Oxford Cambridge and RSA
GCSE (9-1) Computer Science
Computer Systems
J277/01
Topic: Unit 1.2 Character Sets
Time allowed: 20 minutes
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INSTRUCTIONS
Use black ink.
Answer all the questions.
INFORMATION
The total mark for this paper is 16.
The marks for each question are shown in brackets [ ].
Turn over
1
Computers use binary to represent all data, including text.
(a) Define the term 'Character Set'.
[2]
(b) The ASCII character set uses 7 bits to represent each character.
State the maximum number of different characters that can be represented using 7 bits.
[1]
2
A computer uses the ASCII character set.
In this character set, the capital letter 'A' is represented by the denary code 65.
(a) State the denary code for the capital letter 'E'.
[1]
(b) The computer stores the word STOP.
Calculate the total file size of this word in bits (assuming 7-bit ASCII is used).
Show your working.
[2]
Working:
Answer: bits
Turn over
3
Most modern computers and smartphones use the Unicode character set instead of ASCII.
(a) Explain one benefit of using Unicode instead of ASCII.
[2]
(b) Explain one drawback of using Unicode instead of ASCII.
[2]
4
A programmer is creating a messaging app.
They need to decide how to store the text messages.
(a) Explain how a character set is used to convert the key presses on a keyboard into binary data.
[3]
(b) Tick one box to identify which character set would be most suitable for an app that needs to send Emojis and Chinese symbols.