Sega multi-sound board update

For those not reading RGVAC...

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Subject: Re: Asteroids Multi-Game is Finally Finished!
Date: Wed, 13 Nov 2002 19:11:10 GMT
From: "Clay Cowgill" <cowgill@attbi.com>

Mark Jenison gets credit for pushing me in the "right" direction on
this-- the plan is to add on to the existing *speech* board. (Kinda
clever-- no need to make a new card (less$$$), all the audio signals are
right there, and we need to deal with the voice system anyway.)

The changes are basically a simple bank-switcher on the microcontroller
for the speech (just change out the program/data for that for each game)
and then 1-3 sample playback chips on a little daughtercard that
'vampires' onto the open area of the speech board. Probably be a few
wires to solder. ;-)

I have a few open questions if anyone wants to hack up MAME and answer
them and help out--

    * What's the worst-case (largest) number of simultaneous sounds
triggered in any Sega Vector game
    * What's the "average" number of simlutaneous sounds triggered in
any Sega Vector game
    * Of the largest sound-count, what percentage of time during play
does that occur?

Basically, I have a bunch of OKI 2-channel AD/PCM playback chips which
will be paired up with half megabyte flash memory for sounds. What I'm
thinking it the 'best' solution is to figure out how many voices are
needed on average for Space Fury, Eliminator, and Zektor and then use
(that many/2) sound chips to cover the requirements. The trick is if
(I'm making this up now), say, Zektor uses 5 sounds at once, twice per
game... That might not be worth adding another soundchip and ROM for
that one little case. At any rate, I need to know if the 'peaks' are
closer to 2, 4, 6, etc. My guess is 4 or less. My inclination is to
leave the USB (Universal Sound Board) in the cage and let it do the
sounds for Star Trek and Tac/Scan.

Thanks,
-Clay

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Received on Thu Nov 14 07:46:40 2002