[Info-vax] DLT drives and antique SCSI compatibility

[Roy Omond]

On 17/07/2020 06:57, Michael Moroney wrote:
> Dave Froble <davef at tsoft-inc.com> writes:
> 
>> It's my guess that some of what DSSI could do might still be useful,
>> but, as mentioned, there might not be the volume to support specialized
>> equipment.
> 
>> Think about it for a bit and one will realize there was all kinds of
>> good ideas in the past.  Including Alpha ....
> 
> DSSI was enough like SCSI that on a certain VAX box part of the configuration
> was telling it whether an IO board should talk DSSI or SCSI.
> 

That would have been the DEC 4000 model 600 (Cobra) and 700 (Fang)
boxes (Alpha, not VAX) if I recall correctly.

https://en.wikipedia.org/wiki/DEC_4000_AXP

The DEC 4000 AXP uses the KFA40 I/O module, which contains the entire 
I/O subsystem. The I/O module is the largest module in the system, and 
two variants existed. The first variant offered four SCSI-2 buses and 
two Ethernet ports and the second variant offered four DSSI/SCSI buses 
and one Ethernet port. The second variant however only has half the 
bandwidth of the SCSI-2 buses of the first variant, although the 
advanced features of DSSI justified its use in some cases. Aside from 
these differences, the rest of the I/O module was essentially the same.