[Coco] nitros9l2 artifact colors?

[Arthur Flexser]

I'm reasonably sure that Basic does not update $FF98 on interrupts.  I
believe the updating of $FF98 must be going on somewhere else, perhaps when
a character is output to the screen.

Some $FF98 mirror bytes in Super Extended Basic that you might set bit 5 of
to see if it solves the problem:

$E033  (32 column text)
$E03C (40 column text)
$E045  (80 column text)
$E071 (HSCREEN 1-2)
$E07A (HSCREEN 3-4)

Art

On Sun, Feb 22, 2015 at 2:05 AM, Willard Goosey <goosey at virgo.sdc.org>
wrote:

> On Sat, Feb 21, 2015 at 10:16:25PM -0500, Arthur Flexser wrote:
> > The artifact color mode is controlled by bit 5 of $FF98.  Pressing F1 at
> > reset sets this bit and puts the CMP colors into the palette registers.
> > Hope that helps.
>
> It did, actually!
> PROCEDURE foo
> a=PEEK($FF98)
> a=LAND(a,$F7)
> PRINT a
> a=LOR(a,$20)
> PRINT a
> POKE $FF98,a
> END
>
> This did invert the artifact colors! (The and $F7 is to clear the
> 50herz bit which seemed to be set?) Or anyway it made the text screen
> turn purple, which is what happens when I hit the RESET switch with F1
> down.
>
> Unfortunately, when I started CITY, it reset the colors again, so I
> still had a red sky. :-(  Apparently the game insists. Or covdg resets
> the colors when a graphics mode is selected?
>
> The Disk BASIC version of the program didn't do anything, obviously
> BASIC maintains a byte somewhere with what it thinks FF98 should be
> and updates it on an interrupt cycle.
>
> Willard
> --
> Willard Goosey  goosey at sdc.org
> Socorro, New Mexico, USA
> I search my heart and find Cimmeria, land of Darkness and the Night.
>   -- R.E. Howard
>
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