IGCSE Computer Science Paper 1 Crossword: 2.2 Methods of Error Detection (Modules 155–164)
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
6
7
8
9
10
Across
- 3. ______ flipped bits at the corners of a rectangle keep every row and column parity correct, so a parity block check misses the ______. Only one ______ can be located reliably. Word 1 of: ____-______ _____ (4)
- 4. An extra ______ sent after a block of data bytes. Each of its bits is the parity bit for one column (bit position) taken down across all the data bytes in the block. Word 2 of: ______ ____ (4)
- 7. Word 2 of the term in 3 Across: ____-______ _____ (6)
- 8. A single parity check misses an error when an ______, because the count of 1s keeps the same parity. It also cannot show which bit is wrong. Word 2 of: ____ ______ of bits change (6)
- 10. ______ in the 7 data bits, then set the leftmost parity bit to 0 or 1 so the total number of 1s in the whole 8-bit byte matches the agreed rule (even or odd). Word 1 of: _____ the 1s (5)
Down
- 1. A ______ bit is added so the total number of 1s in the byte, including the ______ bit, is ______. Odd count of 1s in the data gives ______ bit 1; ______ count (______ 0) gives 0. Word 2 of: ____ ______ (6)
- 2. In a parity block, the ______ and the ______ that both fail their parity check cross at the bit that changed. Flip that bit to correct a single-bit error. Word 2 of: failed ___ and ______ (3)
- 5. Word 3 of the term in 3 Across: ____-______ _____ (5)
- 6. Word 4 of the term in 2 Down: failed ___ and ______ (6)
- 9. Word 1 of the term in 1 Down: ____ ______ (4)
Answer Key
IGCSE Computer Science Paper 1 · Modules 155–164
1P
2R
A
3F
O
U
R
W
I
T
4B
Y
T
5E
6C
R
7C
O
R
N
E
R
L
O
8N
U
M
B
9E
R
M
V
10C
O
U
N
T
E
N
Across
3FOUR — ______ flipped bits at the corners of a rectangle keep every row and column parity correct, so a parity block check misses the ______. Only one ______ can be located reliably. Word 1 of: ____-______ _____
4BYTE — An extra ______ sent after a block of data bytes. Each of its bits is the parity bit for one column (bit position) taken down across all the data bytes in the block. Word 2 of: ______ ____
7CORNER — Word 2 of the term in 3 Across: ____-______ _____
8NUMBER — A single parity check misses an error when an ______, because the count of 1s keeps the same parity. It also cannot show which bit is wrong. Word 2 of: ____ ______ of bits change
10COUNT — ______ in the 7 data bits, then set the leftmost parity bit to 0 or 1 so the total number of 1s in the whole 8-bit byte matches the agreed rule (even or odd). Word 1 of: _____ the 1s
Down
1PARITY — A ______ bit is added so the total number of 1s in the byte, including the ______ bit, is ______. Odd count of 1s in the data gives ______ bit 1; ______ count (______ 0) gives 0. Word 2 of: ____ ______
2ROW — In a parity block, the ______ and the ______ that both fail their parity check cross at the bit that changed. Flip that bit to correct a single-bit error. Word 2 of: failed ___ and ______
5ERROR — Word 3 of the term in 3 Across: ____-______ _____
6COLUMN — Word 4 of the term in 2 Down: failed ___ and ______
9EVEN — Word 1 of the term in 1 Down: ____ ______