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AS- Level WJEC CS SAQ > 1.1 Hardware and communication > Flashcards

1.1 Hardware and communication Flashcards

1
Q

What is a computer architecture?

A

It is the parts inside a computer and how they are connected together.

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2
Q

What is the Von Neumann Architecture?

A

The type of architecture used in most computers today.

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3
Q

State 5 main components in the Von Neumann Architecture.

A
  1. Input
  2. Output
  3. Memory
  4. CPU (Central Processing Unit)
  5. Buses
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4
Q

State the purpose of output.

A

Output : A device that sends data from a computer to another device or user.

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5
Q

State the purpose of input.

A

Input : A device that introduces data into a computer system from outside it.

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6
Q

State the purpose of memory.

A

Memory : Stores instructions and data which are moved to and used by the CPU.

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7
Q

State the purpose of a CPU.

A

CPU (Central Processing Unit) : The brain of the computer which is split up into three parts.

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8
Q

State the purpose of buses.

A

Buses : Transfer data between components in the direction indicated. There are 3 types of buses used in a CPU.

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9
Q

Give 3 components a CPU is made up of.

A
  1. ALU (Arithmetic Logic Unit)
  2. Control unit
  3. Registers
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10
Q

State the purpose of an ALU.

A

ALU (Arithmetic Logic Unit) : Performs calculations (e.g. 5+2), comparisons (e.g. 5>2) and logical operations (e.g. AND, NOT, OR) as instructed by the control unit.

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11
Q

State the purpose of a Control unit.

A

Control Unit : Key part that controls operations inside the computer, based on programs instructions. It tells components what to do.

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12
Q

State the purpose of registers.

A

Registers: A block of memory used to temporarily stores a small amount of data.

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13
Q

State 3 types of buses.

A
  1. Data bus
  2. Address bus
  3. Control bus
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14
Q

What is a data bus?

A

Data Bus : Carries data and instructions.

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15
Q

What is an address bus?

A

Address Bus : Carries memory locations to be accessed.

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16
Q

What is a control bus?

A

Control Bus : Carries signals sent and received from the control unit which make sure all processes happen at the right time. Also carries commands.

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17
Q

What is memory?

A

Any storage used by a computer system.

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18
Q

What are the two types of storage?

A
  1. Primary (memory)
  2. Secondary (backup storage)
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19
Q

What are the 4 types of primary storage/memory?

A
  1. RAM (Random Access Memory)
  2. ROM (Read Only Memory)
  3. Registers
  4. Cache
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20
Q

What is main memory?

A
  1. Main Memory which stores programs that are currently being used.
  2. It is volatile so content is lost when power is off.
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21
Q

What is ROM?

A
  1. It stores permanent data that cannot be changed or deleted. It is non-volatile.
  2. Stores the bootstrap program (bios) which is needed to start up the computer.
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22
Q

What are registers?

A

Storage locations in the CPU i.e. Volatile, Fast Access & small capacity.

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23
Q

State 3 types of cache.

A
  1. Ram cache
  2. Disk cache
  3. Internet cache
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24
Q

What is Ram cache?

A

Ram Cache: Temporarily stores the most frequently used pieces of data. It supplies data to the CPU faster than normal RAM. Greatly reduces processor time.

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25
Q

What is Disk cache?

A

Disk cache: used to store data inputted from a disk. Speeds up retrieval of data from a disk.

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26
Q

What is Internet cache?

A

Web pages are stored so when they are viewed again they load faster.

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27
Q

State advantage (1) of using internet cache.

A

Previously viewed pages load quicker as they are read from a disk rather than downloading them again.

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28
Q

State an advantage of using internet cache (2).

A

Storing pages in anticipation means that if internet access cuts out, new pages can still be viewed.

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29
Q

What is secondary storage?

A

A device that is non-volatile and stores data in addition to main memory.

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30
Q

State 4 factors when comparing secondary storage.

A
  1. Speed
  2. Durability
  3. Portability
  4. Cost per storage unit
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31
Q

State 4 examples of secondary storage.

A
  1. Magnetic- internal/ external hard disk drives
  2. Solid State Drives and USB flash drives
  3. Optical (CD/ DVD/ Blu- ray) drives
  4. Tape drive
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32
Q

Evaluate hard disc drive (3).

A
  1. Very fast data transfer
  2. Low cost per byte of storage
  3. Physically small and can be stored securely in a fire proof safe.
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33
Q

Evaluate Magnetic tape storage (4).

A
  1. Access to tape is serial and slow
  2. Tape is relatively cheap but drives are expensive to purchase
  3. Tape is physically small and easily stored in a fire proof safe.
  4. Used widely by large companies historically.
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34
Q

Evaluate SSD/ pen drive storage (4).

A
  1. Very fast transfer
  2. Low cost
  3. Physically small and easily stored securely in a fire proof safe.
  4. Not suitable for a large company.
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35
Q

What is Parallelisation?

A

The use of parallel processing. Using more than one core in a CPU.

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36
Q

What is a core? (3)

A
  1. A single unit containing ALU and a control unit.
  2. Multiple cores can work at the same time.
  3. The more cores the more instructions per second that can be executed.
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37
Q

Are two cores twice as fast as one core?

A
  1. No, sometime is lost to organize which core will follow which instructions (this is called overhead).
  2. However the overhead is usually so small that dual-core processor is considered twice as fast as a single-core processor with the same clock speed.
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38
Q

What is the formula for calculating the time taken to execute a series of instructions?

A

no. of instructions/ clock speed of processor * no. of cores
Simply : n/ sp*c

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39
Q

What are the units for the results of the formula?

A

Gigahertz (GHz) which means a billion instructions can happen per second.

40
Q

What is clock cycle? (2)

A
  1. Time for 1 fetch - execute cycle.
  2. In a 2.5 GHz processor, a clock cycle will run 2.5 billion times.
41
Q

What is the Instruction cycle?

A

One instruction can 1 or more clock cycles to run.

42
Q

What is the Fetch execute cycle?

A

A series of steps followed by a CPU while a program is being run.

43
Q

One clock cycle equals?

A

One fetch-execute cycle

44
Q

Number of clock cycles per second on a
single core 3GHz processor?

A

The Fetch execute cycle would run up to three billion times each second.

45
Q

State 5 special purpose registers used in the fetch-execute cycle.

A
  1. Accumulator
  2. Instruction register (IR)
  3. Memory address register (MAR)
  4. Memory data register (MDR)
  5. Program counter (PC)
46
Q

What does an accumulator do?

A

Stores the intermediate results of
calculations or other processes.

47
Q

What does the instruction
register do?

A

Stores the instruction or process to be carried out on the data.

48
Q

What does the memory
address register do?

A

Stores the memory location that is to be accessed next. If an instruction is about to be accessed the MAR will store the same memory location as the program counter.

49
Q

What does the memory
data register do?

A

Stores data to be processed.

50
Q

What does the program
counter do?

A

Stores the memory location of the next instruction to be accessed.

51
Q

What Is the Fetch component of the Fetch
execute cycle? (3)

A
  1. A memory address is copied from the program counter to the memory address register. Which is sent along the address bus while a ‘read’ command is sent along the
    control bus.
  2. The instruction accessed in stage#1 is transmitted from the RAM to the CPU along the data register.
  3. When the instruction arrives at the CPU, it is divided into two parts. The operator is placed into the instruction registers; the operand is placed into the memory data register.
52
Q

What is the execute component of the fetch
execute cycle? (3)

A
  1. The instruction register is decoded so that the control unit knows what to do with the data in the data registers.
  2. The contents of the memory data register can now be processed according to the decoded instruction. What happens next depends on the instructions itself :
    * If a calculation is needed, the ALU will be used
    * If storage result is needed, data will be written to the accumulator.
  3. The contents of program counter are incremented (increased by 1) and ready for next instruction.
53
Q

What is an input device?

A

A device used to introduce data to the computer.

54
Q

What is an output device?

A

A device that allows data to leave the computer, usually to a person.

55
Q

State 3 input devices.

A
  1. Microphone
  2. Camera
  3. On- screen keyboard
56
Q

State 3 uses for microphones.

A
  1. Voice command systems: allows user to specify commands
  2. Voice dictation: converts speech to text
  3. Security: controlling access to a file or a physical room.
57
Q

State 4 challenges for speech recognition systems.

A
  1. Noisy environments
  2. Different accents or dialects
  3. Delineation (therefore read as their for)
  4. Homophones (buy/by/bye)
58
Q

State 3 uses for cameras.

A
  1. Facial recognition software: can recognize
    face in an image and identify it.
  2. Barcodes/ QR scanning software: alternative way to enter numbers or web addresses.
  3. Motion tracking software to activate image/video capture when something in the room moves.
59
Q

State 3 limitations for cameras.

A
  1. Finite resolution (number of pixels)
  2. Shutter speed (frames per second)
  3. Storage
60
Q

Give 3 uses for on- screen keyboards.

A
  1. A hybrid device as a screen also provides output.
  2. On- screen keyboards save space
  3. Limits the number of components that can break down.
61
Q

Give 3 limitations for on- screen keyboards.

A
  1. When space is limited, keys can be too small so words can be miss- typed.
  2. Predictive text and auto- correct are not always right.
  3. Often backup devices such as voice input must be included.
62
Q

What are 4 output devices ?

A
  1. Visual Display Unit (VDU)
  2. Speaker
  3. Light- emitting diode (LED)
  4. Printer
63
Q

What does a Visual
Display unit do?

A

A screen. Found in desktops, laptops, tablets, mobile phones, satellite navigation units, smart TV’s, digital cameras and many more.

64
Q

What does a speaker do?

A

Outputs sound, used in speech synthesis.

65
Q

What do LED’s do?

A

A single light on an electronic device. E.g. a VDU’s LED can flash to indicate that it is plugged in or a phone can subtlety signal that a message has been received.

66
Q

State 3 functions for a printer.

A
  1. Inkjet
  2. Laser
  3. Plotter
67
Q

What is an inkjet?

A

Uses ink.

68
Q

What is a laser?

A

Burns toner onto paper using a laser.

69
Q

What is a plotter?

A

Holds a pen in a mechanical hand, drawing accurately for technical documents like architectural plans.

70
Q

Why is secondary storage
used?

A

So the data is saved even if a computer is turned off. (i.e. Non- volatile).

71
Q

Name the most common
secondary storage.

A

The computer’s internal hard disk.

72
Q

Give 3 types of secondary storage.

A
  1. Magnetic (Hard Disk Drives)
  2. Optical (CD/DVD)
  3. Solid State Drives (SSD) or USB flash drives
73
Q

How does magnetic storage work? (5)

A
  1. A round disk called a platter is divided into billions of small areas.
  2. Each area can be individually magnetised.
  3. A read- write head is attached to the head accesses data from an area.
  4. Data is retrieved by direct access.
  5. The disk spins at 7,200 revolutions per min (rpm)
74
Q

What are optical storage devices?

A

Include CD’s, DVDs and BLU- Ray disks, are written and read from using lasers.

75
Q

How do optical disks work? (3)

A
  1. A disk spins and allows a laser to read the data from the correct location.
  2. It has 3 parts. A plastic disk on the bottom, reflective surface in middle and laser on top.
  3. The surface of the disk has billion of locations in which pits can be physically burned by a laser, or not burned, to represent either 1 or 0.
76
Q

What are Solid- state storage devices?

A

SSD, Flash drives/USB. They are very fast.

77
Q

How do Solid- state drives work? (2)

A
  1. They use electronic circuits, specifically transistors, to store data electronically.
  2. It has no moving parts so they are sturdier and quieter than others.
78
Q

What is fragmentation?

A

When a file is split up and stored in multiple physical locations on the disk.

79
Q

State consequences of fragmentation.

A

It greatly increases the disk access time.

80
Q

What is defragmentation? (2)

A
  1. The file segments are physically moved from one disk location to another.
  2. It minimises the gaps and stores the file, as much as possible, in a single track.
81
Q

What is a network?

A

It consists of more than one device (such as a computer) connected together to communicate and share resources.

82
Q

State 4 ways for signals to be sent between computers.

A
  1. Along cables
  2. Across WIFI networks
  3. Between microwave towers
  4. Between satellites
83
Q

State 3 ways for networks to be used.

A
  1. Sending emails
  2. Sharing files
  3. Connecting to devices such as a printers.
84
Q

Why are network standards important? (2)

A
  1. They allow compatibility between devices and software from different manufactures.
  2. Allows a network to easily share information.
85
Q

What is handshaking?

A

Sending and receiving devices check each others readiness to begin sending and receiving.

86
Q

What is the internet?

A

A worldwide interconnection of networks, the largest network on the planet.

87
Q

State 2 hardware needed for a wireless device.

A
  1. Wireless network card
  2. Wireless router (switch)
88
Q

What are protocols? (2)

A
  1. A set of rules a computer uses when communicating with another computer.
  2. Unless two computers are using the same protocol they will not be able to understand one another’s transmission.
89
Q

What are the 7 most common protocols?

A

1) HTTP : Hypertext Transfer Protocol

2) FTP : File Transfer Protocol

3) SMTP : Simple Mail Transfer Protocol

4) TCP/IP : Transfer Control Protocol Internet Protocol

5) IMAP : Internet Message Access Protocol

6) DHCP : Dynamic Host Configuration Protocol

7) UDP : User Datagram Protocol

90
Q

What does HTTP do?

A

Controls transmissions of web pages across
the internet.

91
Q

What does FTP do? (2)

A
  1. Allows the transfer of files across the internet.
  2. Used when uploading a file to a web server to make a web page.
92
Q

What does SMTP do?

A

Directs email message from server to server over the internet.

93
Q

What does TCP/IP do?

A

A suite of protocols that control how data is broken down for transmissions from a sender to receiver across a network.

94
Q

What does IMAP do?

A

Allows an email to be retrieved from a server to a computer.

95
Q

What does DHCP do?

A

Ensures each device connected to a network has a unique IP (internet Protocol) address.

96
Q

What does UDP do?

A

It sends data across the internet quicker than usual since no checking takes place to confirm that data was correctly received.

AS- Level WJEC CS SAQ (14 decks)

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