Probably not the best thread to discuss this, but in a nutshell, I'm not sure. I spoke with TubeTime before building this card about 3 months back, and he indicated that he moved to his own FPGA design because he was unable to source reliable P82C611's. However, I have found a reliable supplier for them, and have used 30 in a row from these guys with 100% success so far. He also never mentioned the timing issues to me, so I suspect the timing problems may be with the FPGA implementation. I'm certain getting the timing correct would be tricky.
The Chips P82C611 is a microchannel non-DMA controller which does the decoding of the MCA bus to essentially light up ISA-like signals you can use for your HW. You perform address decoding, in a traditional fashion but all timing signals are generated from this IC. I have several third party cards which use this IC or the DMA version of the P82C612 and I would imagine this would be a pretty widely known issue.
Check page 4 of the P82C611 datasheet, and you'll see how the MCA bus is decoded, http://ps-2.kev009.com/ohlandl/Unsorted_Files … C611-82C612.pdf
If your card is using MME, 32-bit or uses DMA it is up to the device to maintain bus timing. I did not read too much further into it as I don't really plan anything greater than a 16 bit card for the PS/2 at this point. However, it's clear if you read into microchannel a bit, it is almost not compatible with itself at times. 😀
Suffice it to say too, I'm in the market for a 32-bit memory card and I will test this asap. For now, it works great in a 32-bit slot in a Model 70, and in a Model 50Z too. Those are my only two functional machines. I have a model 90, but I think the processor board is dead, but I plan to resurrect it asap as well.