John Payson wrote:

> ; To add a byte to a 3-byte number:
>         movf    source,w
>         addwf   dest0,f
>         rlf     kz,w    ; KZ == known zero
>         addwf   dest1,f
>         rlf     kz,w
>         addwf   dest2,f

Excellent ! :-)

> ; To add two bytes together, with valid carry-in (if source is 255,
> then carry-out will be wrong)
>         rlf     kz,w
>         addwf   source,w
>         addwf   dest,f

        rlf     kz,w
        addwf   source,w
        skpc
        addwf   dest,f          ;and carry-out will be correct too


> ; To add 1-254 to dest, with valid carry-in and carry-out
>         rlf     kz,w
>         addlw   (the number)
>         addwf   dest,f

John. Please explain what you mean 1-254 ? I'm lost in suggestions.

WBR Dmitry.