DEC RK07 drive interface specs wanted

From: Paul Koning <>
Date: Thu May 13 20:15:33 2004

>>>>> "Ethan" == Ethan Dicks <> writes:

 Ethan> On Thu, May 13, 2004 at 10:34:22PM +0100, Tony Duell wrote:
>> > The real question is: What is more time consuming? Rebuild the
>> RK07 or > build a solid state RK07 replacement.
>> It also depends on what you want to do. To me, a classic computer
>> system is more than just the CPU. The peripherals are part of it
>> as well. Running a PDP11 with flash memory mass storage is not
>> the same as running one with a demountable hard disk.

 Ethan> While in principal I agree, in years gone by, I was unable to
 Ethan> do more than play-load 2BSD on a real 11/24 because my largest
 Ethan> Unibus disk (that wasn't on a UDA-50) was and still is RL02s
 Ethan> on an RL11. These days, I have bigger Unibus CPUs (11/44,
 Ethan> 11/70), but in terms of pre-MSCP disks, 10MB is still a limit
 Ethan> for me (fortunately, I can get around this with 2.11BSD on the
 Ethan> 11/44 or the 11/70, but 2.9BSD was it for non Split I&D
 Ethan> machines)

 Ethan> Even though I appreciate and admire the older disks, I'm
 Ethan> pretty much stuck with RK05 and RL01/2. I'd love a solution
 Ethan> that emulates _some_ DEC disk controller (to avoid burning
 Ethan> boot PROMs, writing drivers for every OS I'd want to play
 Ethan> with, etc.). In order, a good solution for me would work with
 Ethan> 2BSD, RT-11, RSX and RSTS... there's plenty of interfaces that
 Ethan> fit the bill.

If you can find adequate documentation for MSCP -- which should be
doable -- then an MSCP controller would make a lot of sense. It's
more complex in a sense, but it's command packet oriented, so the CSR
piece is trivial. That one you can definitely do with just a register
file to provide a register window (plus a DMA, but that can actually
just be controller software reaching through a memory window over the

One clear advantage is that you can pretty much pick whatever device
size you want, because drivers query the controller for the disk size
and believe what they are told. With older devices, you're stuck with
the particular device sizes that existed then.

If not MSCP, the next obvious choice is RH11, because that gives you
the widest choice of the biggest drives, and it doesn't seem
significantly harder than any of the others.

Received on Thu May 13 2004 - 20:15:33 BST

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