What exactly does a PAL IC do?

I don't know the specifics.

BUT, when you put the wrong PAL/GAL chip on a CPS-1 board, then the video on the screen displays all BLACK. The game will play--blind--fine. But all you will see is a black screen. When you put the correct PAL/GAL chip back on the board, then the color picture comes back. It does not matter if the picture is scrambled or not.

I saw this the other day when my buddy was messing around with a boot CPS board.
 
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PAL stands for Programmable Array Logic, it's basically a custom programmable TTL (logic) IC. It functions as a security device because it is customizable, and has fuses that can be blow to prevent reading it.
 
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Not all PAL/GAL chips are designed or intended for "protection".
Some are simply efficient, cost-effective means to replace numerous other logic chips.
 
So if I need to replace it do I need one from another Konami board or will a PAL with the same part number work fine?
 
Thanks for the great info. I'll check the part number and pull the datasheet for it.

The datasheet won't help you much. PAL chips are generic parts much like PROMS and they are "blown" with the specifics needed for that application - each one can be EXACTLY the same part number yet be a totally different part.

Unless you are swapping one from an exact board in the same postion they are almost 99.99999999% guaranteed to be different.
 
If this thing is dead you have two options.

You will need a PAL with the same Konmai part# from another pcb or
from Konami's Coin Op division. (I just got a 20 year old custom chip
from Sega...so it is possible Konami may still have some)


Most PAL are fuse protected, but a lot of PALs have logical equivalents that
can be burned to a 16V8.
 
When dealing with PALs you have a variety of types...

PAL - Programmable Array Logic - Fuse links get opened with a blast of current to program them to do what you want.

HAL - Similar to a PAL, but is factory made - masked programmed. No fuses to blow. No fuse maps to read.

GAL - Functionally equivalent to a PAL, but programmed like NVRAM. Can be erased and reused as long as no gates are damaged.

PALCE - Similar to a GAL. Has NVRAM to program and can be erased/reused as long as no gates are damaged.

PEEL - Similar to GAL/PALCE

These chips have a bunch of logic gates in them that can be configured in many many different ways by simply programming them to connect them in the ways you want.

They can be used for address decoding, security, and many many more things. They can be used to replace multiple logic gates to reduce chip counts and can be programmed to replace very hard to find ICs (BTW: I have a few NOS 25LS2519 chips...)

A trick with these chips is that they have security fuses to blow or security bits to program. When these are programmed then the chip will either not read at all or will read random junk. The only way to know for sure is to try to read them. If they do have the bits set or fuses blown then the only way to copy one is to try an feed it all the different input possibilities then see what the outputs are. Once you have all of that then you try to figure out what the programming is that will give you those outputs. DOH!

RJ
 
What game is it?? Sometimes the MAME source has some documentation about the PALs on PCBs...
 
They can be used for address decoding, security, and many many more things. They can be used to replace multiple logic gates to reduce chip counts and

Met a board once that had a PAL in a socket on one board, and on another identical board the socket had an LS139 in it. Thought it was seriously overkill!
 
Met a board once that had a PAL in a socket on one board, and on another identical board the socket had an LS139 in it. Thought it was seriously overkill!

Heh. I guess if you're out of LS139s, and you've got a PAL sitting around... you do what you've gotta do :)
 
I've seen that before. It was in the place of a slapstic IIRC on some old Atari board.
 
Apparently PAL 055996 is for the sound system but isn't it Konami boards that won't boot if the sound system isn't working?
 
Well, the MAME source doesn't provide too much add'l info...

It does seem to confirm that the subject PAL is related to sound: http://maws.mameworld.info/maws/driverinfo/mystwarr.c

Code:
Gaiapolis (Version JAF)
 Program and Data ROM redump
  PCB No: PWB353396A
  CPUs  : 68000, Z80
  OSC   : 18.432MHz, 32.000MHz
  RAM   : MN4464 (x3), HM62256 (x9), 6116 (x3)
  DIPSW : 4 Position (x1)
  PALs  : 055996 (sound), 056469A (cpu)

It looks like (at least) "Monster Maulers" uses the same PAL. The MAME driver for Gaiapolis is consolidated with a number of other games, which must be very similar hardware:
Martial Champion, Metamorphic Force, Monster Maulers, Mystic Warriors, and Violent Storm. Unforunately, it doesn't look like that PAL is dumped/included in the MAME romset.

I couldn't find any manual/schematic for Gaiapolis, but there is one for a couple of the other games with similar hardware (as listed above from the MAME driver). Unfortunately, the schematics included in them appear to be incomplete, in that they lack the sound hardware. However, the other PAL on the PCB (the one associated with the 68000) is used for address decoding. I'd guess that your 055996 PAL is used for address decoding for the sound CPU (Z80). If that's true, and schematics could be found, the schems plus the memory map in MAME could probably be used together to create the logic necessary to enable the proper devices based on the address bus lines...
 
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