16 Oct
2012
16 Oct
'12
1:29 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Jay West
Sent: 16 October 2012 00:43
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: unibus to modern disk interface?
Most of the discussion on this that other people have brought up, is why I
liked Brad Parkers "udisk" approach so much. His design goals
were:
Create a low cost unibus adapter card which can emulate a small number of
popular controllers (RL11, UDA50, etc) and use an IDE or CF disk as the
actual media.
Make it easy for others to write personality modules for different
controllers.
Should allow use of a IDE/CF disk to boot a PDP-11 (or vax).
Specifically, I was enamored of the approach that allowed a user to write
their own personality module to change it from acting like a SCSI
controller
vs. SDI vs. etc.... all via software. This would seem
to me to be the most
functional approach for the most people.
I'll pony up a bounty of $300 to get someone to take those design goals
through to a kit form. Anyone want to add to the bounty? Or take up the
gauntlet? :)
J
I think there are actually two approaches, depending on what hardware you
have already.
The first is the udisk approach. That allows you to emulate any card for the
bus that the card is designed for. You would need different cards for Unibus
and for Qbus, and I suspect for some protocols like MSCP it the software
might be hard to write, not well documented etc.
The second is to emulate at the disk interface. For example the MFM
interface for RD53/54 like I am interested in, or SCSI. In this case you
need different cards for different interface technologies but could use
existing controller. I like this approach more because you have more of the
original hardware, but recognise that not everyone will have that hardware
(I have a few RQDX3, one KZQSA, but I don't have, and really want, a KFQSA).
I have a few RD53/54 that will last me a while but when they are gone they
are gone, and I find it increasingly hard to find sub 1GB 50-pin SCSI, so I
want to emulate at that level. Don't have the design ability really but I
may try to breadboard something some day. I think this solution may also be
easier to get parts for, particularly the line drivers, which seem to be
hard for Qbus.
Regards
Rob