1.2 KiB
1.2 KiB
Lecture 1 (12:00) - Twos Compliment
- First field becomes -128
- Overflow happens when:
- Both numbers are positive or negative
- Sign is different to sign of input
| -128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 | Output |
|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 10 |
| 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | Invert |
| 1 | 1 | |||||||
| 1 | Overflow | |||||||
| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
-10x10 = -10 x (8+2) = (-10 x 8) + (-10 x 2)
| -128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | <<< |
| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | < |
| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | -80 |
| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | -20 |
| 1 | 1 | Overflow | ||||||
| 1 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | -100 |