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

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

[Jonathan Engdahl]

I can't believe I haven't figured this out yet. I bought an
RX50, and installed it in my PDP-11/53 running 2.11BSD. It's
nice having that empty hole in the front of the BA23 plugged,
but I hope for even more. The drive seems alive: if I say "cp
/dev/ra1a /dev/null", it starts groaning and ticking as if it
were reading the floppy.

But how do you format the floppies?

I tried XXDP/ZRQCH0 (downloaded via VTserver), but it says the
floppies are UNFORMATTABLE. That does that mean?

--
Jonathan Engdahl                    Rockwell Automation
Principal Research Engineer         1 Allen-Bradley Drive
Advanced Technology                 Mayfield Heights, OH 44124
http://users.safeaccess.com/engdahl engdahl at safeaccess.com

"The things which are seen are temporary,
 but the things which are not seen are eternal."  II Cor. 4:18

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

[Bill Gunshannon]

On Fri, 8 Feb 2002, Jonathan Engdahl wrote:

> I can't believe I haven't figured this out yet. I bought an
> RX50, and installed it in my PDP-11/53 running 2.11BSD. It's
> nice having that empty hole in the front of the BA23 plugged,
> but I hope for even more. The drive seems alive: if I say "cp
> /dev/ra1a /dev/null", it starts groaning and ticking as if it
> were reading the floppy.
>
> But how do you format the floppies?
>
> I tried XXDP/ZRQCH0 (downloaded via VTserver), but it says the
> floppies are UNFORMATTABLE. That does that mean?

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.

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.

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.

bill

-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
bill at cs.scranton.edu     |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>

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

[Pete Turnbull]

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

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

[Jay Jaeger]

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:
>
> > 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.


---	
Jay R. Jaeger					The Computer Collection
cube1 at charter.net

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

[Bill Gunshannon]

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 at cs.scranton.edu     |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>

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

[Eric Smith]

> 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.

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

[Jay Jaeger]

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:
> > 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.

---	
Jay R. Jaeger					The Computer Collection
cube1 at charter.net

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

[Pete Turnbull]

On Feb 9,  8:37, 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.

> At 11:42 PM 2/8/2002 +0000, Pete Turnbull wrote:
> >You can format them on a Rainbow, but not an -11 or VAX.

Jay, I'd be very interested to know more about that.  I never heard of it
before, and I thought I had a pretty comprehensive collection of the PDP-11
(including microPDP-11) diagnostics.  Was it standard issue with a
particular model?  Is there a date on it?

-- 
Pete						Peter Turnbull
						Network Manager
						University of York

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

[Pete Turnbull]

On Feb 9,  8:37, 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.

Jay, I just checked on that.  It's not an RX50 formatter, it's the XXDP V2
formatting and diagnostics routines for an RXDX3.  IIRC it will format RD5x
hard drives, and RX33, but not an RX50.  Can you get a directory listing of
the disk?

-- 
Pete						Peter Turnbull
						Network Manager
						University of York

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

[Pete Turnbull]

On Feb 10, 17:23, Jay Jaeger wrote:
> 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?

As far as I remember, yes.  I've tried it a few times myself :-)


-- 
Pete						Peter Turnbull
						Network Manager
						University of York

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

[Pete Turnbull]

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,
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.

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
drives
> all the time and never had a problem.  Is this perhaps another myth
intended
> 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