Re: 68HC11 Microcontroller

On Thu, 26 Mar 2009, stewartraymond wrote:

> Question:
>
> Accumulator A contains $FF, and the C flag is cleared. If a DECA
> instruction is executed, the Z flag will be ____________________.


Cleared. DECA subtracts 1 from accumulator A and sets the Z flag if the
result is 0, clears it otherwise. ff - 1 is fe, a non-zero value
therefore the Z flag will be cleared. The value of the C flag before the
instruction is irrelevant and the instruction will not change it.


Zoltan