Archiving 8" RT-11 floppies to CD-ROM?

Ethan Dicks ethan.dicks at
Wed Feb 25 13:47:24 CST 2009

On Wed, Feb 25, 2009 at 2:34 PM, Chuck Guzis <cclist at> wrote:
> On 25 Feb 2009 at 14:12, Ethan Dicks wrote:
>> On Wed, Feb 25, 2009 at 1:36 PM, F.J. Kraan <fjkraan at> wrote:
>> > Just recently I was able to read my MiniMINC (a PDT-150) floppies with an 8"
>> > drive connected to an AHA1542B (capable of single density) with Dave
>> > Dunfields ImageDisk.
>> Good to know.  I have at least one 1542B running around, and an old
>> DOS box I can use to stuff it all into.
> Depending on chipset, many modern PCs can handle single-density just
> fine--no need for a separate controller.  There are lots of old ISA
> cards with floppy controllers out there than can handle single
> density, not just the 1542--basically anything with a WD37C65,
> National 8473/8477 will work--and there are others.

Right, but back in the day, I didn't have MFM or 40-200MB IDE drives -
I had SCSI since I came from Macs and Amigas.  I wouldn't have ever
had a machine with 5.25" floppies without SCSI hard disks.  Any
pre-Pentium machine I happen to have on the shelf would have a 1542A,
B or C already.

> But if we're talking about RX02-style double-density media, nothing
> short of a Catweasel is going to help.  The RX02 double-density
> format is DEC-unique, essentially FM sector headers with MFM data--
> and funny MFM at that, with codes selected not to conflict with those
> used as AMs in FM data.

Of course.  I do have both RX01 _and_ RX02 media, so it's probably
just best to set up a PDP-11 w/RX02 and vtserver.  It's not like I
don't already have 100% of the parts on hand.

> A Tandon 848 should be fine in any case.

Good to know.  Mine happens to be attached to a 3rd party controller
(it came in a Dataram chassis with a Rodime 10MB disk imitating an
RL02 via a DQ614), so it _can_ lay down RX01 headers on a blank disk.
I haven't ever had to do it, but it might come in handy some time.


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