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3 questions · 4 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.
Convert the hexadecimal number D5 to denary.
Award one mark for:
213
Why: 13 × 16 + 5 = 213 (1).
93
Why: Takes the right-hand digit as the 16s, so the value is wrong.
18
Why: Adds the two digits instead of multiplying the first by 16.
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 |
|---|---|---|
| 1100 0001 | Arithmetic shift right by 2 |
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1111 0000
Why: Every bit moves 2 places right, with copies of the sign bit (1) in from the left: both nibbles are correct (2).
0011 0000
Why: Fills the gap on the left with 0s, as a logical shift would, instead of copying the sign bit. The second nibble is correct (1); the first is not.
0000 0100
Why: Shifts the bits the wrong way. Neither nibble is correct.
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