Ensoniq Display/Keypad and/or Emu Emax Keyscan Project

[mateomorikone]

Hello,

I'm currently struggling with broken R1125-11 IM368 Keyscan IC in my E-mu Emax. If there are any resources regarding a viable replacement for the R6500/11 please let me know. I'd love to revive my Emax.

Cheers!

[donnied]

Hi All,

As it seems, according to my post about SQ1, 6500/11 is a culprit. Got another "fully working" board from fleaBay, but alas, half of the keyboard is not working. Didn't break the bank, so, back to square one, but at least I have some spare ESP and OTIS

On SQ1/SQ1/KS32, 6500/11 is used as a key scan, but also feeds Display Out of Pin11 to Display Board.

I have ordered another SQ1 display board of fleaBay to be on the safe side.

If I can contribute to this cause, how do we organise ourselves?

I can see Rasputin and Blueknob have already done some extensive research/reverse engineering and have a head start. Can we look into costs and options? I believe everyone here would be attributing to such research. Also spread the work that this is being done, so we can save many synths from scrappy.

Thoughts anyone?

[donnied]

I stumbled upon this Youtube video of someone reading out Intel 8051 mask ROM.

Any ideas if we can get equivalent for 6500/11 ?

[protosd]

I've been following this thread for several years hoping to see a breakthrough. I have a somewhat decent background with electronics, but not a ton of space or time to delve into this. I have an Ensoniq SD1-32, worked fine last time I hooked it up about a year ago. If I had more confidence/knowledge of the 6500/6502, my approach to read the ROM would be to remove the chip, prototype a basic circuit to run the CPU and write an assembler program that would get the CPU itself to read the ROM and step thru it and write out the contents to the data lines. The ROM may be masked from readers but it seems like you should be able to get the CPU to read its own ROM, copy it to a register, and write that out on the data bus and copy that.

The program would likely be pretty simple just a short loop to read from F400 to FFFF, copy byte to register, write to data bus, increment and repeat.

Ben Eater on youtube has a whole series on the 6502, some of those circuits could be used to do what I describe above. Also there's the something like the HiLetgo USB Logic Analyzer Device on Amazon for $13, you could connect to the databus to capture data and trigger it by the R/W line.

I'd hate to screw up my whole synth by making some stupid mistake and toasting the CPU, but I think this method has some merit. Anyone else with more knowledge think this is worth a go or know why it wouldn't work?

EDIT: After spending time digging thru the datasheet, I understand why my idea above isn't possible. I didn't realize there wasn't access to the address/data lines. I thought they were multiplexed and you could load a short program into the internal RAM.

[meener777]

protosd, unfortunately it looks like the way they did the package the cpu lines are internal only, the pins on the Rockwell 6500/11 package are pretty much power, clock and software defined I/O it looks like. so we dont have access to things like the raw data/address lines from outside and it would require opening up the chip and doing some micro-soldering to directly interact with the ROM. for now the solution to the issue is to head over to buchty.net and grab one of the black-box reverse engineered replacements that he sells. this worked beautifully for me. i now have one of these chips and one day I might try to open the chip up and see if I can pull the data from it, but for now in my experience buchty's replacement works 100% perfectly.

[meener777]

Ha, nm I see you found the info yourself in the datasheet!

[njosnari]

Has there been any advancement with this in regard's to EMU's key scanners? I have an Emulator 3 with a bad R6500-1 that I'm searching for solutions to repair.