Datasystems Design Board + RX33 floppies

From: Jerome Fine <jhfine_at_idirect.com>
Date: Fri Aug 3 18:40:47 2001

>Sergio Pedraja Cabo wrote:

> Is there anybody out there (mainly in Europe) that could send
> or purchase me one of this DSD monsters ?

Jerome Fine replies:

I don't know about the market in Europe or how available Qbus
hardware is, but do you realize how much a DSD 880/30 weighs?
My sore back says it is more than 50 lb. although I am sure the
scale says it is somewhat less. Of course, that is the unit with
ONE 8" hard drive that looks like 3 * RL02 and ONE 8" floppy
drive that is compatible with a single RX02 floppy drive from
DEC - in addition, the actual drive hardware is able to use
double-sided media and if enhancements are made to the standard
DEC device drivers, then the operating system can use both
sides - which means that each floppy diskette has 1976 blocks
instead of only 988 blocks.

If the actual unit you mean is only the DSD 440, that is only the
dual 8" floppy which is also RX02 compatible.

I remember using the DSD 440 more than 20 years ago. The
company I worked for back in 1978 had the DSD 440 for which
two controllers had been purchased. One controller with that
26-pin cable came from a PDP-11/34. There was also a second
cable available which came from a VT103. I guess what amazed me
the most was that an identical floppy could boot RT-11 even
though there were a very few but extremely significant differences
in the instruction set for the PDP-11/34 CPU and an LSI-11/02 CPU.
Of course, now that I have seen the actual code in RT-11 which takes
care of those differences, I understand how it is done. BUT, back
in 1978 I was very surprised.

Sergio, why do you want the DSD 880/30? If you have a controller
which emulates the RL02, why not use that? Better still, if you have
an RD52, why not purchase an RQDX3? Perhaps you can even
find one for free. If the only hardware that you had was an RL02
or a DSD 880/30, then I agree it is better than nothing. But given the
choice, if you are going to acquire hardware, try and get an RQDX3
with either an RD52 or an RD54. I would recommend against getting
an RD53 unless you already have one - if so, be sure that you don't
rely on only one RD53 since these days they have a very high failure
rate.

I hope this answers some of your concerns,

Sincerely yours,

Jerome Fine
Received on Fri Aug 03 2001 - 18:40:47 BST