GORF U15 (DATA) IC

[RGP]

This might be a long shot but in investigating the spare boardsets for GORF that me and U72 have, at present it looks like everything except our CPU boards are good and when working my way down the parts on the CPU board all I can seem to find wrong is the chip marked as U15.

On the schematic this is called "DATA".

One seems completely dead whereas the other seems to generate garbage and jailbars etc.

If I replace the IC with a known good one all problems go away.

Is it possible to obtain these and program them, not sure what device they are.

Here's a picture of the IC in question:



RGP2013-12-15 17:39:30

 

[trm]

What IC markings are on it? Sounds like a PROM of some kind.

 

[RGP]

Updated first post with a pic, I fear this is one of the custom chips that hasn't been broken / reverse engineered yet.

 

[trm]

Looks like it unfortunately.

 

[bbz149]

That's a Custom that was used on only on Gorf and Wizard of Wor as far as I know and I would say impossible to find a NOS one as they are rare. But just so happens I have a spare I would part with for the right price!

Sure out of U3 and 15, 15 needs a Heat Sink and they started to fit them later on as they quite warm!
bbz1492013-12-15 18:45:42

 

[guddler]

Only just seen this. Yeah, that's the custom alright.

Fancy another project Mr Matthews??

 

[trm]

Hehe. That's just what I need at the mo

Ordy hasn't chased me recently for progress on his R360 code hack and I've not yet quite exhausted my skills hacking R-Type Leo on the plus side, but when you've read my rainbow LED code I suspect I'll have a lot of learning to do!

It's always evil having to show non-professional programmer's code to a pro

 

[trm]

Although I do have to confess I quite like the idea of reversing a custom chip (as long as it's not implementing combinatorial logic). It's a bit like the crypto puzzles I used to enjoy.

 

[RGP]

Tim, i'm putting a bounty on this if needed, we need to get these two done as its the only way to preserve the original game.

Ideally we could do with turning the whole board into FPGA.

Go on Terry, please speak to me, both of these sets came from you originally so if you have any spares we'd really appreciate them.

RGP2013-12-16 00:19:39

 

[trm]

So much going on at the mo. My Dad and I seem to be determining the internal micro-architecture of the 68k and the Sega System16B via bus sniffs alone. And Gudd is your man for conversion into HDL

I'll have a look at the Gorf schems and see what feeds it. I would prefer to extend the lifestyle of VAC over some of my other hobbies, so never say die!

 

[RGP]

Thanks Tim, encouraging as always.

Am I right in thinking (from the manuals) that the U3/U15 chips were the same on Space Zap, Wizard Of War, Gorf etc that used that system? If so, then a scavenge around for some of these boards might help (as well as Terry mentioning he might have a spare U15 to let go).

It seems that a game like this (and it's other brothers of the same card system) haven't been considered by JROK yet for a multigame FPGA implementation as we all know that GORF ownership comes with this particular drawback.

LONG LIVE GORF!

 

[Alpha1]

If it were me, I would make a little replacement board to go in the customs socket.

 

[RGP]

The good news is that U15 is in the middle of the board so quite easy to put a board in but U3 is part hidden under the cage so wouldn't be so easy. We'd need to make something very low profile to do it.

Reversing both at the same time would be the idea thing as they're the 2 IC's you can't get - everything else is generic logic but the RAM's can be a bit pricey now - but again, i'm sure there's a way to re-do the RAM cards into something more modern.

Thinking aloud here, RAMs sit on the address and data bus, it's the /CE line that gets selected by the addressing logic to denote which one is accessed so we'd have to replace the addressing logic as well as the chips.

Someone has done a single-EEPROM mod already.

Hmmm, i'm just wondering if we're not that far off at least making a single board version of this game (cowers from the purists) - single EEPROM, single (or less) RAM, interface board logic has to be kept and CPU board could be squashed once we know what is going on in those two customs.

I'm guessing U3 is literally just a custom address logic chip for the card rack.

So, what's U15's purpose in the game - decryption, nah.

 

[Ordyne]

If it were me, I would make a little replacement board to go in the customs socket.

Go for it oll, waiting to see your progress

!!

 

[guddler]

Is U3 the GAL? If so the source is available for that.

I'd not be interested in any single board solution but a drop in replacement for U15 would be good as a small board. I would imagine it wouldn't be socket science to do either but unfortunately I have way too many projects on the go to even contemplate it, plus there's no way I'm risking my working cab to it !

 

[trm]

Single FPGA replacement for the whole thing is waaaaay too much effort. But as for low-profile, this is chip prob has enough LEs to replace the entire board and ought to fit under a daughter card.

 

[trm]

U15 sits in the middle of the clock circuit doesn't it?

 

[cmonkey]

U15 is a data bus buffer, according to the page below

http://cambridgearcade.dyndns.org/?q=node/77

I'd imagine that U3 does a similar job, but for the address bus.

 

[trm]

Can somebody link me to some high quality Gorf schems? I've not looked at them but if it is a bus driver then it should be pretty obvious.

 

[RGP]

Ask and ye shall receive:

Gorf_Parts_and_Operating_Manual_(Feb_1981).pdf

Very detailed manual and the schemes are great, i've had them printed at A0 size if you want big prints let me know Tim and i'll arrange for you.