Re: AVG programming question...

From: Jess Askey <jess_at_magenta.com>
Date: Thu Apr 15 1999 - 15:42:10 EDT

Clay Cowgill wrote:
>
> I'm concerned that either the "dec 0x2002" isn't working (so the loop
> never exits), or maybe that since my loop flag gets set in the ISR, but
> possibly prior to the vector generator actually *finishing* drawing the
> frame, maybe I'm getting a bus contention and "dec 0x2002" isn't able to
> change the VRAM.

Can you try reading 0x2002 right afterwards and see if you get the
correct data.

I think Jeff was having a very similar problem when he tried
'animating' on the
Space Duel hardware. Jeff???????

>
> I don't know if Tempest *has* a VG-busy bit I can read to tell when
> things are done drawing...

You need to read the /VGHalt line to see when the VG is done. This may
be the problem?

jess
Received on Thu Apr 15 14:46:46 1999

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