Installing an operating system on the 11/83 - update.

[Warner Losh]

On Tue, Feb 22, 2022 at 5:01 PM Ray Jewhurst <raywjewhurst at gmail.com> wrote:

> I read that you can indeed use a standard 1.2 Meg drive and that you can
> also use DSHD 5.25 disks in place of RX50s. Is there any truth in this? If
> there is it will be much easier and cheaper to make disks for my Rainbow.
>

I'd avoid the HD diskettes, since they are designed for the recording rates
/ magnetic field densities of the 1.2 floppies. Some people have done it
successfully, though. Back in the day, there were many reports of people
doing this in their new AT or newer computers, but with a elevated error
rate... good enough for data transfer most of the time, but you'll
occasionally need to rewrite them.

I've successfully used DSDD disks in place of the now rather rare DSQD
disks. Based on long-term read back from disks I did this with in the 80s
and 90s, I'd say the retention is a bit worse, but if you are just making a
distribution set and reading it right away, you won't go far wrong. After
30 years, the failure rate was like 5%, back in the day it was closer to
1%, so I'd expect that now. It's what I did when I burned copies of the
Venix/86 disks to boot on my Rainbow... I've done it with both RX50.SYS and
a 1.2M drive on a DOS back years ago, and with a real RX-50 back in the
day, and just recently. Though come to think of it, all the disks were
formatted on my Rainbow under DOS with the hard format option....

Warner


> Sent from my Verizon, Samsung Galaxy smartphone
> Get Outlook for Android <https://aka.ms/AAb9ysg>
> ------------------------------
> *From:* cctalk <cctalk-bounces at classiccmp.org> on behalf of Warner Losh
> via cctalk <cctalk at classiccmp.org>
> *Sent:* Tuesday, February 22, 2022 6:42:38 PM
> *To:* js at cimmeri.com <js at cimmeri.com>; General Discussion: On-Topic and
> Off-Topic Posts <cctalk at classiccmp.org>
> *Cc:* General at ezwind.net <General at ezwind.net>
> *Subject:* Re: Installing an operating system on the 11/83 - update.
>
> On Tue, Feb 22, 2022 at 4:36 PM js--- via cctalk <cctalk at classiccmp.org>
> wrote:
>
> >
> > Rod,
> >
> >    Not sure an RX33 (if 1.2MB
> > equivalent) would write working RX50
> > 800k (double density) disks.  Very
> > different drives.
> >
>
> The RX-33 is the same sort of drive that you had in your PC if you wrote
> RX-50s with your PC. Back in the day, lots of people used RX50.SYS to
> have it setup the transfer rates, RPM and sectors per track parameters
> so that you could read/write them on a PC running DOS. The parameters
> are basically the same ones you need to write the 360k DOS floppies, only
> with twice the number of tracks and 10 sectors per track instead of 9 (this
> is
> done by making the track gaps smaller and eeking an extra sector out of the
> deal, but using at the same data rates).
>
>
> >    I've successfully put an actual RX-50
> > drive on my PC, and written RX-50 images
> > using PUTR.  You might try that route.
> >
>
> Did you have difficulties with Pin34 not being the change disk pin? That's
> what
> I ran into when I tried this many many years ago...
>
> Warner
>
>
> > - John Singleton
> >
> > On 2/22/2022 11:20 AM, Rod Smallwood via
> > cctalk wrote:
> > > Hi All
> > >
> > >       I did find some RX50 images of
> > > the MicroRSX distribution.
> > >
> > >      So I fired up my DEC Celebris FX.
> > > It runs W95 and has a 3.5 inch floppy,
> > > a real RX33 5.25 inch drive and a CD-R.
> > >
> > >    Its accessible on my network so
> > > getting files onto it is not a problem.
> > >
> > >     So install putR.com , and transfer
> > > the image files.
> > >
> > >     Huh! putR says the RX50 disk is
> > > write protected. Its not and the drive
> > > works normally with the disk from the
> > > MS DOS prompt.
> > >
> > >      So much for putR writes RX50's on
> > > RX33!
> > >
> > >     Rod
> > >
> > >
> > >
> > >
> >
>