26064Re: ROM Bootloader Issues
- Jun 2, 2012Kyle, come to think of it, I think there's a CPX instruction to compare X with immediate, so you can affect the flags.
--- In firstname.lastname@example.org, joshbensadon <no_reply@...> wrote:
> Kyle, oh, I don't think DEX affects the flags...
> --- In email@example.com, Kyle Owen <kylevowen@> wrote:
> > Hi guys,
> > So I recently copied 8k BASIC to (4) 2kB EEPROMs in hopes that I could make
> > a bootloader to copy the contents into RAM, eliminating the 5 minutes or so
> > that it would otherwise take to load BASIC via RS-232.
> > Anyways, I'm completely stumped as to why my very simple bootloader isn't
> > working correctly. The code can be found here: http://pastebin.com/jbrTHdnX
> > It actually does copy the contents correctly, but fails to exit to the
> > monitor on time. The DEX instruction can only update the zero flag, so I am
> > fairly limited on branches. It should exit the loop as soon as the index
> > register is zero, but instead, it exits well after the index register
> > underflows.
> > Any help would be much appreciated, as always. Thanks!
> > Kyle
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