27 Feb
2023
27 Feb
'23
9:55 a.m.
On Feb 27, 2023, at 9:50 AM, Warner Losh via cctalk
<cctalk(a)classiccmp.org> wrote:
On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
cctalk(a)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