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3 questions · 5 marks
Computers manipulate binary patterns.
Convert the binary pattern 1010 0100 to denary.
Award one mark for:
164
Why: Correct: 128 + 32 + 4 = 164 (1).
37
Why: Reads the place values from the wrong end (the left-hand bit as 1), so the value is wrong.
3
Why: Counts the 1s instead of adding their place values.
Computer systems manipulate bit patterns.
Complete the table to show the result of the 8-bit binary addition.
| 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
|---|---|---|---|---|---|---|---|
| 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 |
| 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 |
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1101 0111
Why: 184 + 31 = 215, carrying where a column adds to 2: both nibbles are correct (2).
1010 0111
Why: Writes 0 for 1 + 1 but forgets to carry the 1. The second nibble is correct (1); the first is not.
1011 1111
Why: Writes 1 in every column with a 1 and never carries. Neither nibble is correct.
Computer systems manipulate bit patterns.
Complete the table with the result of applying the shift to the binary pattern.
| Binary pattern | Shift | 8-bit binary result |
|---|---|---|
| 1000 0111 | Logical shift right by 1 |
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
0100 0011
Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).
0100 0010
Why: A slip in the last bit. The first nibble is correct (1); the second is not.
0000 1110
Why: Shifts the bits the wrong way. Neither nibble is correct.
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