GDROM Bootleg Board?

[twistedsymphony]

https://www.ebay.com/itm/Treasure-I...Sw1Etfe-ff&LH_Auction=1&LH_ItemCondition=3000

I saw this interesting listing and I've never seen one of these before. it seems like a GDROM ODE programmed for a single game.

for future reference the only details were in the title "Treasure Ikaruga Arcade Game Board CN VER PCB Tested Working DVD-154" sold by everyone's favorite Chinese reseller.

 

[Derick2k]

Nice, with keychip and all, pretty need. Is the boot process the same as with a gdrom unit or faster?

I wonder if you could flash other games to it?

 

[Mrhide]

I wonder if you could flash other all games to it?

fixed that.

 

[twistedsymphony]

I would venture a guess that the game is stored on U3 and maybe can expand to the unpopulated chip on the back.

It would probably be no better or worse than CF booting or netbooting, since this would still need to load in over the GDROM interface into memory on the DIMM board.

 

[Derick2k]

I would venture a guess that the game is stored on U3 and maybe can expand to the unpopulated chip on the back.

It would probably be no better or worse than CF booting or netbooting, since this would still need to load in over the GDROM interface into memory on the DIMM board.

Oh missed the unpopulated spot on the back.

 

[Evan]

This is actually kinda cool, probably was made when the Naomi was relevant in arcades.

 

[TheDeath]

Bought from same seller Guilty Gear A core. Pulled out U3 and tryed to read it but there's no silkscreen on it and i wasn't able to figure out the chip type/size. The automatic detection on my programmers suck and they did not help at all. There's also JTAG on it.
It is STUPIDLY slower, it takes 7 minutes to load the game and the process is done twice (no idea why) before the game boots.
The key is a 16F with zerokey code on it

 

[twistedsymphony]

there's no silkscreen on it and i wasn't able to figure out the chip type/size

typical of bootleg boards, they don't want their "competition" to know their secret sauce.

Did GGAC use only 1 chip also? that's one of the larger games on the platform so that chip would have to store a huge amount of data. How many pins is it? Given the data size and pin count that might provide some insight into what chip it is I have a suspicion that it's a serial EPROM, it looks like too few pins to be that large of a Parallel ROM. you should be able to identify power and ground pins and unused pins which might help narrow down the chip model.

It is STUPIDLY slower, it takes 7 minutes to load the game

This leads credence to the Serial EPROM hypothesis.

The key is a 16F with zerokey code on it

That's expected, this is the kind of bootleg that's sent to ops who just want to plug it in and have a new game, using decrypted ROMs with a zero key means they just just make a whole bunch of zero keys and not worry about burning them unique for each game.

 

[TheDeath]

Yeah, i was thinking the same since to my recall i wasn't able to find such big flash roms (it's a tsop4
There's ground in the middle (i don't recall wich pin exactly, but it's in the middle range)
I think one of those 2 asics filled with JTAG/quartus? Maybe altera's? I have no idea without marks on it, but i agree it's not the tsop. I think the bigger one is 29GL064 by Spansion (64MB) but i'm not sure, i've never used bigger flash like these. it's a bit confusing without marks on it

 

[twistedsymphony]

based on the pin count the most it could theoretically be as 512Mbit, beyond that there isn't enough pins for more address lines unless you were doing stuff like dropping down to a single ground pin, or removing CE or something weird like that. I'm not even sure if they make Parallel ROMs that big.
Even still, I don't think that's big enough to fit GGAC on a single chip.

Once you 're in that size most of them are stuff like this: https://www.digchip.com/datasheets/parts/datasheet/456/NAND01GW3B2AN6E-pdf.php

so it looks like they have up to 8Gbit in the TSOP48 Serial ROM. Once you go serial you're no longer limited to pincount either.

 

[MetalliC]

I'd bet the ROM chip is some kind of NAND, which typically have not that much pins.

curious to see its dump, mainly to check out how they "cut the middle area" of (virtual) GD disk.
ISO file system should be located at very beginning of HD area, at LBA 45000, while actual data should be at very end of disk, and DIMM firmware does check that and will not boot the game otherwise.
e.g. developers of bootlegs should use full ~1GB image, or somehow cut/compress unused middle area to save on ROM space.

 

[TheDeath]

The only thing i was able to read on it was the maker, ST, i reconized the logo also by using a digital scope.
Ground is on both middle ends, you can clearly see going to the bigger pads

 

[mathieulh]

The only thing i was able to read on it was the maker, ST, i reconized the logo also by using a digital scope.
Ground is on both middle ends, you can clearly see going to the bigger pads

This is a TSOP 48, try looking for something from ST that matches this format (probably a needle in the haystack though, but I would assume their pinouts/protocol matches on most their TSOP48 NAND ICs).