IGCSE Computer Science Paper 1 Crossword: 1.1 Number Systems and 1.2 Text, Sound and Images (Modules 28–41)
Name:
Date:
Class:
✎
Crossword
Read each clue and write the matching term in the grid. Numbers in brackets show the letters in each word.
1
2
3
4
5
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7
8
Across
- 2. A way to store negative integers in binary. The leftmost bit shows the sign: 0 means positive, 1 means negative. Positive numbers look the same as ordinary binary. Word 3 of: two's __________ (10)
- 6. Word 2 of the term in 4 Down: 8-___ _____ ________ (3)
- 7. Word 5 of the term in 5 Down: flip the ____ ____ ___ 1 (3)
- 8. Word 3 of the term in 5 Down: flip the ____ ____ ___ 1 (4)
Down
- 1. The agreed list of characters a system can use, with a unique binary code for each one, so every device reads the same code as the same ______. Word 2 of: _________ ___ (3)
- 2. Word 1 of the term in 1 Down: _________ ___ (9)
- 3. A denary number from 0 to 127 is written as ordinary binary, padded with zeros to 8 bits so the leftmost sign bit is 0. Numbers above 127 cannot be stored. Word 1 of: ________ two's __________ (8)
- 4. Look up each letter's ASCII code and write it as an 8-______ binary group, then join the groups in order. Example: A = 65 = 01000001. Word 4 of: 8-___ _____ ________ (8)
- 5. Write the positive value in 8-bit binary, flip every bit, ______ ______ 1. Example: 5 is 00000101, flip to 11111010, ______ 1 to get 11111011 (-5). Word 4 of: flip the ____ ____ ___ 1 (4)
- 7. A character set that gives each character a 7-bit code (128 characters), usually stored in 8 bits. Extended ______ uses 8 bits for 256 characters. (5)
Answer Key
IGCSE Computer Science Paper 1 · Modules 28–41
1S
2C
O
M
3P
L
E
M
4E
N
5T
H
O
T
N
H
A
S
C
E
R
6B
I
T
O
N
A
T
7A
D
D
C
8B
I
T
S
I
T
V
C
N
E
E
I
G
R
I
Across
2COMPLEMENT — A way to store negative integers in binary. The leftmost bit shows the sign: 0 means positive, 1 means negative. Positive numbers look the same as ordinary binary. Word 3 of: two's __________
6BIT — Word 2 of the term in 4 Down: 8-___ _____ ________
7ADD — Word 5 of the term in 5 Down: flip the ____ ____ ___ 1
8BITS — Word 3 of the term in 5 Down: flip the ____ ____ ___ 1
Down
1SET — The agreed list of characters a system can use, with a unique binary code for each one, so every device reads the same code as the same ______. Word 2 of: _________ ___
2CHARACTER — Word 1 of the term in 1 Down: _________ ___
3POSITIVE — A denary number from 0 to 127 is written as ordinary binary, padded with zeros to 8 bits so the leftmost sign bit is 0. Numbers above 127 cannot be stored. Word 1 of: ________ two's __________
4ENCODING — Look up each letter's ASCII code and write it as an 8-______ binary group, then join the groups in order. Example: A = 65 = 01000001. Word 4 of: 8-___ _____ ________
5THEN — Write the positive value in 8-bit binary, flip every bit, ______ ______ 1. Example: 5 is 00000101, flip to 11111010, ______ 1 to get 11111011 (-5). Word 4 of: flip the ____ ____ ___ 1
7ASCII — A character set that gives each character a 7-bit code (128 characters), usually stored in 8 bits. Extended ______ uses 8 bits for 256 characters.