A <- 0 - A
NEG
None
| b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | $ED |
| 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | $44 |
The contents of the Accumulator are negated (two's complement). This method is the same as subtracting the contents of the Accumulator from zero.
NOTE:The $80 address remains unchanged.
| S | is set if result is negative, otherwise it is reset. |
| Z | is set if result is 0, otherwise it is reset. |
| H | is set if borrow from bit 4, otherwise it is reset. |
| P/V | is set if Accumulator was $80 before operation, otherwise it is reset. |
| N | is set. |
| C | is set if Accumulator was not $00 before operation, otherwise it is reset. |
If the Accumulator contains 1001 1000, then upon the execution of
NEG
the Accumulator contains 0110 1000.