5 Jan
2021
5 Jan
'21
9:36 a.m.
On Jan 5, 2021, at 11:00 AM, Warner Losh <imp at
bsdimp.com> wrote:
On Tue, Jan 5, 2021, 7:20 AM Paul Koning via cctalk <cctalk at classiccmp.org>
wrote:
...
I don't know about FreeBSD, but you don't need special drivers on DOS or Linux.
In DOS, it's just some int 13 magic. In Linux, it's an ioctl to set the floppy
layout.
I did this a long time ago for my "flx" utility (RSTS file access on a PC). The
initial version was for DOS, and that code should still work. I added Linux support
later. There are two versions of this code: one in C (flx 2.6) for DOS and Linux; that
one on Linux needs to have the layout set via a Linux utility first. The other is flx 3.0
which is written in Python; it handles everything directly. That version also includes a
separate utility that just does interleave or de-interleave of 800 block disks and
container files, so you can create a SIMH compatible disk image from a floppy, or a Xhomer
interleaved layout image from a regular (logical order) image. That simply uses the disk
access code from FLX with the file system pieces left out, so it isn't specific to
RSTS.
In my experience (admittedly only on a few PCs I have had that include a 5.25 inch floppy
drive) both reading and writing work with no trouble at all. For my Pro development
I've always used floppies as the transfer medium, which means creating bootable RSTS
disks on the PC. Works fine.
paul
As for floppies, the RX50 format is the same for
all PDP-11/VAX systems. Unlike hard drives, Pro floppies and RQDX3 floppies are
identical. The geometry is handled in the host for the Pro and in the controller for the
RQDX case, but it's the same geometry. And by the way, a PC floppy drive can handle
RX50 floppies without any trouble, if you set it to the correct geometry -- in particular,
you have to tell it there are 10 sectors per track rather than the PC default of 9
sectors.
Reading this is true. There are several drivers for this for DOS, linux and
FreeBSD (though the latter may be out of tree). Writing on PC and reading on a Rainbow is
possible, but it is unreliable because the 1.2M drives aren't that good at writing
lower the lower density data rates.