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Cambridge IGCSE™
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COMPUTER SCIENCE 0478/11
Paper 1 Computer Systems October/November 2025
1 hour 45 minutes
You must answer on the question paper.
No additional materials are needed.
INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● Calculators must not be used in this paper.
INFORMATION
● The total mark for this paper is 75.
● The number of marks for each question or part question is shown in brackets [ ].
● No marks will be awarded for using brand names of software packages or hardware.
This document has 12 pages.
DC (DE/CT) 343111/3
© UCLES 2025 [Turn over
, * 0000800000002 * DFD
DO NOT WRITE IN THIS MARGIN
2
, ,
1 A student has an electronic calculator. The calculator has a screen that displays the result of
calculations.
The calculator has 8-bit registers.
(a) State the highest denary number that could be stored in a single 8-bit register.
............................................................................................................................................. [1]
(b) Denary numbers are typed into the calculator. They are converted to binary numbers and
stored in the 8-bit registers.
DO NOT WRITE IN THIS MARGIN
The student types in the denary number 23 and the denary number 168.
Give the 8-bit binary numbers that are stored in the registers for these two denary numbers.
23
168
[2]
DO NOT WRITE IN THIS MARGIN
Working space ..........................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
(c) The result of a calculation that is stored in a register is the binary number 00001011
DO NOT WRITE IN THIS MARGIN
Give the denary number that will be displayed on the screen for this binary number.
00001011 ............................................................................................................................ [1]
Working space
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
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3
, ,
(d) Another result of a calculation that is stored in a register is the binary number 01000010
Give the denary number that will be displayed on the screen for this binary number.
01000010 ............................................................................................................................ [1]
Working space
...................................................................................................................................................
...................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
...................................................................................................................................................
(e) Two binary numbers stored in the registers are 01110110 and 00110000
Add the binary numbers using binary addition. Show all your working.
Give your answer in binary.
01110110
+ 00110000
DO NOT WRITE IN THIS MARGIN
[3]
(f) The result of a calculation could be a negative denary number.
State how the calculator could represent a negative denary number as a binary number.
............................................................................................................................................. [1]
(g) The electronic calculator is an example of an embedded system.
Explain why it is an example of an embedded system.
DO NOT WRITE IN THIS MARGIN
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [2]
DO NOT WRITE IN THIS MARGIN
Ĭ×ú¾Ġ´íÈõÏĪÅĊßü¸þ×
© UCLES 2025 ĬÄčüÔĦġĦÜðíġĬċīÒĝĂ
ĥŵĕµÕŵąõÅąÅÕÅÕõÕ
0478/11/O/N/25 [Turn over
, ,
Cambridge IGCSE™
¬Wz> 4mHuOªE^|6W
¬D|Y¨©tVwvKª
¥UU5U¥5eEEEEuEUEU
* 9 0 6 7 4 7 2 6 9 5 *
COMPUTER SCIENCE 0478/11
Paper 1 Computer Systems October/November 2025
1 hour 45 minutes
You must answer on the question paper.
No additional materials are needed.
INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● Calculators must not be used in this paper.
INFORMATION
● The total mark for this paper is 75.
● The number of marks for each question or part question is shown in brackets [ ].
● No marks will be awarded for using brand names of software packages or hardware.
This document has 12 pages.
DC (DE/CT) 343111/3
© UCLES 2025 [Turn over
, * 0000800000002 * DFD
DO NOT WRITE IN THIS MARGIN
2
, ,
1 A student has an electronic calculator. The calculator has a screen that displays the result of
calculations.
The calculator has 8-bit registers.
(a) State the highest denary number that could be stored in a single 8-bit register.
............................................................................................................................................. [1]
(b) Denary numbers are typed into the calculator. They are converted to binary numbers and
stored in the 8-bit registers.
DO NOT WRITE IN THIS MARGIN
The student types in the denary number 23 and the denary number 168.
Give the 8-bit binary numbers that are stored in the registers for these two denary numbers.
23
168
[2]
DO NOT WRITE IN THIS MARGIN
Working space ..........................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
(c) The result of a calculation that is stored in a register is the binary number 00001011
DO NOT WRITE IN THIS MARGIN
Give the denary number that will be displayed on the screen for this binary number.
00001011 ............................................................................................................................ [1]
Working space
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
ĬÕú¾Ġ´íÈõÏĪÅĊßú¸þ×
© UCLES 2025 ĬÄĎûÜĤĝĖÝĊĄè°ó¯ÒčĂ
ĥÅÅÕõµåÕĕąĕąÅµåĕĥÕ
0478/11/O/N/25
, * 0000800000003 * DFD
DO NOT WRITE IN THIS MARGIN
3
, ,
(d) Another result of a calculation that is stored in a register is the binary number 01000010
Give the denary number that will be displayed on the screen for this binary number.
01000010 ............................................................................................................................ [1]
Working space
...................................................................................................................................................
...................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
...................................................................................................................................................
(e) Two binary numbers stored in the registers are 01110110 and 00110000
Add the binary numbers using binary addition. Show all your working.
Give your answer in binary.
01110110
+ 00110000
DO NOT WRITE IN THIS MARGIN
[3]
(f) The result of a calculation could be a negative denary number.
State how the calculator could represent a negative denary number as a binary number.
............................................................................................................................................. [1]
(g) The electronic calculator is an example of an embedded system.
Explain why it is an example of an embedded system.
DO NOT WRITE IN THIS MARGIN
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [2]
DO NOT WRITE IN THIS MARGIN
Ĭ×ú¾Ġ´íÈõÏĪÅĊßü¸þ×
© UCLES 2025 ĬÄčüÔĦġĦÜðíġĬċīÒĝĂ
ĥŵĕµÕŵąõÅąÅÕÅÕõÕ
0478/11/O/N/25 [Turn over
