Midway single ROM mod

scottz29

Member

Donor 2024
Joined
Sep 1, 2006
Messages
732
Reaction score
21
Location
Macomb, Michigan
Does anybody have instructions on how to do the single ROM mod on a Midway card stack game (i.e. gorf)?

I have ROM burning capability, but just wondering if it's as simple as only constructing the special ROM, or if board modifications are necessary as well.

Thanks,
Scott
 
Hmmm...

I'd have to sit down and figure out the OE* logic for activating it at the right time... Here's the memory map from the astrocde.c file in MAME:

ROM_START( gorf )
ROM_REGION( 0x10000, "maincpu", 0 )
ROM_LOAD( "gorf-a.bin", 0x0000, 0x1000, CRC(5b348321) SHA1(76e2e3ad1a66755f1a369167fdb157690fd44a52) )
ROM_LOAD( "gorf-b.bin", 0x1000, 0x1000, CRC(62d6de77) SHA1(2601faf12d0ab4972c5535ffd722b03ecd8c097c) )
ROM_LOAD( "gorf-c.bin", 0x2000, 0x1000, CRC(1d3bc9c9) SHA1(0b363a71d7585a4828e08668ebb2999c55e02721) )
ROM_LOAD( "gorf-d.bin", 0x3000, 0x1000, CRC(70046e56) SHA1(392214cc6ed4155bfe022d36f0f86c2594a5ab57) )
ROM_LOAD( "gorf-e.bin", 0x8000, 0x1000, CRC(2d456eb5) SHA1(720fb8b48e20c1fc281d8804259016c3c5364a07) )
ROM_LOAD( "gorf-f.bin", 0x9000, 0x1000, CRC(f7e4e155) SHA1(9c9d6d3bfee6556dc7a01de81d6148dd02f04fc9) )
ROM_LOAD( "gorf-g.bin", 0xa000, 0x1000, CRC(4e2bd9b9) SHA1(9edccceea5af015275582553ed238c40c73d8f4f) )
ROM_LOAD( "gorf-h.bin", 0xb000, 0x1000, CRC(fe7b863d) SHA1(5aa8d824814ee1c30eaf0044da78d3aa8220dcaa) )
ROM_END

Two ways to do this: Put it all one after the other in a 27256 EPROM or space it out across the 64K space of a 27512 according to the memory map from MAME.

After that, decode the address bus where it would activate the OE* line at the right time... keep the CS* line low... and it should work.

I'll have to sit down and see what makes sense for decoding the address lines. I've never programmed my own PAL or GAL chip but that would probably make it a much cleaner mod.

RJ
 
I answered his question.

I've posted about how to do it in the past. If he's too lazy to google for my old posting, why should I help any more?

It's pretty rare to see a question on this forum that hasn't been answered at some point in the past. If this is how it's going to be we might as well just shut this thing down and redirect the link to google.
 
It's pretty rare to see a question on this forum that hasn't been answered at some point in the past. If this is how it's going to be we might as well just shut this thing down and redirect the link to google.

Q: What's the difference between me googling my old post to spoonfeed the information vs. him googling to find it himself?

A: A giant waste of my time.
 
Q: What's the difference between me googling my old post to spoonfeed the information vs. him googling to find it himself?

A: A giant waste of my time.

How about a hint of key words?

I've searched "gorf" "single rom" and have found nothing. I *have* found Tempest and Battle Zone single ROM hacks.

I had to put the quotes around "gorf" to keep Google from returning golf links.

And I tried searching both Google and Yahoo for those key words. I'm wondering if it's really even out on the web... hence my question.
 
The basics are the same for most single rom hacks.
The high level is

1. Concatinate the roms into one file
2. Burn it to an eprom that fits all the data
3. Put the eprom in one of the sockets
4. Attach the pins hanging off to address lines and power somewhere on the board
5. Attach the /OE and /CE pins to the address decoder (usually a 74ls138 or 74ls139)

If you can't find the link it should not be hard to repro
 
If he's too lazy to google for my old posting, why should I help any more?
Chrissakes Mark, I know better than to post here without Googling first. Not too lazy, just couldn't find it I guess. Found lots of posts of you offering the service of doing it, but nothing on "how to". Sorry for wasting your time. However, looks like Channelmaniac couldn't find it either.

It's pretty rare to see a question on this forum that hasn't been answered at some point in the past.
You're right...which is why I was hesitant to post in the first place. Not interested in shitstorms or wasting people's time, just wanted an answer to a simple question that I couldn't find the answer to. Sorry if I'm putting anyone out for a simple inquiry.
 
Last edited:
Zombie thread rises:

https://web.archive.org/web/20170630192755/http://cambridgearcade.dyndns.org/?q=node/77

Took about 15 minutes of high-level Google-Fu.

Damn, I had to look this word up in the dictionary ... :)

ameliorate


[ uh-meel-yuh-reyt, uh-mee-lee-uh- ]
/ əˈmil yəˌreɪt, əˈmi li ə- /


verb (used with or without object), a·mel·io·rat·ed,a·mel·io·rat·ing.

to make or become better, more bearable, or more satisfactory; improve: strategies to ameliorate negative effects on the environment.
 
Back
Top Bottom