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4 questions · 7 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.
Computers manipulate binary patterns.
Convert the denary number 184 to 8-bit binary.
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1011 1000
Why: 184 = 128 + 32 + 16 + 8: both nibbles are correct (2).
1011 1001
Why: Converts 185 instead (a slip in adding up the place values). The first nibble is correct (1); the second is not.
0001 1101
Why: The bits are written in reverse, smallest place value first. Neither nibble is correct.
Computer systems manipulate bit patterns.
Convert the denary number 140 to 8-bit binary.
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1000 1100
Why: 140 = 128 + 8 + 4: both nibbles are correct (2).
1000 1101
Why: Converts 141 instead (a slip in adding up the place values). The first nibble is correct (1); the second is not.
0011 0001
Why: The bits are written in reverse, smallest place value first. 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 |
|---|---|---|
| 0011 0100 | Logical shift left by 3 |
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1010 0000
Why: Every bit moves 3 places left, with 0s in from the right: both nibbles are correct (2).
1101 0000
Why: Shifts 2 places instead of 3. The second nibble is correct (1); the first is not.
0000 0110
Why: Shifts the bits the wrong way. Neither nibble is correct.
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