+---------------------------------------------------------------------------.
Subject: Cinematronics Tailgunner. Solution for replacing roms
From: "Matt Rossiter"
Date: Thu, 2 Dec 2004

+---------------------------------------------------------------------------.
Well, as some of you might vaguely remember - I've been trying to figure out
how to replace the two 8332 masked roms on my tailgunner because one of them
is starting to go out.
 
I finally figured out that you can use 2532 eproms.  You put them in the same
sockets, but pin 21 needs to stay high and not low...
 
So anyway, if it's not posted somewhere already - maybe someone (like Tom
McClintock) should post this solution up on the web because some tailgunners
use a [rom] daughterboard which would probably be impossible to find.  But
you can easily make a substitute with 2532 eproms. 
 
1) create roms by downloading the tailgunner roms from somewhere and
   combining them.

2) Do a 'c:\copy /b tailg.p7 + tailg.r7 p7r7'  and 
        'c:\copy /b tailg.t7 + tailg.u7 t7u7'  (or whatever rom name you like)

3) On some tailgunner boards the 74265 (Dual buffer/inverter) at location J4
is jumpered so that pin 3 is severed and pin 2 is jumpered to the through-hole
of pin 3. This sets your address mode.  You might need to make this modification.
http://rossiters.com/docs/tailgunner-rom-pinouts_files/tailgunner-rom-large.gif

4) Burn your new roms p7r7 and t7u7 onto 2532 or tms2532 eproms and put them
in sockets P7 and T7. 

5) Make sure pin 21 is jumpered so that it's stuck high rather than low. The
easiest thing to do is lift pin 21 up so it doesn't stick into the rom socket
and then just solder a little jumper wire from pin 21 to pin 24.  That way
there's minimal (if any) modification to the cpu board. Once you modify the
EPROM in this way, it can be used on other CCPUs - like Star Castle and Armor
Attack.


This will get Tailgunner working on the newer CCPUs. However, in order to use
the game with a Tailgunner sound board, you must disable (remove) the JMI jumper
near G2. The game will work fine without the sound board plugged in, but it
will go dead if it's plugged in and the JMI jumper is installed.


Just as an FYI, I've noticed that re-used tms2532 chips are not extremely
reliable.  If the above doesn't work - try burning another eprom(s).


Matt

+---------------------------------------------------------------------------.