Re: creating a new Apple IIgs ROM 03 checksum

[barrym95838 <barrym95838@yahoo.com>]

On Wednesday, April 24, 2013 10:01:18 PM UTC-7, Antoine Vignau wrote:
> [...]
> Here, this is a program that is executed in RAM after booting, with an OS installed. You just do not have the guarantee that ZP values are 0.
> 

Hi, Antoine

I'm sure that Larry understands.  I haven't compared my cycle counts with your $0000,x example, but what do you think about something like this?  I always seem to favor shorter over faster when I compose, but I think my way shouldn't be much slower ...

        [...]
        lda  #0
        tax
        clc
ckloop  adc  $fd0000,x
        adc  $fe0000,x
        adc  $ff0000,x
        inx
        inx
        bne  ckloop
        [...]

Mike