sub/sbc

The sub and sub with carry instructions perform the subtractions as shown in the table below. All flags are updated accordingly.

Instruction	Encoding	Semantics	Cycles
sub acc, reg8	01 000 rrr	$\mathit{acc} \gets \mathit{acc} - \mathit{reg8}$	3/41/52
sbc acc, reg8	01 001 rrr	$\mathit{acc} \gets \mathit{acc} - \mathit{reg8} - \mathit{CF}$	3/41/52
sub acc, imm8	00 000 011 imm8	$\mathit{acc} \gets \mathit{acc} - \mathit{imm8}$	3
sbc acc, imm8	00 001 011 imm8	$\mathit{acc} \gets \mathit{acc} - \mathit{imm8} - \mathit{CF}$	3
sub ab, reg16	11 10 00 ww	$\mathit{ab} \gets \mathit{ab} - \mathit{reg16}$	7

1. 4 cycles for unprefixed sub acc, [pi]/sbc acc, [pi]
2. 5 cycles for sub acc, [pi]/sbc acc, [pi] with prefix_a16 (the sequence prefix_a16; sub acc, [pi] takes 6 cycles)