2. Hardware Flashcards

1
Q

What does CPU stand for?

A

Central Processing Unit

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2
Q

What does the CPU do?

A

The hardware that executes programs and manages the rest of the hardware.

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3
Q

What are the two main parts of the CPU?

A

Control Unit - Sends electrical signals to components to control them
ALU - Carries out all the logic and calculations

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4
Q

What does ALU stand for?

A

Arithmetic Logic Unit

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5
Q

What things does the CPU need to access?

A
  • Main Memory (RAM)
  • Storage devices (Hard disk)
  • Input/Output Devices
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6
Q

How does the CPU access the things it needs to access?

A

A system of Buses (wires).

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7
Q

What is measured in Ghz?

A

The amount of instructions that can be carried out per second. (Clock speed)

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8
Q

How many calculations per second is 1 Ghz?

A

1 billion

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9
Q

What is a multi-core processor?

A

One component where two or more CPUs (processors) or ‘cores’ work together to improve the clock speed.

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10
Q

What is cache memory?

A

Memory close to the core processor with very rapid response. It is used to store instructions before they are executed and temporary data.

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11
Q

What is architecture?

A

How large the gap between transistors is and how many transistors are on a chip.

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12
Q

What is memory?

A

How computers store data and programs.

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13
Q

What is RAM?

A
  • ‘Main Memory’
  • Loads programs and data before running
  • Storing generated data before they are stored permanently
  • Allows CPU to access data from hard disk
  • Volatile -> Loses content when power is turned off
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14
Q

What is ROM?

A
  • Holds programs that start up the computer (boot up programs) and programs that have information about the hardware
  • Non-Volatile -> ‘Remembers’ state
  • Cannot easily be overwritten
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15
Q

What are the main differences between RAM and ROM?

A

RAM
• Loses its data when computer is switched off
• Temporary storage that is constantly being written to and read from
ROM
• Retains its data even when computer is switched off
• ‘Read only’ and cannot easily be changed by the program or user

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16
Q

What does RAM stand for?

A

Random Access Memory

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17
Q

What does ROM stand for?

A

Read Only Memory

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18
Q

What is virtual memory?

A

When there is not enough space on RAM, an area of the hard disk is used for temporary memory. This is, however, much slower than RAM.

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19
Q

What are some examples of magnetic devices?

A
  • Tape Drive / Digital Audio Tape
  • Hard Disk Drive
  • Floppy Disk Drive / Disk
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20
Q

How do magnetic devices work?

A

By setting an area of magnetic coated material to NS or EW setting. This can then be scanned by a read/write head.

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21
Q

What are some examples of optical devices?

A
  • CD - Rom, CD - R, CD - RW
  • DVD - Rom, DVD - R/RW/RAM
  • Blu-Ray
  • HD-DVD
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22
Q

How do optical devices work?

A

They are read using light - usually laser light (lighter and darker areas are detected). Commercially, troughs are cut into the disk surface. At home, colour change is used.

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23
Q

What are some examples of solid state technology?

A
  • Solid State Hard Disc
  • Memory Stick (USB)
  • Flash Memory (camera type)
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24
Q

How does solid state technology work?

A

There are no moving parts (solid state). Data is stored by applying a voltage to a grid of transistors and enabling or disabling current. NAND gates are used.

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25
Q

Why are magnetic drives not appropriate for portable devices?

A
Moving Parts
Slower data transfer times
Less robust
Larger in size
Uses more power than a solid state
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26
Q

What are buses?

A

The circuits/internal wiring of that connect the processor and main memory.

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27
Q

Remember to look at the diagram for how the CPU moves around instructions.

A

Pg 9 of textbook

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28
Q

Describe the fetch-execute cycle.

A

• Instruction fetched from main memory
• Control unit decodes instruction
• ALU executes instruction
(There may be storage in main memory after this)

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29
Q

What is the unit for clock speed?

A

Gigahertz (GHz)

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30
Q

What is clock speed?

A

The number of cycles per second that a system is capable of.

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31
Q

What is latency?

A

The time taken waiting for components to respond.

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32
Q

Summarise the purpose of the CPU.

A
  • Fetching data and instructions from main memory
  • Decoding and executing instructions
  • Performing calculations
  • Managing the movement of instructions and data to and from peripheral devices
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33
Q

What factors affect the performance of a computer/CPU?

A
  • Clock speed
  • Number of cores
  • Cache memory
  • Architecture - how large the gaps between transistors are and how many transistors there are
  • Speed of other components - can create bottlenecks
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34
Q

What does the control unit do?

A

Sends electrical signals to components to control them.

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35
Q

What does the ALU do?

A

Carries out all the logic and calculations.

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36
Q

What is a quad-core processor?

A

When there are 4 processing units within the CPU.

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37
Q

With what factors can different types of memory be compared?

A
  • Access speed
  • Price
  • Volatility
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38
Q

Why does the processor load programs into the main memory before executing them instead of getting them straight from the hard drive?

A

Access speed from the hard drive is very slow, so the main memory allows the computer to run faster.

39
Q

What is needed if many programs are running at once?

A

Lots of RAM.

40
Q

Sort these by access speed: Main memory, Cache, Virtual memory, Processor

A

1) Processor
2) Cache
3) Main memory
4) Virtual memory

41
Q

Give an example of volatile and non-volatile memory.

A

Volatile: RAM

Non-volatile: Hard disk

42
Q

What is the bootstrap loader?

A
  • The piece of software that loads the operating system.

* It’s the first program that is loaded into main memory from ROM when a computer is switched on.

43
Q

What is secondary storage?

A
  • Devices such as hard disks and memory sticks which are not the main memory.
  • They are long term and non-volatile.

(Basically any storage that is not main memory)

44
Q

What is the need for secondary storage?

A

To allow files to be stored for a long period of time. Main memory can’t do this.

45
Q

Describe how a program is loaded.

A
  • Program is loaded into main memory
  • The processor is given the address of the program in main memory
  • The processor can run the program instruction by instruction
  • Each time the processor fetches an instruction, decodes it, and then runs it
45
Q

What is the fetch-execute cycle?

A

The cycle that the CPU goes through as it fetches instructions from memory, decodes them and executes them. This repeats.

45
Q

What is the primary memory?

A

Main memory (RAM)

45
Q

What factors must be considered when picking a type of secondary storage for a specific purpose?

A
  • Capacity
  • Access speed
  • Portability
  • Durability
  • Reliability
46
Q

What are some common secondary storage types?

A
  • Optical
  • Magnetic
  • Solid state
47
Q

What is the reliability of a storage technology?

A

How long it will last.

48
Q

What is the durability of a storage technology?

A

How easily it is damaged (e.g. by dropping)

49
Q

Evaluate magnetic memory in terms of cost, capacity, access speed, portability, durability and reliability.

A
  • Cost: Cheap
  • Capacity: High
  • Speed: Slow
  • Portability: Usually not very portable
  • Durability: Vulnerable to movement, heat and magnetic fields
  • Reliability: Very good
50
Q

Evaluate optical memory in terms of cost, capacity, access speed, portability, durability and reliability.

A
  • Cost: Cheap
  • Capacity: Low
  • Speed: Very slow
  • Portability: Portable
  • Durability: Not too durable -> Not good for long term
  • Reliability: Good, but degrades over time
51
Q

Evaluate solid state memory in terms of cost, capacity, access speed, portability, durability and reliability.

A
  • Cost: Expensive
  • Capacity: Medium
  • Speed: Fast
  • Portability: Portable (except internal solid state / flash storage)
  • Durability: Very durable
  • Reliability: Very reliable
52
Q

Aside from portable storage such as USB drives, what can solid state memory be used for?

A
  • As a replacement for a hard disk in notebooks and tablets (internal solid state) or cameras and phones (memory cards) since it is a non-volatile type of RAM.
  • It can’t be used as a replacement for the main memory since the access speed is too slow.
53
Q

What is the processor?

A

The component in the computer that fetches, decodes and executes instructions.

54
Q

What is flash memory?

A

Basically, it is solid state memory, so it has no moving parts. The two terms are used synonymously sometimes.

55
Q

Compare the different types of storage by capacity?

A

Optical: Low
Solid state / Flash: Medium
Magnetic: High

56
Q

Describe how memory changes are advancing computers.

A
  • Capacity and density are increasing -> Increased number of transistors -> Doubling every 12 to 17 months
  • Speed -> Flash memory is replacing magnetic hard disks
  • Cost of memory decreasing
57
Q

What is an input device?

A

Any device that helps to input data into a computer.

58
Q

What is an output device?

A

Any device that outputs data from the computer to the user.

59
Q

How does a keyboard work?

A

Pressing a key generates a character code which is sent to the computer.

60
Q

How does a mouse work?

A

The mouse detects movements using either a ball or a reflected light source under the mouse.

61
Q

What is OMR and how does it work?

A
  • Optical Mark Recognition is used for detecting answers on multiple-choice tests, forms and lottery tickets.
  • Works by reflecting light off the boxes, which reflect less light if they are shaded.
62
Q

What is OCR and how does it work?

A
  • Optical Character Recognition is similar to OMR, but is used to convert markings into text
  • Works by reflecting light off the markings
63
Q

What is a sip-and-puff switch?

A

An assistive input device which detects breathing in order to control a computer for a disabled person.

64
Q

Name two types of monitor.

A
  • CRT Monitor - Cathode Ray Tube

* TFT Monitor - Thin Film Transistor

65
Q

What is a CRT monitor and where is it used?

A
  • Cathode Ray Tube Monitor
  • Heavy, old-fashioned monitor that takes up a lot of space
  • Used only in places like factories because they are more robust
66
Q

What is a TFT monitor and where is it used?

A
  • Thin Film Transistor Monitor

* Newer, thinner type of screen which most people have at home on laptops

67
Q

What is LCD technology?

A

Liquid Crystal Display - an earlier version of TFT screens

68
Q

Name four types of printer.

A
  • Inkjet printer
  • Laser printer
  • Dot-matrix printer
  • Braille printer
69
Q

How does an inkjet printer work and what are the advantages and disadvantages?

A
  • Works by spraying ink onto the page
  • Advantages: Good for low cost printing of text
  • Disadvantages: Slow, Smudged by highlighter
70
Q

How does a laser printer work and what are the advantages and disadvantages?

A
  • Laser beam is moved along page, creating static charge. Toner powder is attracted to this and is sealed by heat rollers.
  • Advantages: Faster, Quieter, Doesn’t smudge, Better images
  • Disadvantages: Expensive
71
Q

What is a dot-matrix printer and how does it work?

A
  • Printers which existed before inkjet and laser printers

* Work like a typewriter as a print head has to strike the paper through an ink ribbon to print text

72
Q

What is a Braille printer?

A

An impact printer that creates raised dots to allow blind people to read.

73
Q

What is an actuator?

A

A device that performs some sort of action (based on inputs). E.g. A voice sensor might trigger a motor to close some curtains

77
Q

Give some examples of inputs in a supermarket checkout.

A
  • Barcode scanner
  • Scales
  • Touch-screen
  • Keypad
  • Chip & pin reader
  • Magnetic stripe reader
78
Q

Give some examples of outputs in a supermarket checkout.

A
  • LED display
  • Receipt printer
  • Speaker
  • Touch-screen
79
Q

Give some examples of inputs in an automated home for a disabled person.

A
  • Microphone
  • Pressure sensor
  • Movement sensor
  • Digital camera
  • Touch-screen
80
Q

Give some examples of outputs in an automated home for a disabled person.

A
  • Lights
  • Motors
  • Monitor
  • Speakers
  • Touch-screen
  • Switches
81
Q

Give some examples of inputs for monitoring a patient in hospital.

A
  • Heart rate sensor
  • Blood pressure sensor
  • Breathing sensor
  • Temperature sensor
  • Touch-screen
  • Buttons
82
Q

Give some examples of outputs for monitoring a patient in hospital.

A
  • Warning lights
  • Speakers
  • Monitor
  • Printer
  • Touch-screen
  • LED display
83
Q

What is a Boolean expression?

A

An expression that is either true or false (e.g. X=10)

84
Q

What is a truth table?

A

A table that shows all the possible combinations of inputs and their logical
output value.

85
Q

What are the main logical operators?

A

AND, OR, NOT

86
Q

What is a logic diagram?

A

A diagram of a circuit showing logic gates with inputs and the output these
generate.

87
Q

What is a transistor?

A

A tiny switch that can be set to on or off.

88
Q

Why do computers use binary?

A

They contain thousands of transistors which can be set to either on or off.

89
Q

Remember to revise truth tables.

A

Pg 27 of textbook.

90
Q

What is the circuit symbol for an AND gate?

A

A D shape.

See Pg 28 of textbook

91
Q

What is the circuit symbol for an OR gate?

A

A D shape with a curved left edge.

See Pg 28 of textbook

92
Q

What is the circuit symbol for a NOT gate?

A

A triangle with a circle after the point.

See Pg 28 of textbook

93
Q

How can an AND gate symbol be turned into a NANAD gate symbol?

A

A small circle is added just after the symbol.

94
Q

What is the best way to complete a table for a complex logic gate, like a NAND gate?

A

Work through it stage by stag. E.g. Write the results of AND first, and then reverse these to get NAND