Mike,
My original Thylacine works fine in my A2000 rev. 6.2b. Your system sounds awfully close in horsepower specs to mine. I am running a PP&S A2000/040 @ 33MHz using the Thor MULibs suite. I use a GuruROM equipped a2091 w/14MHz hack and SCSI2SD v6 for my storage. I have a DKB Megachip and Indivision ECS as well. I get a consistent 1.75 MB/sec transfer rate via the SCSI setup. There is a little DMA lag (mouse pointer ratchets while the Poseidon stack is recognizing and reading the directory structure of my memory stick, but once the initial read is complete, works like a champ. Pretty impressive considering the ZII is all I have going for me, as the 040 has no onboard SCSI controller and all the storage access has to traverse the bus.
