<> Ok, here goes.  The only difference between the 3100m76 and the vs2000
<> scsi is 0/zip/nada/zero!  They both use the NCR5380 chip to drive the 
<> SCSI bus and whats on the other side is a vax.  Now the NCR5380 is a 

<I'm not at all a hardware guy but seeing things from the software side.
<I also don't know where SCSI ends and where vax starts, but:

Scsi ends in the chip and the other side of the chip is a bunch of 
registers to control and monitor the SCSI side.

<The 5380 is the same, but the drivers for 2000 and 3100/76 are a little
<bit different since DMA is handled different on both machines.

Well the solution seems to be PIO.  Yes, dma subsystems in vaxen are 
different across more than those two.  DMA is also a seperate system
that is not directly part of the microvax microprocessor.  Unlike PCs
the dma can be implemented differently, whereas PCs all use the same 
8237 or a cloned equivelent chip to perform dma.

Its the intimate hardware knowledge needed to make drivers work that is 
missing.

Allison