[Coco] Graphics on NitrOS9 Level 1 v3.3.0 (CoCo 1)

[David Ladd]

Rogelio,

So using MAME's debugger I was able to find that where we think it gets
locked up is actually it is stuck in a loop that it never gets out of.
After doing some digging through GrfDrv and VTIO for level1 I did find the
only routine that matched the routine it is forever locked in a loop is in
VTIO

Here is the code
{code}
AddrFind
         bita  #$01       ; Done all shifts ?
         bne   AddrDone
         addb  #$2        ; increment addr offset ptr
         lsra
         bra   AddrFind   ; Test again
AddrDone
{code}

So from what MAME is showing me A register is always 0.  So hopefully
someone more versed in 6809 assembly and the VTIO for level1 could possible
look into this that understands how this routine should be working.


+-----------------------------------------------------------------------+
| David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
| YouTube: http://www.youtube.com/user/PacoOtaktay                      |
| YouTube Gaming Live: https://gaming.youtube.com/user/PacoOtaktay/live |
| Websites: http://dwladd.com     &     http://www.theterrorzone.com    |
| G+:  https://plus.google.com/113262444659438038657                    |
| G+:  https://plus.google.com/+DavidLaddPacoOtaktay                    |
|                                                                       |
| Do you have your CoCo 3 yet?                                          |
+-----------------------------------------------------------------------+


On Mon, Feb 5, 2018 at 10:12 AM, Rogelio Perea <os9dude at gmail.com> wrote:

> On Mon Feb 5 2018, David Ladd wrote:
>
> So after some looking at NitrOS-9 L1 it does seem there is a issue with
> > VTIO and possible GrfDrv as well.
> >
> > So far VTIO does not seem to automatically load GrfDrv as it should.  If
> > you merge GrfDrv in the OS9Boot file on startup so it is in memory then
> > when VTIO tries to call GrfDrv the system locks up.
> >
> > Graphics display codes that start with $15 to $1F are directed to go
> > through GrfDrv.  Which this functionality seems to be currently broken...
> >
>
> Thanks for the reply and the tech insight David, will take care of
> reporting suspected bugs at the Sourceforge page as noted.
>
>
> -- RP
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>