Single 2764 eprom on Bally/Stern MPU. Anyone done it?

Lindsey

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Single 2764 eprom on Bally/Stern MPU. Anyone done it?

I'm sure there must be a link out there with instructions on this conversion but I can't seem to find one. I would like to convert a bally/stern MPU to use a single 2764 EPROM. Does anyone have instructions on this conversion?
 
I'm sure there must be a link out there with instructions on this conversion but I can't seem to find one. I would like to convert a bally/stern MPU to use a single 2764 EPROM. Does anyone have instructions on this conversion?


I would assume it could be done with a converter...is there a reason why the 2764? I would guess that you would have to build something similiar to what is required when using a 2716 on the gottlieb system one games
 
I would assume it could be done with a converter...is there a reason why the 2764? I would guess that you would have to build something similiar to what is required when using a 2716 on the gottlieb system one games

I'm actually planning to build a daughter board to plug into the CPU socket that will use a single EPROM. I know the 6802 MPU had a socket for a 2764 but it would be much easier to work with instructions to convert a -17 or -35 to 2764 than dig into the 6802 MPU schematic.
 
I have a vague recollection of the 2764 being able to work with the ball-35 cpu. I believe that Bally provided the proper jumpers for the 2764.

I am also pretty sure that you have to use a 6802, no clock and you can upgrade the 5101 to the 5114
 
I've modded all my -35s and -133s (and System 3/6/7) for single ROMs, but I have neither my notes nor any of the boards handy... notes were on my old work computer, so they may be gone...

It's really just a matter of setting U2 up for 2716/2732 and adding wires for the extra address lines, and modding the address decode... i seem to recall having to utilize an otherwise unused gate to create the chip enable.

The address decode on those boards is *really* sloppy, and chips get 'shadowed' all over the place, so you have to be a little careful with the rom select....
 
Thanks, Mark!

That makes sense. Basically I just wire the 2764 into the 2732 socket and built some logic based on the original enable lines to switch the highest address line (A12) and enable the 2764?
 
I have a vague recollection of the 2764 being able to work with the ball-35 cpu. I believe that Bally provided the proper jumpers for the 2764.

I am also pretty sure that you have to use a 6802, no clock and you can upgrade the 5101 to the 5114

You are correct but you're not thinking of the -35. Bally designed an upgraded version of the -35 using a 6802 CPU, 5114 RAM and a socket for a 2764. It had jumpers to map the 2764 into the 2732 ROM space or into unique address space to double the available ROM space. The -35 has no options for any of that stuff "out of the box". Unfortunately this MPU was produced in limited numbers (in fireball classic and some cybernaut). Bally moved to the 6803 system shortly thereafter.

Both boards have a clock (obviously) but the 6802 uses a crystal rather than the dog's breakfast clock circuit of the -35.

I would like to get my hands on one of these boards if anyone has one for sale :)

Here is some info on the Bally 6802 MPU:
http://www.pinball4you.ch/okaegi/pro_6802.html

And here is some info on doubling the ROM space on the Bally/Stern MPU:
http://www.pinball4you.ch/okaegi/pro_softnine.html
 
You are correct but you're not thinking of the -35. Bally designed an upgraded version of the -35 using a 6802 CPU, 5114 RAM and a socket for a 2764. It had jumpers to map the 2764 into the 2732 ROM space or into unique address space to double the available ROM space. The -35 has no options for any of that stuff "out of the box". Unfortunately this MPU was produced in limited numbers (in fireball classic and some cybernaut). Bally moved to the 6803 system shortly thereafter.

Both boards have a clock (obviously) but the 6802 uses a crystal rather than the dog's breakfast clock circuit of the -35.

I would like to get my hands on one of these boards if anyone has one for sale :)

Here is some info on the Bally 6802 MPU:
http://www.pinball4you.ch/okaegi/pro_6802.html

And here is some info on doubling the ROM space on the Bally/Stern MPU:
http://www.pinball4you.ch/okaegi/pro_softnine.html


That first link is what I believe I was thinking about. Pretty interesting using A12 as the chip enable...I remember taking a class on microprocessors and the 6800 series, but that was quite awhile ago!!

Good luck, keep us posted. I would be interested in seeing the pinout and the logic involved
 
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