Cambridge Assessment International Education
Cambridge International Advanced Subsidiary and Advanced Level
* 1 2 6 1 6 6 5 6 7 4 *
COMPUTER SCIENCE 9608/31
Paper 3 Advanced Theory May/June 2019
1 hour 30 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 13 printed pages and 3 blank pages.
DC (LK) 179424
© UCLES 2019 [Turn over
, 2
1 In a computer system, real numbers are stored using normalised floating-point representation
with:
• twelve bits for the mantissa
• four bits for the exponent.
The mantissa and exponent are both in two’s complement form.
(a) Calculate the denary value for the following binary floating-point number.
Show your working.
Mantissa Exponent
1 0 0 1 0 1 1 1 0 0 1 1 0 1 1 1
Working .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Answer ......................................................................................................................................
[3]
(b) Calculate the normalised floating-point representation of +1.5625 in this system.
Show your working.
Working .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Mantissa Exponent
[3]
© UCLES 2019 9608/31/M/J/19
, 3
(c) (i) Write the largest positive number that can be stored as a normalised floating-point
number using this format.
Mantissa Exponent
[2]
(ii) Write the smallest non-zero positive number that can be stored as a normalised
floating-point number using this format.
Mantissa Exponent
[2]
(d) The developer of a new programming language decides that all real numbers will now be
stored using 20-bit normalised floating-point representation. She must decide how many bits
to use for the mantissa and how many bits for the exponent.
Explain the trade-off between using either a large number of bits for the mantissa, or a large
number of bits for the exponent.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [3]
© UCLES 2019 9608/31/M/J/19 [Turn over
, 4
2 Cables connect the computers in a university admissions department in a star topology. The
server room contains the server and printer for the employees to use. The department has three
employees. Each employee has a computer connected to the star network.
(a) (i) Draw a diagram to show this topology.
[3]
(ii) Explain the benefits to the admissions department of using a star topology.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [4]
© UCLES 2019 9608/31/M/J/19
Cambridge International Advanced Subsidiary and Advanced Level
* 1 2 6 1 6 6 5 6 7 4 *
COMPUTER SCIENCE 9608/31
Paper 3 Advanced Theory May/June 2019
1 hour 30 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 13 printed pages and 3 blank pages.
DC (LK) 179424
© UCLES 2019 [Turn over
, 2
1 In a computer system, real numbers are stored using normalised floating-point representation
with:
• twelve bits for the mantissa
• four bits for the exponent.
The mantissa and exponent are both in two’s complement form.
(a) Calculate the denary value for the following binary floating-point number.
Show your working.
Mantissa Exponent
1 0 0 1 0 1 1 1 0 0 1 1 0 1 1 1
Working .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Answer ......................................................................................................................................
[3]
(b) Calculate the normalised floating-point representation of +1.5625 in this system.
Show your working.
Working .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Mantissa Exponent
[3]
© UCLES 2019 9608/31/M/J/19
, 3
(c) (i) Write the largest positive number that can be stored as a normalised floating-point
number using this format.
Mantissa Exponent
[2]
(ii) Write the smallest non-zero positive number that can be stored as a normalised
floating-point number using this format.
Mantissa Exponent
[2]
(d) The developer of a new programming language decides that all real numbers will now be
stored using 20-bit normalised floating-point representation. She must decide how many bits
to use for the mantissa and how many bits for the exponent.
Explain the trade-off between using either a large number of bits for the mantissa, or a large
number of bits for the exponent.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [3]
© UCLES 2019 9608/31/M/J/19 [Turn over
, 4
2 Cables connect the computers in a university admissions department in a star topology. The
server room contains the server and printer for the employees to use. The department has three
employees. Each employee has a computer connected to the star network.
(a) (i) Draw a diagram to show this topology.
[3]
(ii) Explain the benefits to the admissions department of using a star topology.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [4]
© UCLES 2019 9608/31/M/J/19
