Past Paper Thursday 13th June 2013 - Afternoon Flashcards

1
Q

State how many bytes are in a kilobyte? (1)

A

1 Kilobyte = 1024 bytes.

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2
Q

State how many kilobytes are in a gigabyte? (1)

A

1 gigabyte = 1024 kilobytes.

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3
Q

Describe the purpose of the ROM in a computer? (2)

A
  • Stores the boot program which is used to start the computer and load the operating system.
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4
Q

Describe the purpose of the RAM in a computer? (2)

A
  • Stores the parts of the OS programs that are running.

- Stores the data which is currently in use for access by the CPU.

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5
Q

State one difference between ROM and RAM, other than the size and the purpose? (1)

A
  • ROM is non-volatile and RAM is volatile.
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6
Q

A game console and a desktop computer are two different types of computer system. Describe how a game console is similar to a desktop computer, with reference to input, output and storage. (6)

A
Points may include:
• Game console has input devices,
usually specialised controllers but
also keyboards, microphones etc
similar to desktop computer
• Output is similar to desktop
computer on a screen and
speakers (sometimes using the
same standards eg HDMI, DVI)
• Game console usually has an
optical drive so that the software
to be run can be inserted. Many
also have a hard disk drive which
is the same as that used on a
desktop computer.
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7
Q

State the purpose of an input device in a computer system. (1)

A

To enter data from outside the system for processing.

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8
Q

State the purpose of an output device in a computer system. (1)

A

To return the results of processing

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9
Q

Describe two ways that the hardware in the computer terminal can be adapted so that blind customers can use it. (4)

A

Braille keyboard/input device
• As this is a familiar entry method for blind users
• Braille print out of transaction
• so that customer can review it.
• Use loudspeakers
• To provide audio feedback of actions taken (but not when entering card
details).

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10
Q

Explain why the technicians prefer to use hexidecimal. (2)

A
  • it is 4 bits per hex digit / straightforward to convert

• shorter number to remember/quicker to enter/less susceptible to error.

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11
Q

Display the most appropriate data type for each of these. (4)

  • Song
  • Length
  • TimesPlayed
  • Protected
A
  • Song - String
  • Length - Real
  • TimesPlayed - Interger
  • Protected - Boolean
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12
Q

The mp3 player can be connected to a computer from which songs can be added. The computer has a relational database with many tables. Explain, using an example, what is meant by an entity and how entities relate to the tables. (4)

A

An entity is a type of real world object (about which data is to be stored)
• e.g. Songs/albums/singers etc
• In the relational database each entity is modelled as a table
• Instances/examples/individuals of an entity are represented by
records/rows of the table
• Entities can have attributes
• .. valid example of attributes e.g. length of song
• Attributes of an entity are represented by fields/columns of the table

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13
Q

This is a computer program that simulates a 100m race. Each time the space bar is pressed the position of the player moves up by 1. When the position reaches 100, then the player has one.

CONST PlayerKey = " "
Position = 0 
REPEAT
  INPUT KeyPressed
  If KeyPressed = PlayerKey THEN
    Position = Position + 1
  END If
UNTIL Position = 100

State an example of a constant and variable in the algorithm above? (2)

A
  • Constant = PlayerKey

- Variable = Position or KeyPressed

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14
Q
CONST PlayerKey = " "
Position = 0 
REPEAT
  INPUT KeyPressed
  If KeyPressed = PlayerKey THEN
    Position = Position + 1
  END If
UNTIL Position = 100

State what is meant by selection and iteration using examples from the algorithm. (4)

A

Selection -
• A condition is used to decide whether code should be executed.
Example -
• Position = Position + 1 is only run if the IF condition is met.

Iteration - 
• Code is executed repeatedly.
Example -
• The code in the repeat loop will be run several times (until Position =
100).
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15
Q
CONST PlayerKey = " "
Position = 0 
REPEAT
  INPUT KeyPressed
  If KeyPressed = PlayerKey THEN
    Position = Position + 1
  END If
UNTIL Position = 100

To make the game more interesting, the rules have been changed. Each time the spacebar is pressed, the postion of the player will now move up by a random number. State two changes that need to be made to include this new rule and justify. (4)

A

Point
• Position = Position + 1 should be changed
• …so the increment is a random number
Justify
• The random number should be relatively small
• …so the game remains interesting
Point
• The end condition of the loop should be changed to UNTIL Position >
100 / check if position > 100 and if so change to 100
• … as the position may not reach exactly 100 due to the random number.
Justify
• seed/initialise random number generation
• … so that numbers generated appear random

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16
Q

Files are often compressed before they are sent over the internet.
- State what is meant by compression. (1)

A

Reduce the size of the file.

17
Q

State one advantage of compressing files before sending them over the internet. (1)

A

Transmits more quickly / uses less bandwidth

18
Q

State which type of compression is more useful and appropriate for downloading the source code of a large program. (3)

A

Type of compression = Lossless compression

Explanation = The code has to be exactly as it was originally written … or else it will not work.

19
Q

State which type of compression is more useful and appropriate for streaming a large video file. (3)

A

Type of compression = Lossy Compression
Explanation = Achieves higher compression/ smaller file size / faster streaming than
lossless. Video can still be viewed at lower quality (from the data compressed).

20
Q

Describe the difference between off the shelf and custom written software. (2)

A
  • Off the shelf software is available for anyone to acquire and use / commercially available
  • Custom written software is made especially for the school/ for a specific user
21
Q

Describe the difference between proprietary and open source software. (2)

A
  • Proprietary software cannot be copied/altered (without permission of the copyright owner)
  • Open source software can be modified (provided it remains open source)
22
Q

Explain the legal issues that the school should take in to account when choosing the software for ‘managing pupils’ attendance and examinations. (6)

A
Points may include:
• Must abide by software licence
• So for open source, the school
will be able to make
modifications/customisations to
exams system
• But will probably have to make
these modifications also
available to other users
• And credit all previous
contributors in the code
• Will have to purchase off the
shelf attendance package legally
• Software must be able to ensure
all legal data protection
requirements are met.
23
Q

Write an algorithm for a computer program that determines whether a triangle is an isosceles triangle.

  • The user inputs the lengths of the three sides as Length 1, Length 2 and Length 3.
  • If any two sides have the same length the program outputs “Isosceles”
  • Otherwise the program outputs “Not Isosceles” (5)
A
Example
 INPUT Length1
 INPUT Length2
 INPUT Length3
 IF Length1 = Length2 THEN
   Output “Isosceles”
 ELSE
   IF Length1 = Length3 THEN
     Output “Isosceles”
   ELSE
     IF Length2 = Length 3 THEN
       Output “Isosceles”
     ELSE
       OUTPUT “Not Isosceles”
     END IF
   END IF
 END IF
Award marks for:
• Inputting three lengths
• Comparing lengths in pairs
• … for all three ways correctly
• … outputting “Isosceles” for all valid cases
• … outputting “Not Isosceles” for all cases and only in cases where the
three lengths are different.