DEC RXV21 with 5.25 floppy - test-drb@ccmp.vtda.org

27 May 2001

On May 27, 20:37, jkunz(a)unixag-kl.fh-kl.de wrote:

...
  I decided to write a NetBSD driver for the DEC QBus
RXV21 8" floppy
 controller. Unfortunately I have only two controllers, no 8" drive nor
 medium. I thought that this would'nt be a problem, as it is possible to
 connect a 5.25" drive to a 8" floppy controller. 
Yes, but you've not got a controller.  You've only got the QBus interface
that taslks to the controller, which is in the RX02 chassis.  Unless what
you have is a Plessey or General Robotics RXV21 (GXV21?) which connects to
8" that have an SA800/SA850 interface.  That, however, is a very different
animal.

...
  But the medium needs to
 be reformated. Now that I have the controller doc, I had to read that
 the RXV21 can not format a floppy. It needs preformated media. 
Well, if you have a real RX02, it can "reformat" RX01 disks.  I doesn't
actually reformat them in the sense that is usually meant, though.  It
takes a disk already formatted with 128-byte single-density sectors (IBM
standard) and rewrites the data portion of each sector (NOT the headers,
which remain FM) as 256-byte blocks in MFM.

...
  Would it be possible to use some other machine* with
5.25" floppy drive
 to format the 5.25 media an way that the RXV21 can read it? 
You could use a PC to format a disk so it looked like a single-density 8"
disk laid out the same way as an RX01 disk.  To do that, you'd need a
suitable drive, and controller that can handle 250kHz data in FM
(single-density).  Your RQDX controllers certainly can't do it.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York