Figuring out CPS board EPROM types

[channelmaniac]

OK...

After working on a few CPS1 games I figure it's time to start posting info...

The CPS1 games take different types of EPROMs depending on the B board type and the jumper settings.

For 32pin 1Mb EPROMS:

If the silkscreen says 27C301 then it takes NON-JEDEC type 1Mb EPROMs.

If the silkscreen says 1M ROM then it could take either and if it says 27C1001 then it takes the JEDEC type 1Mb EPROMs (27C1001, 27C010, etc...)

For the 40 pin EPROMS/Mask ROMs:

Look at the silk screen... if it says 27C4096 then it's the JECEC style pinout. 27C4002, 27C4095, etc. will work.

If it says HN62404 then it is a totally different pinout. 27C400 EPROMs are what you need to replace these. (NOT 27C040 which are only 32pin 8 bit EPROMs)

Let's look at board jumpers on board 89624B.

Now you might have noticed some solder jumpers down towards the 7F and 8F board area. These jumpers (JP0 - JP1 and DJ0 - DJ1) allow you to change the EPROMs in sockets 28 - 31 and 33 - 36 from the JEDEC to non-JEDEC pinouts.

If the jumpers are set like this, then it is set up for a JEDEC style pinout EPROM.

PJ0
1  4
\xx/
x\/x

And if they are set like this, then it is set up for non JEDEC style EPROMs

PJ0
1  4
x/\x
/xx\

DJ0 controls 28/33
DJ1 controls 29/34
PJ0 controls 30/35
PJ1 controls 31/36

VJ0 and VJ1 do the same thing for the Voice ROMs.

VJ0 controls 18
VJ1 controls 19

I haven't examined the jumpers at LJ3, LJ4, RJ3, or RJ4. They appear to control the A16 and OE* signals for the ROMs at 1-8, 10-17, and 20-27 but I haven't needed to pin them out yet.

Enjoy!

RJ

 

[channelmaniac]

There is another way to set the jumpers as well on the 89624B B board.

If the jumpers are set like this, then it is set up for a JEDEC style pinout EPROM.

PJ0
1  4
|xx|
|xx|

And if they are set like this, then it is set up for non JEDEC style EPROMs

PJ0
1  4
x||x
x||x

 

[werejag]

cool info