[Coco] Programming help

[Luis Antoniosi (CoCoDemus)]

found it on Hot Coco September 1985. Bill you didn't type all the code, it
goes up to line 750. And you need to following basic code to load the asm
and run it.


On Tue, Jun 25, 2013 at 10:03 AM, Johann Klasek <johann+coco at klasek.at>wrote:

> On Tue, Jun 25, 2013 at 11:25:31PM +1000, Mark McDougall wrote:
> > On 25/06/2013 11:13 PM, Bill wrote:
> >
> > >I?m trying to write an assembly language routine, and having what?s
> > >probably
> > >a very simple problem.
> >
> > >70          ORG   $0EOO
> > >80          ORCC #$50
> > >90          LDX   #$8000
> > >100         LDY   #$FFC0      *BANK 0
> > >110   COPY  STB   $FFDE
> > >120         LDB   O,Y
> > >130         LDA   O,X
> > >140         LDB   $08,Y *BANK 00/00
> > >150         STB   $FFDF
> >
> > It's been a long time since I did any 6809 assembler, but at first glance
> > this looks like it doesn't do anything useful; switches in roms, reads 3
> > bytes, switches out roms, then continues to execute whatever's in memory
> > after line 150!?!
>
> Indeed, the loop construction is missing at all.
> No address increments, no counter, cleaning up the interrupt masking
> (ANDCC #$AF) and return to a caller ...
>
> I would guess that $FFDE and $FFDF takes the address of the bank which
> is written to or read from? But this is too speculative to come along
> with a corrected code snippet ...
>
> Johann
>
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> The dragon on my side: http://klasek.at/hc/dragon/
>
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