Yesterday I tried to implement Icky's DMA fix, without success. But I'm wondering if the problem is my build of the fix or if there's a different problem with DMA that I didn't notice before. (Foolishly, I verified that the US detected when I jumpered out IC6, but I didn't actually use it.)
My build of Icky's fix:

- H4-017.jpg (113.65 KiB) Viewed 1127 times

- H4-018.jpg (119.55 KiB) Viewed 1127 times
(Two different connections to FDCS are due to my debugging attempts.)
Is there anything noticeably wrong with this build of the fix? Yes, that is a 74LS04 on top, and I have verified with the logic probe that it's reversing FDCS and feeding that into pin 19 on IC6. When I was pulling FDCS in from the 1.44 GAL port, I seemed to be getting inconsistent behaviour. Occasionally bombs, occasionally scrambled device names on ACSI, occasionally good device names, but never fully working. When I moved over to pulling FDCS directly off IC5, I am consistently getting device names in HDDRIVER, but always three bombs when I run HDDRUTIL.
If this build looks good, I probably have another problem with DMA somewhere, although I have been very careful to get good solders this time.

I figure I'll pull the fix out and jumper over IC6 again and to a better job of testing DMA without IC6, but wanted to see if there's anything glaringly wrong with my build of the fix first.