RE: Cinematronics Masked ROM part numbers

In message "RE: Cinematronics Masked ROM part numbers", you write:

>ps - I'd guess you have a Speed Freak, but it could be a Warrior. Could
>you describe the wiring mods.
>
>I forgot to bring in the actual numbers with me to work today (I sent mail
>to Zonn with them, but never heard anything back)
>
>The ROMs sit in the 1st and third slots, with one leg of each lifted and
>run over to the adjacent empty slots.
>
>used <empty> used <empty>
>
>Thinking about it, I think I remember the Speed Freak ROMs being set up
>this way on MrBill's board.

Those are probably Tailgunner II ROMs. Some game boards use 2 PROMs
instead of the normal 4 PROM setup. These 4K masked PROMs were
mistakenly manufatured with the 2K blocks reversed (either that or they
put the ROM sockets in the wrong pair of spots)!!! To fix this, they
lifted the 2K address leg of each PROM so that it didn't go in the
socket and jumpered it to the ROM spot to the left which uses an
inverted signal for that line. This jumper easily comes loose so the
best solution is to pull the PROMs, read them in, swap the 2K blocks and
burn them into a new EPROM and do away with the address hack altogether.

--
THANX...Gregg   day 214.684.7380  night UNLIST/PUBL   TEXAS NOT CANADA!
              woodcock@nortel.com  or  woodcock@dfwmm.net
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