17 Jan
2005
17 Jan
'05
2:34 p.m.
Patrick Finnegan wrote:
Doc Shipley declared on Monday 17 January 2005 11:04
pm:
Oh.
<Emily LaTella>
Never mind.
<Emily>
Doc
Dwight K. Elvey wrote:
Umm, the RX50s and Altos 580 floppies you've used are 80-track (96tpi)
disks just like 1.2MB floppies. 360k floppies are 40-track (48tpi)
disks. So, they're the same track width as a 1.2MB disk, not a 360k
disk. 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.