Error Detection and Correction
To
detect errors, we add extra code to other binary numbers, letters and pictures
We
want to catch as many errors as possible, but not at the cost of adding
too many extra digits
Parity Bits – a bit that records 1 if the number has more 1s, 0 if the number doesn't. Used to check if there is an error
| 0 | 0 | 1 | 0 | 1 |
Check Block – a bit is added to each row and column to show if it is even or odd (yellow) the corner bit shows if the row and column are even and odd (green) If one error, it allows you to detect and correct the error. If two or three, you can detect it. You can detect many errors if there are four errors, but not all.
| 0 | 0 | 1 | 0 | 1 |
| 1 | 0 | 1 | 1 | 1 |
| 0 | 1 | 1 | 0 | 0 |
| 0 | 0 | 0 | 1 | 1 |
| 0 | 1 | 1 | 0 | 1 |