[pups] Duh - how do you format an RX50?

Pete Turnbull pete at dunnington.u-net.com
Sun Feb 10 04:40:21 AEST 2002

On Feb 9, 12:14, Bill Gunshannon wrote:
> On Sat, 9 Feb 2002, Jay Jaeger wrote:
> > Um, bzzzzt.  Wrong.  I have a floppy labeled:  BL-FN7AP-MC CZFNAP0 M-11
> > FORMTR RX50  .  This is a formatter program for a Micro PDP-11.

> I guess this constitutes the last straw for this myth.  Or was it merely
> a business decision intended to promote the sale of pre-formatted RX-50
> diskettes. (A practice not uncommon in those days.  For example, at one
> place where I worked we were responsible for maintaining Terak Micros, a
> LSI-11 based system.  Any time we reported a floppy problem the first
> question was, "Are you using Terak brand diskettes??"  Of course,
> at that time knew there were only 3 manufacturers of platens and
> else just supplied labels!!)
> Other arguments:  I have an Andromeda Disk Controller.  I know one of the
> supported floppy formats is RX50.  I'll bet the their formatting program
> won't care what drive is there and will happily format diskettes for use
> in this and other RX-50's.

I expect it would.  It's not hard to write a formatter program.  I wrote
one for my Acorn Archimedes, and an RX50 copier program as well.

> I wonder if there is anyone who could be contacted about releasing it??
> Maybe even the VMS version, too.  Or even, the source??  Somehow, I doubt
> that Compaq still sells many pre-formatted RX50's.

I seem to recall that DEC let people copy XXDP between machines without too
much excitement.

> And while we're on the subject, what about this supposed problem using
> anything put certain kinds of diskettes??  I used my 80 track 96tpi drive
> all the time with the same diskettes I used in my other SS/SD, DS/SD
> all the time and never had a problem.  Is this perhaps another myth
> to foster the sale of pre-formatted diskettes??

So long as they're labelled SD or DD and not HD, they have the right
coercivity.  Some people argue that the fineness of the emulsion may be a
factor, but actually you'd have to be incredibly unlucky to have a flaw on
a disk that would allow it to be perfect for SD but not DD.  Some people
have likewise argued that the disk head gap is only about half as wide for
80-track as it is for 40-track, but that's irrelevant: even if the gap is a
third of the track pitch, thats around 1/300", the resulting bit density
(300 bpi) on the radius of the disk is still much coarser than the bit
density around the circumference (about 3300 bpi for single density).

I do have a few very old S/S floppies with flaws on the second side, and
which therefore aren't good to use as D/S (I value my data!) but I have
hundreds more sold as S/S that are work fine as D/S.  They just weren't
certified that way; they probably just weren't tested, in the days when
lots of disks didn't need to be.

Pete						Peter Turnbull
						Network Manager
						University of York

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