Data Representation Flashcards

1
Q

Why do computers use binary instead of decimal?

A

Less arithmetic rules need to be built into the computer
There is either a voltage or no voltage so a drop in voltage doesn’t affect the data being sent
The components inside a computer have only 2 states eg on/off, positive/negative, voltage/no voltage therefore the 2 symbols (1 and 0) used in binary are perfect

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2
Q

What 2 codes is text stored as?

A

ASCII or UNICODE

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3
Q

What is an advantage of UNICODE?

A

Can represent more characters, ASCII limited to 128 characters. so no problem storing characters of non Latin based languages such as Greek, Chinese etc.

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4
Q

Disadvantage of UNICODE?

A

Takes up more memory than ASCII as 16 bits (2 bytes) per character are used.

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5
Q

What are integers?

A

Integers are positive and negative whole numbers (ie NO DECIMAL POINT)

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6
Q

What method is used to store negative integers?

A

twos compliment

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7
Q

What is Floating Point Representation?

A

This is when the number is stored using 2 parts, the MANTISSA and the EXPONENT

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8
Q

What is the mantissa?

A

MANTISSA is a binary fraction between 0 & 1 and is normally stored using 4 bytes. The size of the mantissa affects the ACCURACY of the number.

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9
Q

What is the exponent?

A

The EXPONENT is the power and is normally stored using 1 byte. The size of the exponent affects the RANGE of the numbers available.

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10
Q

What 2 ways are graphics stored?

A

Bitmap or Vector Graphics

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11
Q

What is bitmap?

A

is when the image is stored as a series of pixels and each pixel is stored as a number of bits, depending on the number of colours used.

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12
Q

Advantage of bitmap?

A

Each pixel can be edited individually (perfect for air brushing of photos)

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13
Q

Disadvantage of bitmap?

A

Uses a lot of memory because every pixel including white spaces is saved

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14
Q

What is Vector Graphics?

A

Vector graphics is when each object is stored by its attributes.

e.g – A line may be stored by the following attributes :
( Line – start x, start y, end x, end y, line thickness, line colour, line pattern)

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15
Q

Advantages of Vector?

A

Takes up less memory than bit-mapped.

  • Easy to resize, move and alter.
  • Images are resolution independent i.e. same image quality regardless of resolution of display or printer.
  • Quality of the image is not affected when enlarged.
  • Objects can be grouped together and then manipulated as a single object.
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16
Q

Disadvantage of Vector?

A

Cannot be edited at pixel level.

- Limited to mathematical shapes

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17
Q

What is bit depth?

A

This is the number of bits per pixel and it affects the number of colours an image can display.

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18
Q

resolution?

A

This is the number of dot (pixels) per inch

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19
Q

What is true colour?

A

This is when an image had 24 bits per pixels. This means the image can display
16.8 million colours

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20
Q

What is an address bus?

A

This holds the address of where the next instruction has to be read from or written to. It is uni- directional i.e. only goes in one direction from processor to memory

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21
Q

What will increasing the size of the address bus do?

A

The size of the address bus affects the amount of possible memory ( ie the number of addresses) increasing it increases the amount of possible memory. Increasing the size of the AB only improves the speed of the computer if the computer is struggling to run some software at a decent speed or if all of the software cannot be loaded at the one time.

22
Q

What is the data bus?

A

This allows the movement of data from the processor to memory and vice versa. Increasing the size of the data bus increases the amount of data which can be transferred at the one time therefore it improves the throughput (performance) of a computer.

23
Q

What is the control bus?

A

This bus is different from the AB + DB because each of the lines work independently ( ie they each have a different function). The lines on the AB + DB all work as a unit and carry data, the CB doesn’t.

24
Q

What is the Control Bus responsible for?

A

Read/Write lines – Read means read from memory location. Write means write to memory
location.
* Reset – This is a signal into the processor which when activated clears all internal registers,
aborts the current program and starts fetching and executing from a predefined place.

  • Clock – This is a pulse which sets the timing for processor activities.
  • Interrupt – Can stock the current process but can be ignored e.g no paper in printer.
  • Non-Maskable Interrupt – Resets the processor, cannot ignore it e.g power failure.
25
Q

What are the steps of the fetch-execute cycle?

A
  1. set up the AB with the address of the instruction to be carried out.
  2. Activate the read line on the CB.
  3. Data is transferred onto the DB and into the processor where it is decoded and executed.
26
Q

What are the steps of reading from memory? (buses)

A
  1. set up the AB with the address of the instruction to be carried out.
  2. Activate the read line on the CB.
  3. Data is transferred onto the DB and into the processor where it is decoded and executed.
27
Q

What are the steps for writing to memory? (buses)

A
  1. set up the AB with address of where data is to be written to.
  2. Data is transferred from the processor into the DB.
  3. Activate write on CB.
  4. Data is transferred from DB to memory location
28
Q

What is the ALU (arithmetic and logic unit) responsible for?

A

The Alu is responsible for all arithmetic calculations and logical operation involving AND, OR
etc

29
Q

What is the control unit responsible for?

A

The control unit is responsible for fetching, decoding and executing instructions which is the general internal operations of the processor. It controls the movement of data within the processor.

30
Q

What are the registers responsible for?

A

Registers are temporally storage locations within the processor

31
Q

What will increasing the number of registers do?

A

The higher the number of registers the better the throughput as internal fetch/execute is faster than having to fetch instruction from memory to the processor.

32
Q

How can you improve computer throughput?

A
  1. Increase the clock speed. The clock rate determines when instructions are fetched & executed, therefore increasing the clock rate increases the amount of data which can be processed per second.
  2. Increasing the size of the DB as this increases the amount of data which can be processed per cycle.
  3. Adding extra RAM. This helps if your computer is struggling to run some software at a decent speed or if all the software cannot be loaded at the same time especially if it is graphics or multimedia.
  4. Uses cache to speed up the transfer of data between memory and the processor
33
Q

What is Cache?

A

This is an area of memory that can reside (sit in) within the processor or sit between the processor and main memory.
This can be accessed very quickly by the CPU & so is a shorter fetch-execute cycle than from processor to the main memory.

34
Q

Explain the difference between interframe and intraframe compression, mentioning which one produces a smaller file size.

A

Interframe – stores the changes between each frame so produces a smaller file size
Intraframe – compresses each frame individually

35
Q

Describe File management and memory management carried out by an OS

A

File management – manages the use of backing storage by storing files and keeping a record of where they are
Memory management – manages main memory and allocates space in RAM to programs

36
Q

What law requires businesses to allow governing bodies to install surveillance software and hardware on their premises.

A

RIP A

37
Q

Describe 2 ways that businesses could make their use of computers more environmentally friendly.

A

Reducing electricity use by using energy efficient components/systems
Disposal/recycling of old equipment

38
Q

What is serial transmission?

A

Serial transmission is when data is sent one bit at a time along a straight wire, this is used over long distances because although slower than parallel transmission ‘data is not skewed’.

39
Q

What is parallel transmission?

A

Parallel transmission is when data is sent all at once along several wires.This is only used over short distances e.g connecting a printer to a PC because although faster than serial transmission data can become skewed over long distances.

40
Q

What is a buffer?

A
  • A buffer is an are of memory on a peripheral or on a interface (RAM)
41
Q

What is spooling?

A

Spooling is when data is stored on fast backing storage ( normally hard disc) and sent to the printer when it becomes available.

42
Q

What is an interface?

A

An interface is the hardware and software needed for communication between a processor and peripheral devices to compensate for the differences in their speeds, voltages, codes and amounts of data that are transferred at the one time.

43
Q

What are some functions of interfaces?

A
  • status signals – messages sent between the CPU and peripherals confirming whether they are ready to send/receive data or confirming the data has been received.
  • Data format conversion – changing the data format used by one device into a suitable format for another device. e.g. analogue to digital, serial to parallel etc.
  • Buffer – To store data temporarily to free up the faster processor.
  • Device selection – To be able to select the right device.
44
Q

What is the copyright, design and patents act?

A

You cannot use/copy other peoples materials without their permission.

45
Q

What is the computer misuse act?

A

This covers 2 things :- hacking and viruses.

46
Q

What is the data protection act?

A
  • Only allowed to see own information.
  • Must be kept secure and up to date.
  • Must register with data protection registrar.
  • Must only use data for purposes that have been registered.
  • Must only keep for time necessary.
47
Q

What is the function of the user interface?

A
  • Taking commands from input devices (keyboard/mouse).
    • Interpreting the commands.
    • Passing them on to the appropriate part of the os to be dealt with.
48
Q

What is the function of file management?

A

The file management system is responsible for creating, deleting, saving and updating of files and for keeping a directory of where files are stored.

49
Q

What is the function of memory management?

A
  • Checking there is enough RAM to load files.
    • Allocating a location in RAM for files.
    • Making sure no 2 programs (files) overlap.
50
Q

What is the function of Kernal (process management)

A

The main purpose of the kernel is job scheduling ie deciding which task gets the processor and when. Thus it is responsible for the smooth running of the computer. However the kernel is also responsible for keeping a note of the current status of any process when an interrupt is being dealt with.

51
Q

What is the function of input/output?

A

This is responsible for the actual transfer of data between processor to peripherals and for issuing the appropriate control signals to the peripherals.