[Info-vax] DLT drives and antique SCSI compatibility (was: Re: Next release of OpenVMS x86_)

[Terry Kennedy]

On Monday, July 13, 2020 at 3:17:56 PM UTC-4, Stephen Hoffman wrote:
> On 2020-07-12 08:35:34 +0000, Terry Kennedy said:
> > Note that I said rqZx1, not rqDx1. The companion board to the 11/93 CPU.
> 
> Ah; sorry; don't recall ever meeting an RQZX1.
> Don't recall seeing that widget on MicroVMS/VMS/OpenVMS.
> My preferred SCSI nemesis from that era was the KZQSA.

It was a pretty rare board, both because it came from outside
DEC at the same time DEC was rapidly losing interest in the
PDP-11 products. It and the 11/93 were intended as a "last
hurrah" for DEC-branded PDP-11 stuff. The idea was that just
about anything could be replaced by that pair of boards (and
possibly the Univerter if going into a Unibus chassis).

The reason you never saw an RQZX1 on any VAXen was that the
setup menus were accessed by booting from a special drive unit
number, and the code you got was the setup utility for the
RQZX1. Since it had no VAX code, it was impossible to config-
ure on a VAX - you'd have to set it up using a PDP-11 based
system and then move it to the VAX system.

I asked about this when doing the menus - using a second unit
number to boot VAX code wouldn't have been hard, but I was 
told to just stick to the PDP-11 side. The impression I got
was that none of the VAX groups wanted it. They were either
heavily invested in DSSI or already had their own limited-
function SCSI boards.