On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:
> On 2/26/23 16:42, Chris Zach via cctalk wrote:
> > Oi.
> >
> > So after finally getting things going I started copying the Pro/380 OS
> > files to a bunch of 1.2mb floppies. Great. However after a bit I started
> > getting errors, and found that the disks were getting gouges in the
> > tracks. Sure enough disassembly of my 1.2mb Teac showed that debris had
> > become embedded in the disk head and cleaning is not possible.
> >
> > Terrific. Tossing the drive, this is not the first time I have had this
> > problem with these disks so I am dumpstering all of the old floppies and
> > just bought 40 new ones in sealed boxes.
> >
> > However I'm now in need of a 1.2mb floppy drive. Anyone have a good
> > working spare that I can beg/borrow/buy in the MD area?
>
> I thought the Pro 300 series used RX-50 drives; i.e. 400K 96 tpi DD
> media. So even with your 5.25" HD drive, you should be using DD
> ("360K") floppies.
>
You should be using QD floppies, but those are rare. DD floppies from later
than
1985 though work just fine (discovered empirically while a poor college
student,
reconfirmed recently when I made all those Venix disks).
However, in a PC, to write these diskettes, you need a 1.2M drive. While
there is a couple of TEAC drives (55FR I think) that do 80-tracks at the
DD/QD
RPM and data rates, things get fussy putting them into PCs. And last time
I looked they were 5x the price of ye-olde-generic 1.2M floppy drive. As
long
as it's formatted at the right density/rpm rates, it's fine. And RX50.SYS,
if memory serves, does all that right.
Using 3.5" drives in double density mode will work, but there's a cascade
of software issues you'll have to deal with. I booted my DEC Rainbow with
these and some hacks from someone in the Jemez Mountains to do double
sided on MS-DOS (which reminds me, I have the hacks still, and they also
have a now lost-ish BIOS listing for 3.10b, so I should see if I can post
that for the few people still interested).I've never done it on a PRO
though.
I'm out in Colorado, or I'd happily give you one of my spares.
Warner
