Why?: We can approximate calculations to sacrifice accuracy to save time, speed, and power.
- e.g., search results don’t need to be 100% certain, you don’t need to play every frame of a video.
Approximate Half-Adder
Original
| A |
B |
C |
S |
| 0 |
0 |
0 |
0 |
| 0 |
1 |
0 |
1 |
| 1 |
0 |
0 |
1 |
| 1 |
1 |
1 |
0 |
| A |
B |
C |
S |
| 0 |
0 |
1 |
0 |
| 0 |
1 |
0 |
1 |
| 1 |
0 |
0 |
1 |
| 1 |
1 |
1 |
0 |
Approximate Half-Adder Minus
Original
| A |
B |
C |
S |
| 0 |
0 |
1 |
1 |
| 0 |
1 |
0 |
0 |
| 1 |
0 |
0 |
0 |
| 1 |
1 |
0 |
1 |
| A |
B |
C |
S |
| 0 |
0 |
1 |
1 |
| 0 |
1 |
0 |
0 |
| 1 |
0 |
0 |
0 |
| 1 |
1 |
1 |
1 |
- C = A XNOR B
- S = A XNOR B
Approximate Half-Adder Plus
Original
| A |
B |
C |
S |
| 0 |
0 |
0 |
1 |
| 0 |
1 |
1 |
0 |
| 1 |
0 |
1 |
0 |
| 1 |
1 |
1 |
1 |
| A |
B |
C |
S |
| 0 |
0 |
0 |
1 |
| 0 |
1 |
1 |
0 |
| 1 |
0 |
1 |
0 |
| 1 |
1 |
0 |
1 |
Approximate Half-Adder Minus Minus
Original
| A |
B |
C |
S |
| 0 |
0 |
1 |
0 |
| 0 |
1 |
1 |
1 |
| 1 |
0 |
1 |
1 |
| 1 |
1 |
0 |
0 |
| A |
B |
C |
S |
| 0 |
0 |
0 |
0 |
| 0 |
1 |
1 |
1 |
| 1 |
0 |
1 |
1 |
| 1 |
1 |
0 |
0 |