Trying to understand Bally E-series EPROM logic

[ramegoom]

This post is a bit long-winded, but I hope to strike some interest from the experts out there that were part of the 80's slot designs.

I have several E2000 machines I'm renovating, and have collected dozens of EPROM images from the M1, M2, M3, P1 and P2 chips from surplus CPU boards. I understand the P chips somewhat; they determine the payback odds based on the last two digits of the part number. I plan on using the EPROM images from a set of P chips that pay back 90% - these machines are for home use and I wish to keep the operator interested in playing...

But the M chips. I am not completely understanding them. My question; do they always correspond to the win symbols on the strips? Or is it the P chips that match to the symbols and their locations?

Is there any way to correlate the checksums of the P chips to their corresponding Bally part numbers? Many of the P chips I have accumulated don't have the ID labels on them.

I am assuming the M chips deal with the machine coin-in logic and the number of lines. Am I on track with this?

So, if I find the ideal high-payback-percentage P chips, must they also correspond to that set of M chips or can I swap and test other chipsets? I am figuring on changing the strips on all of the machines to the matching hi-percentage chips to make every machine work the same. Far as I can tell, it's just a matter of matching the EPROMs to the strips and then any E series machine will work the same (ignoring the payout glass and reel glass printing).

Anyway, I'm trying to get these machines to pay nicely, for the man-cave crowd, and further customize the games. Any detailed information is welcome. Hopefully, one of you former Bally employees has some intimate knowledge on the programming of these machines.

Thanks for listening.

[dhellis]

The M1- M3 chips are the basic operating system and the differences are that E1000 machines use Ver. 5.64, E2000 Ver 5.65 and the Military models use Ver 5.71.

I have not been able to find any correlation between part number and checksum but there has to be a way to make this determination because you can read the chip
number by executing test #6

[ramegoom]

That would solve a big mystery, finding the part number, and more, the payback odds for that chip. I have dozens of these from surplus boards, and have logged them by their checksum. If I can match them to a part number, it'd be a good addition to your database on the other site? I'm sure the images would be useful for someone - eventually.

[dhellis]

That would solve a big mystery, finding the part number, and more, the payback odds for that chip. I have dozens of these from surplus boards, and have logged them by their checksum. If I can match them to a part number, it'd be a good addition to your database on the other site? I'm sure the images would be useful for someone - eventually.

The database at http://www.coinslots.com/roms.php has the payouts listed for the game chips that are listed but I guess I need to put adding the checksums on my to-do list since that information was not readily available when I putting all of the information in place.

[ramegoom]

I wonder if the 6 digit part number on the P1 chip is embedded in the binary data of that chip? If it is, it'd be an easy way to ID the chip. If not, would I need to plug it into a functional MPU board and run the test sequence? Haven't tried that yet. Does that test No. 6 display the part number?

[dhellis]

I wonder if the 6 digit part number on the P1 chip is embedded in the binary data of that chip? If it is, it'd be an easy way to ID the chip. If not, would I need to plug it into a functional MPU board and run the test sequence? Haven't tried that yet. Does that test No. 6 display the part number?

I have loaded one of the chips and if the number is there it isn't something that translates to binary so would think that it is encoded, possible using XOR or something similar. You can stick the prom chip into the board and run test 6 and it will tell you what the game chip number is.

[ramegoom]

I'm gonna try that with some of the chips I have. What about the P2? Some of these boards had both P1 and P2 installed. Do they work as a set, or can you run a board with only the P1 installed? I assume the P2 is an extension to the P1 data and they must work together. I have several P2 chips as well, but don't know what their P1 counterpart would be.

I'll start the hacking and hopefully wind up with a reasonable database.

[dhellis]

I'm gonna try that with some of the chips I have. What about the P2? Some of these boards had both P1 and P2 installed. Do they work as a set, or can you run a board with only the P1 installed? I assume the P2 is an extension to the P1 data and they must work together. I have several P2 chips as well, but don't know what their P1 counterpart would be.

I'll start the hacking and hopefully wind up with a reasonable database.

I don't know about how one can find the number of the P2 chips, some games need them while others do not. The only thing that I am sure
of is that the P1 chip is a 2716 and the P2 a 2732