A <- A - (IY+d) - CY
SBC
A,(IY+d)
| b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | $FD |
| 1 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | $9E |
| d | ||||||||
The contents of the Index (register pair IY) Register is added to a two's complement displacement d to point to an address in memory. The contents of this address along with the Carry Flag (C in the F Register) is then subtracted from the contents of the Accumulator and the result is stored in the Accumulator.
| 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 overflow, otherwise it is reset |
| N | is set. |
| C | is set if borrow, otherwise it is reset. |
If the Accumulator contains $22, Index Register IY contains $1000, the Carry Flag is set and memory location $1005 contains $11, then upon the execution of
SBC A,(IY+$05)
the Accumulator contains $10.