Sega ST-V gal chip

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
Hi,

Is there any way to read or duplicate the data stored on the gal chip labeled 318-5833? I know this one is a protected device but perhaps somebody has found a way to fix this problem.

Thanks in advance.

Marcelo
 

mainman

CPS2 Person.,
20 Year Member
Joined
Mar 26, 2001
Posts
3,752
I gamble no one has given this hardware that much attention to duplicate the gal data outside the mame team. It would be cheaper and quicker to buy a broke mobo for a sac
 

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
4,275
You sure you have the right diagnosis?

I've seen a LOT of CPU problems on those boards. If the board is flaky then I suggest running factory tests (hold down test and power on) - especially the slave CPU test.

RJ
 

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
Thanks guys for the reply.

mainman, I supposed that :( However it is difficult to get one of these here.

RJ, I am quite sure. I have done a check with a logic probe and all pins are in high impedance.

Any other suggestion?

Marcelo
 

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
4,275
If they aren't protected (security bit set on the chip) then you can read them in many different EPROM programmers.

If they ARE protected then the only thing you can do is send different combinations of signals in to see what the outputs are. From there you can deduce most of the configuration of the GAL.
 

Kyuusaku

B. Jenet's Firstmate
Joined
Mar 26, 2003
Posts
419
Unless of course the GAL is registered or contains synthesized latches. Using PLD for just an address decoder isn't very likely if the circuit also contains ASIC.

The best way to figure it out is to a deep log of it in operation with a logic analyzer + finding purely combinatorial outputs with an Espresso logic minimizer.
 

mainman

CPS2 Person.,
20 Year Member
Joined
Mar 26, 2001
Posts
3,752
Unless of course the GAL is registered or contains synthesized latches. Using PLD for just an address decoder isn't very likely if the circuit also contains ASIC.

The best way to figure it out is to a deep log of it in operation with a logic analyzer + finding purely combinatorial outputs with an Espresso logic minimizer.


Yeah this pain in the ass task is the reason why I only found the truth table for one cps2 gal chip and didn't do the rest.
 
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