17 Jan
2005
17 Jan
'05
2:04 p.m.
Dwight K. Elvey wrote:
Hi Eric
I think he means that as long as he stays on that drive,
he has no issues. The write problem is obvious to anyone
that thinks about it a little ( I hope ).
I don't just stay on that drive. If I did, I wouldn't need it in the
first place.
1. A truely blank disk ( bulk erased ) can be
formatted
and written on by a 1.2M drive and will work in most
cases on a 360K drive. This may written on by a 360K
drive as well and still work on a 360K.
2. Once a disk has been written on first by a 360K drive
and then a 1.2M, it can only be read on a 1.2M drive!
That's life.
No, that's wrong. At least, it's not necessarily true.
I have formatted disks for an RX50 on the 1.2MB drive, written data
to them on that drive, and used them on a PDP-11. I have also used
floppies to back up an RSX-11S disk on "real" RX50 disks, transcribed
that to PC, overwritten them on the PC without a low-level format, and
read them on the PDP-11. I have had some floppies fail, but they always
failed either on the RX50 drive *before* they were ever in the 1.2MB
drive, or they failed format on the 1.2MB drive before they ever made it
to the PDP-11.
I don't doubt the information I'm reading, that the track written by
the 1.2MB drive is narrower than the track written by a native 360K
drive. I'll even stipulate that my experience is limited to writing
disks for PDP-11s and the Altos 580 (DSQD I think; I haven't played with
that box in a long while), so I can't speak to the reliability on other
platforms.
I *can* say that in writing, overwriting, transcribing, and reading
RX50[0] floppies between a real PDP-11 and a Linux PC with a 1.2MB 5.25"
drive, track width has never been an issue. The few disk failures I've
had never got far enough to bring that into play.
Doc
[0] Both original NIB RX50-formatted 3M floppies, and 1.2MB DSHD
floppies formatted according to Pat Finnegan's fdformat/superformat
parameters.