RE: Sega XY - free play

> How hard would it be to modify the code for Tac/Scan, Space Fury,
> Zektor and
> Star Trek such that you could make "home version" of the EPROMs which
> always
> had 2 credits no matter what you did? I think it would be as simple
> as
> initializing the credits to 2 instead of 0, and skipping the decrement
> credits
> part of the code. Of course, self test would need to be modified to
> recognize
> this, and we could put a nice little "H" in the lower left of the
> initial
> screen which indicates ROM version during test mode. :-)
>
That's actually not too hard. Once upon a time I knew exactly where it
was in the code from doing the Sega Multigame boards. I was going to
check into this a while back, but realized that I gave the Mac (that had
everything on it) to a friend of mine... I got the code back from him a
few weeks ago though, so supposedly I have everything again. I just
hope my hacked-up disassemblies made it back on the CDR he burned for
me... Which do you think is better-- always having two credits, or some
"magic" button combo that adds a credit while in demo mode?

If memory serves, the coin routines are actually in one of the main
interrupt service routines-- so they should be pretty easy to find
again. (I guess they wanted 'em in ISR so that you'd get credits even
while the game is playing without having to poll the inputs.) The
timing stuff to defeat flicking the coin switch is in there too.

> Eliminator 4-player is a different story, since the game needs to know
> which
> SIDE wants to play, so modifying that would mean you would have to
> modify the
> "credit timing" switch just so it would be easier to credit.
>
> So anybody out there willing to take on this project? I could offer a
> "prize"
> of some sort for the person who accomplishes this.
>
The Eliminator one could be a little harder, but the "free play" change
for the rest should be relatively straight-forward. I might need to go
find a Mac made in the late 90's and take a look again... ;-) (My
7100/80 at work is a little, shall we say, slow-- for the Emulator.)

-Clay
Received on Tue Feb 16 11:08:15 1999