RE: Space Wars Demo

I checked and there is a 74LS245 on the VROM databus.
You will have to grab the /we from one of the vrams or pin 11 of J6. One
cool thing this would do is allow a game to use more vram if it wanted to.

I was hoping that maybe there would be some way to extend vector memory
space (non-paged), but the VROMs butt up against program ROMs.

ps. does anybody have a source for 65802's? (pin compatible with the 6502,
but it has 16 bit registers and more instructions).

-jeff
-----Original Message-----
From: Clay Cowgill [mailto:ClayC@diamondmm.com]
Sent: Monday, November 01, 1999 12:31 PM
To: 'vectorlist@lists.cc.utexas.edu'
Subject: RE: Space Wars Demo

> 4) Have a static RAM chip in the daughter card and copy the appropriate
> data
> down when the game is selected. There's a couple ways to do this, but the
> easiest would be for each game to copy the data down during
> initialization.
> This option also might be cool because it would allow shapes to be altered
> in what was previously only static data.
>
I think this is the best way. I don't know Space Duel hardware super-well
though-- is there a 74LS245 or something similar on the VROM databus (so
it's bidirectional). I *think* so 'cause the VRAM is in the same address
decoder range. The menu system would just load the VROM image into the
"shadow" VROM space prior to jumping to the game program code. I also like
that idea 'cause I can stick a 32K*8 SRAM there and we can add a
bank-selection register somewhere in memory. Then, since the VGGO is under
program control we can bank-switch the shadow VROM before every redraw to
achieve something like character-set animation without much of any CPU
use...

-Clay
Received on Mon Nov 1 23:50:04 1999