Sega Multigame (Finally!)

Finally!

Ready to roll on the Sega Multigame! I took a prototype over to a friend's
house and removed his EPROM card and CPU board and popped the whole thing
into a "real" G-80 system. Works like a charm! Found a couple software
glitches (a visual one and a control one) but have those fixed now.

All "production" parts are verified and the schematic is in OrCAD Capture.
I've outputted the netlist and routed a two-layer board with OrCAD Layout
Plus. I'll double check the netlist against the prototype and send off for
boards probably early next week (or late this week maybe).

So... I'm going to order about 16-20 boards. Now's the time for a real
headcount on this one.

I'll sell the kit to people on this list for $75. That includes the
daughtercard (assembled), instructions, a replacement PROM, and the
associated software (on the daughtercard). I'm going to pay Dave Fish a
royalty on each card to say "thanks" for getting the copy-protection
cracked for us. I'm also keeping a cut on these for my time on the menu
system and all the software patches to make the games play from a universal
control panel.

If you want one (or more than one) please send me a note to: clay@supra.com

I don't want to get too many extras, but I don't want to get too few either.
If you've already sent me a note saying you wanted a board(s) please send
it again-- the first request was just to gauge interest level.

I'll probably sell any spares over in RGVAM for $100 a pop. (For some
reason it seems like my "tech support" level goes up dramatically when
"kits" go to people outside of this group of people... ;-)

Oh, Al-- your's is free for the EPROMs and pulling all the programming info
together. ;-)

------Some specs/techy stuff if you're interested------

The Daughtercard houses a single 27C040 or 27C080 EPROM. (512K or 1024K
bytes of ROM.) I'll ship it with a 27C040 that includes:

Star Trek
Eliminator (plays from Star Trek Control panel)
Space Fury (plays from Star Trek Control panel)
Tac/Scan (plays from Star Trek Control panel)
Zektor (plays from Star Trek Control panel)
Eliminator (2player, unmodified except to remove protection)
Eliminator (4player, unmodified except to remove protection)
Self Test (Runs from inside Star Trek)

The Menu system is invoked by pressing the NMI button. There is a space on
the PCB to add a couple wires that run out to a switch (or other signal)
that you can mount someplace else. (Hacker note: you can take a little PIC
and wire it up to P1 and P2 start buttons and have it assert NMI after
pressing and holding the buttons down for 3 seconds or something.) There's
also a place for wires for a reset switch.

If I get it done in time I'll include a new game. :-) It's just
"Breakout", but might be kinda neat...

I'll post updates to the menu system as any improvements happen. You can
burn your own 27C040's or 27C080's, or I'll burn them for you for a few
bucks and shipping.

If anyone wants it, you can have the source to the menu system too if you
want to roll your own.

(I can make a menu system for the 27C080 that includes all the cracked but
unmodified versions as well-- the 27C080 is just too expensive to buy a
whole bunch of at once for putting on every board...)

The Daughtercard has two latches:

        7 6 5 4 3 2 1 0
Latch0: y y y y [--BANK--]
Latch1: x x x x x x x x

Latch 0 serves as a bank select register for the EPROM. The upper four
bits (yyyy) output an active positive "select" bit that can be used to
control some relays or whatever for choosing a sound card. (0001 = USB,
0010 = Eliminator, 0100 = Space Fury, 1000 = Zektor)

Latch 1 is reserved as a "video expansion" latch. Basically it's an output
port that controls a little video adapter card that provides software
controlled width and height adjustment and screen "rotation" (for
tac/scan). The hardware/software isn't done yet.

Both latches come out to a 20 pin .1" dual header if you want to experiment
with anything. Like...

+ 7 6 5 4 3 2 1 0 =
+ 7 6 5 4 3 2 1 0 =

Top row is latch 0, bottom row is latch 1. = is ground, + is +5Vdc.

That's it for now. E-mail if you want one!

-Clay

Clayton N. Cowgill Engineering Manager
_______________________________________________________________________
/\ Diamond Multimedia Systems, Inc. clay@supra.com
\/ Communications Division http://www.supra.com/
Received on Tue Nov 11 12:12:27 1997