Re: creating a new Apple IIgs ROM 03 checksum

[barrym95838 <barrym95838@yahoo.com>]

> I do not know if i understand wrap around correctly but what i can say is:
> 
> - if you set the data bank with pea plb plbthen you can use the ($) zp addressing instead of the long one. Useful for saving cycles.
>  
> I am not an orca expert, are long a.m.x etc. sufficient? No need for a REP #$30?
>

It seems to me that if the uninitialized value @ $fd is an odd number, then the 16-bit check-sum is guaranteed to be incorrect.  If it's an even number, then it might be okay due to wrap-around.  I have almost no 65c816 experience, but it seems to me (with all due respect) that Larry's subroutine is a candidate for some revisions and optimizations.  If I'm stepping out of line, I apologize, especially since I would have to do some studying before being able to do any better.

Mike