Computer systems manipulate bit patterns.
Convert the 8-bit binary two's complement pattern 1100 1011 to denary.
Mark scheme
Award one mark for each of:
- − (negative sign) (1)
- 53 (1)
The correct answer is −53
Example answers and how they were marked
Full marks2/2
−53
Why: The left-hand bit is worth −128: −128 + 75 = -53. Sign (1) and value (1).
Some marks1/2
53
Why: The value is right (1) but the minus sign is missing.
No marks0/2
203
Why: Reads it as an unsigned number, so neither the sign nor the value is right.