[Type text]
COMP2
AQA
A-level
COMPUTER SCIENCE
Paper 2
Time allowed: 2 hours 30 minutes
Materials
For Examiner’s Use
For this paper you must have:
a calculator. Questio Mark
n
Instructions 1
Use black ink or black ball-point pen. 2
Fill in the boxes at the top of this page. 3
Answer all questions. 4
You must answer the questions in the spaces provided. Do
5
not write outside the box around each page or on blank
pages. 6
If you need extra space for your answer(s), use the lined pages at the
7 end of
this book. Write the question number against your answer(s). 8
Do all rough work in this book. Cross through any work you 9
do not want to be marked.
10
Information 11
The marks for questions are shown in brackets. 12
The maximum mark for this paper is 100. 13
TOTAL
Advice
In some questions you are required to indicate your answer
by completely shading a lozenge alongside the appropriate
answer as shown.
If you want to change your answer you must cross out your original answer as
shown.
If you wish to return to an answer previously crossed out,
ring the answer you now wish to select as shown.
7517/2
, 2
Do not write
outside the
Answer all box
questions.
0 1 .1 Describe how a 12-bit unsigned binary integer such as
010010101110 can be converted directly into hexadecimal.
The method you describe must not involve converting into decimal.
[2 marks]
0 1 .2 State one reason why hexadecimal is often used in preference to binary.
[1 mark]
3
0 2 .1 A data communications system uses parallel data transmission.
Describe how parallel data transmission works.
[2 marks]
*02
*
, 3
Do not write
outside the
0 2 .2 State one advantage of serial data transmission over parallel data box
transmission.
[1 mark]
0 2 .3 Shade one lozenge to indicate which of these statements about data
communications systems is false.
[1 mark]
For a particular communications channel, the bit rate can
A
be higher than the baud rate.
B Latency is the rate at which signals on a wire or line can
change.
The bandwidth of a transmission medium is the range of
C signal frequencies that the medium can transmit without
a significant reduction in signal strength.
The greater the bandwidth of a transmission medium
D the higher the bit rate that can be achieved by a
communication system using it.
0 2 .4 State the purpose of the start bit in asynchronous serial transmission.
[1 mark]
0 2 .5 State the purpose of the stop bit in asynchronous serial transmission.
[1 mark]
6
*03
*
, 4
Do not write
outside the
Turn over ►
*03
*
COMP2
AQA
A-level
COMPUTER SCIENCE
Paper 2
Time allowed: 2 hours 30 minutes
Materials
For Examiner’s Use
For this paper you must have:
a calculator. Questio Mark
n
Instructions 1
Use black ink or black ball-point pen. 2
Fill in the boxes at the top of this page. 3
Answer all questions. 4
You must answer the questions in the spaces provided. Do
5
not write outside the box around each page or on blank
pages. 6
If you need extra space for your answer(s), use the lined pages at the
7 end of
this book. Write the question number against your answer(s). 8
Do all rough work in this book. Cross through any work you 9
do not want to be marked.
10
Information 11
The marks for questions are shown in brackets. 12
The maximum mark for this paper is 100. 13
TOTAL
Advice
In some questions you are required to indicate your answer
by completely shading a lozenge alongside the appropriate
answer as shown.
If you want to change your answer you must cross out your original answer as
shown.
If you wish to return to an answer previously crossed out,
ring the answer you now wish to select as shown.
7517/2
, 2
Do not write
outside the
Answer all box
questions.
0 1 .1 Describe how a 12-bit unsigned binary integer such as
010010101110 can be converted directly into hexadecimal.
The method you describe must not involve converting into decimal.
[2 marks]
0 1 .2 State one reason why hexadecimal is often used in preference to binary.
[1 mark]
3
0 2 .1 A data communications system uses parallel data transmission.
Describe how parallel data transmission works.
[2 marks]
*02
*
, 3
Do not write
outside the
0 2 .2 State one advantage of serial data transmission over parallel data box
transmission.
[1 mark]
0 2 .3 Shade one lozenge to indicate which of these statements about data
communications systems is false.
[1 mark]
For a particular communications channel, the bit rate can
A
be higher than the baud rate.
B Latency is the rate at which signals on a wire or line can
change.
The bandwidth of a transmission medium is the range of
C signal frequencies that the medium can transmit without
a significant reduction in signal strength.
The greater the bandwidth of a transmission medium
D the higher the bit rate that can be achieved by a
communication system using it.
0 2 .4 State the purpose of the start bit in asynchronous serial transmission.
[1 mark]
0 2 .5 State the purpose of the stop bit in asynchronous serial transmission.
[1 mark]
6
*03
*
, 4
Do not write
outside the
Turn over ►
*03
*
