> On Feb 27, 2023, at 9:50 AM, Warner Losh via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
> cctalk@classiccmp.org> wrote:
>
>> ...
>> 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.
Yes, the Pro uses RX50 drives.
> 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.
I don't understand that. I have a plain old Gateway PC with a twin floppy
drive (3.5 and 5.25 pair). It defaults to PC format 9 sectors per track, of
course. But it's quite happy to be told to do 10 sectors per track, reading or
writing. I first did so using DOS with INT13 I/O, then in Linux with a fdparm
operation, and finally in C or Python by issuing an appropriate FDSETPRM ioctl.
Works great.
You can find the machinery in my "flx" utility (for operating on RSTS file
systems); it handles both container files and actual RX50 format floppies.
This is how I write disks for my Pro to consume.
paul
