9 Feb
2002
9 Feb
'02
5:42 a.m.
On Feb 8, 8:31, Bill Gunshannon wrote:
RX50's came pre-formatted from DEC. There was
never a way to
format them on PDP's or VAX as far as I knew. I do think it is
possible to create them using PUTR and an old PC with a proper
floppy controller and a 1.2M floppy drive configured the right
way.
You can format them on a Rainbow, but not an -11 or VAX.
My understanding is they are 80 track, 96 tpi format
but spin
at the slow spead of normal 5.25 disks and not the higher speed
used by IBM HD disks.
Very similar low-level format to IBM floppies, except that, as Bill says,
they're 80-track. The spec is 80-track, 96 tpi, single-side, double
density (not HD), 10 sectors per track, 512 bytes/sector. DEC squeeze the
extra sector in by shortening some of the gaps; even so the timing is a
little tight and the drive speed has to be better-than-averagely accurate.
It doesn't matter whether you write them at 300 rpm or 360, so long as the
controller adjusts its data rate accordingly (250kbps or 300kbps). Which
is what a PC does (uses 250kbps for 300rpm and 300kbps for 360 rpm).
However, many HD-capable drives use pin 2 on the interface not only to
change the speed but change the write current. Some such drives have
jumpers to set the correct values.
As a curious note, I actually had (and may still have
in the
attic somewhere) a real shugart 80 track 5.25 drive that would
have been the equivalent of an RX50, so it was not only DEC who
used that format. I had them on a TRS-80 and NewDOS-80 and
DOSPlus had no problems formatting and using the drive. This
was long before my first PDP, but I now wonder if they would
have been able to read and write (and maybe even format!) RX50's.
If the controller it was attached to can write MFM (double-density), then
it would work. Drives of that type were very common before PCs took over.
In fact you can fudge one to look like half of an RX50 (a real RX50 plays
funny tricks with the SideSelect and Track00 signals, and some DEC
controllers use that to recognise an RX50).
--
Pete Peter Turnbull
Network Manager
University of York
9 Feb
9 Feb
8:37 p.m.
New subject: [pups] Duh - how do you format an RX50?
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.
It is a *diagnostic* program (not a user program) for formatting these
beasties. Mine is for the -11, I would imagine that there is one for the
MicroVAX as well.
Of course, it is copyrighted.
Jay
At 11:42 PM 2/8/2002 +0000, Pete Turnbull wrote:
On Feb 8, 8:31, Bill Gunshannon wrote:
---
Jay R. Jaeger The Computer Collection
cube1(a)charter.net
RX50's came pre-formatted from DEC. There
was never a way to
format them on PDP's or VAX as far as I knew. I do think it is
possible to create them using PUTR and an old PC with a proper
floppy controller and a 1.2M floppy drive configured the right
way.
You can format them on a Rainbow, but not an -11 or VAX. 
11:14 p.m.
New subject: [pups] Duh - how do you format an RX50?
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.
It is a *diagnostic* program (not a user program) for formatting these
beasties. Mine is for the -11, I would imagine that there is one for the
MicroVAX as well.
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, everyone
at that time knew there were only 3 manufacturers of platens and everybody
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.
By the way, I mnentioned having a n on-DEC 80 track 5.25 drive. I was
wrong about one thing, though. It was not a Shugart, it was a Tandon.
Sadly, I don't think I still have it.
But I think it is time to dig up some drives and controllers and see
just what can be done to create RX50 diskettes. Who know, maybe I can
take over the business that DEC had. Hmmm. I think they used to get
$10.00 a diskette. They're rarer now. Maybe $25.00 each?? Yeah, that's
the trick. I'll tell my daughter she can register for the next semester
now.... :-)
Of course, it is copyrighted.
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.
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 drives
all the time and never had a problem. Is this perhaps another myth intended
to foster the sale of pre-formatted diskettes??
bill
--
Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
bill(a)cs.scranton.edu | and a sheep voting on what's for dinner.
University of Scranton |
Scranton, Pennsylvania | #include <std.disclaimer.h>
10 Feb
10 Feb
5:27 a.m.
New subject: [pups] Duh - how do you format an RX50?
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.
It is a *diagnostic* program (not a user program) for formatting these
beasties. Mine is for the -11, I would imagine that there is one for
the MicroVAX as well.
The "RX50" at the end of the title may just mean that the floppy is in
RX50 format, not that the diagnostics contained therein can format RX50s.
I'd almost be willing to bet money on that, since the Micro PDP-11
originally used the RQDX1 to control the RX50, and a disassembly of
the RQDX1 firmware shows no evidence of floppy formatting code.
11 Feb
11 Feb
5:23 a.m.
New subject: [pups] Duh - how do you format an RX50?
Rats. So it would seem. Forgot about that angle. Useful program -- just
not for floppies.
Oh well.
(Hmm. I wonder how "bzzzzt"s taste when you have to eat them with your
hat?) I suspect that they kind of tingle, eh?
Jay
At 03:27 PM 2/9/2002 -0800, Eric Smith wrote:
---
Jay R. Jaeger The Computer Collection
cube1(a)charter.net
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.
It is a *diagnostic* program (not a user program) for formatting these
beasties. Mine is for the -11, I would imagine that there is one for
the MicroVAX as well.
The "RX50" at the end of the title may just mean that the floppy is in
RX50 format, not that the diagnostics contained therein can format RX50s.
I'd almost be willing to bet money on that, since the Micro PDP-11
originally used the RQDX1 to control the RX50, and a disassembly of
the RQDX1 firmware shows no evidence of floppy formatting code.
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