(Topic ID: 261245)

Identifying Bally / Stern MPU Boards


By oldschoolbob

58 days ago



Topic Stats

  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 56 days ago by Quench
  • Topic is favorited by 2 Pinsiders

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    #1 58 days ago

    It seems the more I learn the less I know. I haven’t worked on many Bally games but I’m familiar with Stern games. Stern has two boards – MPU 100 and MPU 200. Easiest way for me to identify between them is the 200 has U13.

    Bally has three boards – AS-2518-17 – AS-2518-35 and AS-2518-133. The 133 is an oddball only used in a few games so I’m not too concerned about it.

    All this time I thought the 17 was like the 100 and the 35 was like the 200. I just found out that is not true. About the only difference between the 17 and the 35 is the number of pins on the J5 connector. (32 vs 33). My question is did Bally ever make a board comparable to the Stern MPU 200?

    Thanks

    Bob

    #2 58 days ago
    Quoted from oldschoolbob:

    All this time I thought the 17 was like the 100

    Indeed it is the same.

    Quoted from oldschoolbob:

    and the 35 was like the 200. I just found out that is not true. About the only difference between the 17 and the 35 is the number of pins on the J5 connector. (32 vs 33).

    There is fundamentally a bigger difference between Bally -17 and -35 boards. The -35 boards support double the amount of ROM capacity which was needed when their games became more complex. Lost World was the first -35 game. This was done by using a previously unused CPU address line in the ROM mix. The extra pin at J5 is that address line (A14).

    Quoted from oldschoolbob:

    My question is did Bally ever make a board comparable to the Stern MPU 200?

    Bally never made a board with dual battery backed RAM.
    Other differences are MPU-200 ran a reset signal to the J4 connector pin 13 that ran to the cabinet slam switches allowing them to remove the slam tilt switch from the switch matrix, an interrupt line was run to J4 pin 11 that was used with their speech board.
    Other big difference is the CPU on the MPU-200 boards was run at nearly twice the speed of the Bally-35 board. Stern developed a high level programming language requiring the extra CPU speed.

    Note there was a 4th type of Bally MPU board at the end of the run and used on Fireball Classic and #Cybernaut. The 6800 CPU was replaced with a 6802, it had a socket for 2764 EPROM and the battery backed RAM was higher capacity. See here:
    http://www.pinball4you.ch/okaegi/pro_6802.html

    #3 57 days ago
    Quoted from Quench:

    This was done by using a previously unused CPU address line in the ROM mix. The extra pin at J5 is that address line (A14).

    So would the -35 be backwards compatible to the -17 (and MPU-100)?

    Could I replace all the ICs (including the ROMs) from a -17 into a working -35?

    Looks to me that the MPU-200 is also a bit of an oddball. No other boards are interchangable?

    Thanks

    Bob

    #4 57 days ago
    Quoted from oldschoolbob:

    So would the -35 be backwards compatible to the -17 (and MPU-100)?

    It could be provided you format the ROMs correctly. I've never entertained this downgrade but you would have to program EPROMs accordingly by putting the -17 ROM code into the correct areas of EPROM.
    PinWiki discusses the data structure of the ROMs here though it mostly relates to -35 setup:
    https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Jumper.2FROM_Info

    Quoted from oldschoolbob:

    Could I replace all the ICs (including the ROMs) from a -17 into a working -35?

    Besides the ROMs yes. The type of ROMs will determine if you just need jumper changes or to reprogram replacement EPROMs.

    Quoted from oldschoolbob:

    Looks to me that the MPU-200 is also a bit of an oddball. No other boards are interchangable?

    Other than reproduction boards, no. The MPU-200 is the more powerful of the lot. Double CPU speed. Double battery backed RAM. Double the ROM capacity of a MPU-100 (but same as Bally-35 boards).

    #5 57 days ago

    Note that weebly.com sells kits to let you make the -17 and -35 boards -200 compatible.
    https://nvram.weebly.com/repair--conversion-kits.html

    It probably can work on the stern -100 board as well.

    To stir the pot further, if you use an mpu200 in a game originally using only the one 5101 at u8, you should remove the 5101 at u13. Some of the bally games use code that increments a memory location in the 5101, and when 2 are installed, the increment is wrong.

    #6 56 days ago
    Quoted from Quench:

    Besides the ROMs yes. The type of ROMs will determine if you just need jumper changes or to reprogram replacement EPROMs.

    The reason for such a strange question is my good friend has several games - mostly Stern's and mostly MPU-100's. He's a pinball player and collector - not a pinball repair person. My thought was if he has a MPU problem I could just send him a rebuilt board and he could change out the IC's and be up and running. I just scored a few Bally boards (-17's and -35's). Reprogramming EPROMs and changing jumpers would be out of his ability. I have a couple of MPU-100's and a Bally -17 in case he needs them but was wondering what to do with the -35's I just acquired.

    Quoted from slochar:

    Note that weebly.com sells kits to let you make the -17 and -35 boards -200 compatible.
    https://nvram.weebly.com/repair--conversion-kits.html

    Thanks slochar, I have never seen that kit before. And thanks to Andrew for making it. That looks like a great idea. I have a Meteor game in my shop at present. It works fine but I think I'll get one of those kits and convert one of my -35's just to see how well it works.

    Thanks for the lead.

    Bob

    #7 56 days ago
    Quoted from oldschoolbob:

    My thought was if he has a MPU problem I could just send him a rebuilt board and he could change out the IC's and be up and running.

    But you've fixed all his MPU boards and they're 150% so shouldn't fail right
    Since you're getting an EPROM programmer you could just send him complete MPU boards that will plug'n'play.
    The less he does to the suspect boards (by not removing chips) the better the chance you have of seeing any problem.

    Quoted from oldschoolbob:

    but was wondering what to do with the -35's I just acquired.

    The huge number of Bally-35 games produced should present opportunity to use those boards.

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