Since ages I am trying to get hold of a Roland MPU-IMC card for one of my IBM PS/2 systems.
I collected several other Roland and clone cards over the years but had no luck with the MCA card.
Then I stumbled across the MPU-IMC Clone github project https://github.com/schlae/mpu-imc.

Though there is a clear warning about the two missing chips I thought maybe it is possible to transfer this ICs from one of the other Roland Cards.
The MPU401/AT seems to have the identical QFP IC.

So I went ahead bought an original breakout box from eBay and produced some of the "stock" PCBs.
The producer refused to print "Made in Denial" on the PCB, 🤣.

I took of the Microcontroller (Motorola 68001 + ROM?) and logic chip from a known working card.

Installed the SMD mount chip (most tricky part, I reworked it later)

All ICs get sockets.

The card is almost finished.

Time to test it.

The card gets actually detected by the BIOS and can be configured using the IBM reference disk.
If I hook up the breakout box, the buzzer in the box beeps all the time.
This is similar to a normal MPU-401 if it has a faulty ROM.
If I remove the SRAM or the microcontroller, then it becomes silent.
I also tried different microcontrollers from the original MPU-401 and a CMS-401 clone card. (No buzzing)
But I can't get DOS games to detect the interface.

I had to change the interrupt from 2/9 to 3 because IRQ2/9 is used by the onboard SCSI controller.

Was I silly to believe it could be done that easy?
Any ideas how to rescue this project?

If you are up for experiments I have 2-3 of the PCBs that I can spare.