[Coco] Coco Digest, Vol 166, Issue 29

Arthur Flexser flexser at fiu.edu
Sun Aug 21 19:21:15 EDT 2016

The check at $FFFF should work fine.

I would assume that the program copies ROM to RAM if it needs to store data
in high memory, or at least puts the CoCo in RAM mode.  That should mean
that the poke to $FFDE is unnecessary.  And I think that having a separate
test for the CoCo 3 will also turn out to be unnecessary, now that you've
fixed the problem with the interrupt vectors being overwritten.  That is,
the program shouldn't care if it finds the CoCo 1/2 value or the CoCo 3 one
in $FFFF.


On Sun, Aug 21, 2016 at 7:08 PM, Pere <psergm at gmail.com> wrote:

> Hi Art,
> I am afraid you are right, I cannot asume the installed DOS version despite
> the program
> will only work for dos11, dos12 and dos12a
> I will use the byte at $FFFF because it seems clearly related to the
> machine.
> Just to mention. As the program needs to modify data located at
> $E000-$FEE2,
> it is
> mandatory to work in MAP1 (all RAM) all the time, well this is how it goes
> for Dragon and CoCo2.
> Anyway, after doing the poke &HFFDE,0 on the CoCo3 it seems to work well.
> If it were back to ROM  mode, it could not find the Objects and Locations
> data because
> that space is used by the Super Extended Basic ... and it is working, so it
> seems that
> the CoCo3 does always work on RAM (whatever the selected map is)
> thanks a lot for your unvaluable help!
> cheers
> pere
> ------------------------------------------------------------
> ------------------------------------------------------
> Previous message (by thread): [Coco] The Hobbit ported to 6809 (Dragon64
> and
> coCo2 64k)
> Arthur Flexser flexser at fiu.edu
> Sun Aug 21 18:43:26 EDT 2016
> The check you are doing at $C008-9 will fail if the CoCo has Disk Basic 1.0
> (or a 3rd party modified Disk Basic based on that version, such as ADOS).
> You should check for the 1.0 value (see Disk Basic Unravelled) as well.
> The poke to $FFDE will do no harm on the earlier CoCos, so might as well do
> it unconditionally, unless that will mess up things for the Dragon.
> To check for the CoCo 3 (if you actually need this additional test), try
> this:  Prior to doing the $FFDE poke, look at someplace within the Super
> Extended Basic range to see if the value matches the CoCo 3 one.  You need
> to do this BEFORE going to ROM mode, or the value won't be there.
> There are also places within Color Basic that have values unique to the
> CoCo 3, where the test for a CoCo 3 could be done in ROM mode, like where
> the DLOAD command code used to be on the earlier CoCos.
> (Or, as I see Brett has just suggested, check the interrupt vectors.)
> Art
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco

More information about the Coco mailing list