optical, stores binary data on semi-conductor material and different areas act as switches. If the switch is open, it represents 1, if closed, it represents 0. Examples include solid state drives. Advantages include durability, speed and power consumption. Disadvantages include storage and data cannot be overwritten unless it is deleted first

160
Q

Self-Modifying Code

A

code that alters its own instructions while it is executing

161
Q

Screen Reader

A

a form of assistive technology that reads the contents of the screen to the user

162
Q

Seek Time

A

average amount of time taken to read/write from a disk unit

163
Q

Simplex

A

data can only be sent in one direction; one node sends, the other receives

164
Q

Solid State Drive

A

the same as a hard disk, but uses flash memory and is often used in mobile devices

165
Q

Stored Program Concept

A

a program must be stored in main memory to be executed and its instructions are fetched one at a time and executed serially

166
Q

Switch

A

similar to a hub but only sends data to specific ports, greatly reducing data collisions

167
Q

Text-to-Screen Utilties

A

a form of assistive technology that reads the contents of the screen to the user

168
Q

Throughput

A

a measure of how many units of information a system can process in a given amount of time

169
Q

Toner

A

a type of powdered ink used in laser printers

170
Q

Trace Table

A

used to dry-run your program to see how the variables and output changed throughout the program

171
Q

Transistor

A

a semiconductor device with three connections, capable of amplification in addition to rectification

172
Q

Virtual Memory

A

when the system is running low on RAM, secondary storage is used so it seems like the program is running from RAM. A PC with limited RAM becomes slow if too many programs are running or too many large files are being loaded. Only some blocks of RAM are actively used at any given time, because the Operating system copies inactive data blocks from RAM to the hard disk and copies active data blocks from the hard disk to RAM

173
Q

Underclocking

A

where the CPU’s clock is set to run slower than its original design. This can lead to the the computer running very slowly

174
Q

Von Neumann Architecture

A

a computer architecture based on a 1945 description by John Von Neumann, with one memory unit and set of buses which is sued to access either data or programs, so is cheaper and simpler to produce, and an error in the program could corrupt all data and instructions

175
Q

Von Neumann Principle 1

A

instructions are executed in a linear sequence

176
Q

Von Neumann Principle 2

A

data and program instructions are stored together in the same memory and are indistinguishable

177
Q

Von Neumann Principle 3

A

the CPU is controlled by a single unit

178
Q

Von Neumann Bottleneck

A

the relatively slow speed at which data can be transferred between CPU and memory, compared with the amount of memory, causes the Von Neumann bottleneck. This limits the performance of the computer. To overcome this, we can use a range of techniques including memory caching, separate paths for data and memory and parallel processing

Computer Science A-Level (17 decks)

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