The SCSI protocol relies on DMA calls being correct
:rtfm: The SCSI protocol doesnt require DMA. Some SCSI cards use DMA local bus mastering, some dont. You can even switch bus mastering off on cards that dont work with a certain revision A3640 to make them work!
One of the problems with the 3.0 cards is a DMA local bus mastering problem it is NOT (as previously stated) a SCSI problem.
If your SCSI requires DMA (Like the A3000 internal SCSI) then you are going to require a -02 U209 PAL or higher or switch off DMA. If your card doesnt use DMA, you'll be alright. Simple as that.
As you say a card designed to use DMA will probably be painfully slow without it (depending on CPU power) but hey.
Cut & jump is obviously a "work-around". Do you have a link with reference to the cut & jump procedure?
The Cut n jump fixes a problem with sampling the bus signals (STERM) so your Cybervision will work. The 3.1 -02 PAL fixes the bus mastering issue. The 3.2 -03 PAL fixes the the bus mastering issue in a different way without delays of upto 10 us per DMA access (Fixes GVP PhonePak and increases throughput).
http://wonkity.com/~wblock/a4000hard/a3640ref.htmlThere is a better page somewhere with pictures, I'll try and find it.
This is another good A3640 site. This repair of the capcitors can sometimes resurrect seemingly dead A3640's
http://joj.home.texas.net/amiga.html