Computer systems manipulate bit patterns.
Convert the denary number -48 to 8-bit binary using two's complement.
Mark scheme
Award one mark for each correct nibble in the correct order:
- 1101 (1)
- 0000 (1)
0 marks if the response is not 8-bit binary.
Example answers and how they were marked
Full marks2/2
1101 0000
Why: 48 is 00110000; flip the bits (11001111) and add 1: both nibbles are correct (2).
Some marks1/2
1011 0000
Why: Uses sign and magnitude (a 1 in front of 48) instead of two's complement. The second nibble is correct (1); the first is not.
No marks0/2
1100 1111
Why: Flips the bits of 48 but doesn't add 1. Neither nibble is correct.