Re: creating a new Apple IIgs ROM 03 checksum

[barrym95838 <barrym95838@yahoo.com>]

> 
> Couldn't this magic word be subtracted after all the other summing was
> 
> complete?  SEC, SBC abs-long, and you're done?
> 

Hi, Jerry

I strongly agree that adding it with everything else in the inner loop and subtracting it when done is the more desirable choice, since that strategy is just as compact, and much faster than 32768 php/cpy/bne/plp combos!  I know, we're only talking about a few hundred milliseconds in this particular case, but the benefit of being aware of this is that it can help in other projects, ones that may have much longer loops and/or tight performance constraints.

Of course, if we were coding for a "more modern" processor, some of us might just let it go as is, and let brute power take over.  I don't usually include myself in that group, since I will likely have an 8-bit mentality for life! ;-)

Mike