On Fri, Oct 20, 2023 at 1:46 PM Henry Bent <henry.r.b...@gmail.com> wrote:
> I have a SIMH installation of Ultrix-11 3.1 on RL02 drives.  Two RL02s is 
> enough for a base system and four (which would be what the DQ614 provides, if 
> it worked) would be more than enough for sources and work, etc.

Yes.  40MB should be plenty of room.  10MB was definitely not enough
for 2.9BSD, but at the time, I only had one RL02 drive.

> The Ultrix-11 RL driver does fancy things with overlapped seeks that I'm sure 
> works on real hardware but on the DQ614, not so much.

Ah... I can see that.  It wouldn't surprise me if the DQ614 got most
of its development and testing with RT-11 in mind, and possibly some
RSX-11.

I remember that the DEC RL controller (at least for PDP-11, not as
sure about the RL8A) did support some pretty handy things for a
multi-user OS, like overlapping seek, but I think in all the years I
worked with DEC gear, only a few machines had multiple RL drives.
Mostly I saw them as data transfer devices or for primary storage on
small (single-user) systems.

We did have one larger system, an 11/24 with four RL02, running RSTS/E
and whatever we were using for accounting software.  I didn't work on
the machine myself except to physically disconnect and pack and move
it from one site to another when we consolidated our operations back
into one building.

-ethan

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