Disclaimer: This information is provided as is. There may be errors in this information. You may use this information only if you agree that Minimalist / Coinop.org, its employees, and noted authors will never be held responsible for any damage, injury, death, mayhem, etc. caused by errors in the information. When working with high voltage, never work alone and always follow safety precautions.

Document Title: [Space Invaders ROM Hack.html (html file)]

Space Invaders ROM Hack



From: Brendan Keith (brendan.keith@wilcom.com)
Subject: Re: 8080 Midway Board Question

Brendan Keith wrote:
> > On Tue, 29 Jun 1999 08:54:22 -0700, Matt Rossiter <matt@rossiters.com>
> > wrote:
> >
> > >When you re-strap the board, on boards such as Space Invaders, to use
> > >2716 Eproms instead of the 9316.Do you have to use the TMS2716
> > >Eproms or the normal 2716s?
> Another fun way is to burn all 4 or 5 images into a 27128 or larger
> and simply add 4 leads or so to the address jumpers.No cuts needed.
> I can post details later if anyone is interested.
Due to the underwhelming response, I'm going to post the details anyway.
I started with a Bally Space Invaders board.
S6 ROM jumpers were set to AD11->a, AD12->b, AD14->c
I then took a 27256 and burned in both the Space Invaders set and
Space Invaders Deluxe.I can do this because I own both boards so
don't anyone try to get smart.
The ROM set has to be merged and burned in with the H ROM lowest and
the higher segments filled with whatever to make up 2 full 16K
This new ROM can be plugged in to any of the ROM sockets but sockets 
F and G are closest to the jumpers that we need to connect to.
Plug it in with bottom pins lined up. The top 4 pins hang out.
Now for the jumpers.They're really quite simple.
I used a 28 pin socket, bent out the following pins and
soldered wire wrap wire to the legs.The socket itself can then
be plugged in to the existing ROM sockets.
Pin 1 to GND
Pin 2 to AD12->b jumper.
Pin 20 to GND
Pin 22 to GND
Pin 23 to AD11->a jumper
Pin 24 to AD14->c jumper
Pin 27 to the center pole of a switch between GND and +5 to switch
Pin 28 to +5
BTW, I've heard that you can run regular SI on a Deluxe board
but not Deluxe on a regular.  Something to do with some hardwired
code on the sound board.
  I used a Deluxe board so the dual game
worked for me.  You can make a single game version by just using
a 27128 and ignoring pin 27.  Ground it, tie it high, I don't
remember what it does.  You can even fit regular SI into a 2764.
You'll still need those jumpers at pins 2, 23 and 24.  Only two of
them on a 2764.
Brendan Keith