Re: [stella] 3E + interlace woes

Subject: Re: [stella] 3E + interlace woes
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Fri, 8 Jul 2005 09:28:37 -0400
> The only 3E ROM I have is an early notBoulderDash demo, which uses
> interlaced video. Stella doesn't support interlaced video... What should
> I expect to see if I run an interlaced game in Stella? Currently I'm
> getting a black screen, which can't be right... can it?

The demo doesn't use interlaced video. I think it only does some
form of Andrew's ChronoColour. But either way, what you should see
is a picture like the JPG in the message with the binary, but
with 30Hz flicker.

After looking at the 3E code that you committed to the Stella CVS
I think your problem is that you don't handle RAM writing at all
yet. The poke method only traps the bankswitching hotspots. Since
the demo binary reads all of it's graphics from RAM, you only
get a blank screen.

BTW, you also should handle writes to the 3E RAM that are triggered
by accidental reads to the RAM write ports. That's usefull for
finding problems with indexed addressing modes when they are crossing
a page boundary. Andrew had problems with that in his early demos,
like the one you are using to implement 3E bankswitching.

> Can anyone point me towards one or both of:
> - A ROM that uses interlacing, but not 3E bankswitching, or
> - A ROM that uses 3E, but no interlacing?

Not that is is nessessary for the Boulderdash game, but there
is an interlace demo in the Stella archives at

Ciao, Eckhard Stolberg

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