Space duel on BW/G hardware (Was RE: reprodutcion artwork...)

At 12:09 PM 7/31/98 -0400, Ed wrote:
[reproduction artwork comments deleted...]
>
> On another note, is there any real difference between the vector
>generators that Space Duel and Gravitar use? I was looking at the
>schematics the other night and really couldn't find anything that stuck
>out like a sore thumb. Has anyone found any major differences between the
>two games hardware wise? Maybe Space Duel really could be banked onto a
>Gravitar/Black Widow setup or vice-versa.
>
>Thanks!
>
>Ed

Ed,
        I've analyzed the Space duel vs Black widow / Gravitar pretty thoroughly.
You can't easily run BW/G on the SD vector board for three reasons: 1.
BW/G use more vector RAM memory. 2. SD does not have the third MDAC (AKA
linear scaling). The MDAC is actually on the SD PCB, but it's not
installed. 3. Inputs are 8 in to 1 bit muxed on Space duel, and 8 bit
latched on BW/G.

However... It does look reasonable to run SD on BW/G hardware. It would
require the following changes: 1. Remove the 2 (or three) chip select
decoding PROMs and replace them with a couple of GAL22V10/16V8s (so you can
"bank switch" the memory maps). 2. Add bigger Eproms to the Vector
generator and CPU sections (ala SW->ESB). 3. modify the SD software to
read inputs as 8 bit latched data rather than 8 to 1 muxed data (ala Clay's
sega control panel). Note: for the first test, #3 is not needed, you just
won't be able to play the game, but is should still run in attract mode.
4. I'm assuming that the SD code will correctly initialize the BW/G scaling
MDAC to the correct value. This is probably a reasonable assumption since
all other color vector games use it, so it should be part of the standard
initialization.

The real messy part of the SD/BW/G multigame is the banked switched memory
map, every thing else has been done before.

Sorry if I've left anything out... My notes are at home, and I am recalling
this from long term (+6mo) memory.

-Scott

--
Scott Swazey                QUALCOMM Incorporated Work: (619) 657-2419
mailto:sswazey@qualcomm.com V-209H                Pager:(619) 683-5210