27 Jul
2004
27 Jul
'04
7:34 a.m.
I'm working on a PC-based external 8" floppy drive, mostly to be able
to format the 30-40 pounds of perforated placemats (aka bulk-erased RX02
disks) in my garage, and to be able to archive the few PDP-8 and Xerox
systems disks, games disks, diags and source disks I have, but don't
have the equipment to run. I've discussed this in pieces here, but I'm
ready to try to actually put it all together.
The first order of business is an interface cable for a standard ISA
floppy/IDE controller. I've found this pinout:
http://tinyurl.com/5c5fb
but no confirmation that it actually worked with a YD-180 drive,
which is what I have available.
Second issue is powering the drive. YE Data's schematics say +24VDC,
max 1.0A, typical 0.4A, and 5VDC, max 1.0A and typical 0.4A. However,
I've also found Usenet posts claiming a peak draw of 24VDC(a)2.2A and
5VDC(a)1.7A, so I'm inclined to be generous. I'm also not at all versed
in electronics, so I'm not sure what to look for past those specs.
Jameco has these units:
http://tinyurl.com/3lpjc
PWR SPLY,SWITCH(D-60B)58W, 5V@3A,24V@1.8A,UL/TUV/CE
Jameco #123465
http://tinyurl.com/4whtu
PWR SPLY,SWITCH,45W,5VDC@5A, 24VDC(a)1.8A,PFC,UL/CSA/CE/TUV
Jameco #194870
http://tinyurl.com/6fpp9
PWR SPLY,SWITCH,65W,5VDC@6A 24VDC(a)2.6A,PFC,UL/CSA/CE/TUV
Jameco #194896
http://tinyurl.com/64rml
PWR SUPPLY,SW,65W,5V/7A, 12V/3.2A,2.4V/1.5A,MIN,LOADREQ
Jameco #215706
Which is most suitable for an external floppy enclosure? If "none of
the above", what am I missing?
At the risk of heresy, right now I don't have time to be educated in
the issues; just point me in the right direction and shove, please. :)
BTW, I'll be more than glad to list and share the software I have.
After it's archived, I'll be looking to give away the disks I can't use,
or trade them for blanks.
Thanks,
Doc
27 Jul
27 Jul
8:22 a.m.
On Tuesday 27 July 2004 14:34, Doc Shipley wrote:
I'm working on a PC-based external 8"
floppy drive, mostly to be
able to format the 30-40 pounds of perforated placemats (aka
bulk-erased RX02 disks) in my garage, and to be able to archive the
few PDP-8 and Xerox systems disks, games disks, diags and source
disks I have, but don't have the equipment to run. I've discussed
this in pieces here, but I'm ready to try to actually put it all
together.
Oh, one thing to remember... RX01's use single-density (FM) encoding,
and RX02's use a mixed-density (FM for sector headers + MFM for data)
encoding. You won't be able to read RX02's for sure (and probably also
RX01s due to their header format) on a PC's floppy disk controller.
Somethink like a CatWeasel or other similar controller probably could do
the trick, or you could build your own disk controller. :)
Pat
--
Purdue University ITAP/RCS --- http://www.itap.purdue.edu/rcs/
The Computer Refuge --- http://computer-refuge.org
8:32 a.m.
New subject: Amiga CatWeasel? Was: Re: 8" floppy project
Patrick Finnegan wrote:
On Tuesday 27 July 2004 14:34, Doc Shipley wrote:
I'm working on a PC-based external 8"
floppy drive, mostly to be
able to format the 30-40 pounds of perforated placemats (aka
bulk-erased RX02 disks) in my garage, and to be able to archive the
few PDP-8 and Xerox systems disks, games disks, diags and source
disks I have, but don't have the equipment to run. I've discussed
this in pieces here, but I'm ready to try to actually put it all
together.
Somethink like a CatWeasel or other similar controller
probably could do
the trick, or you could build your own disk controller. :)
So is there an RX0x driver for the Amiga CatWeasel? I have an
S-class CatWeasel, but I haven't done much more than glance through the
docs.
2:56 p.m.
On Tue, 27 Jul 2004, Doc Shipley wrote:
The first order of business is an interface cable
for a standard ISA
floppy/IDE controller. I've found this pinout:
http://tinyurl.com/5c5fb
but no confirmation that it actually worked with a YD-180 drive,
which is what I have available.
That'll depend on some details and jumpers of the YD-180,
such as Disk Change v Ready, etc.
You might want to look at
http://www.dbit.com
(they also peddle a 5.25 to 8 inch adapter)
http://www.dbit.com/fdadap.html
Some PC FDCs will read single density, but
you'll need different hardware to handle the "mixed density" stuff.
3:46 p.m.
Fred Cisin wrote:
On Tue, 27 Jul 2004, Doc Shipley wrote:
Define "different hardware"? I have Amigas and an Amiga Catweasel
(Mk2, unfortunately), Macs from SE to G5, DEC (from RX02 to RX50, RX33,
and RX23, as well as the standard interface on later Alphas), and a
weird Siemens-Nixdorf MIPS box that also has a 3.5" floppy.
Bottom line requirement is that I be able to low-level format an 8"
floppy to RX02 format. IIRC, RT-11 can flip the switch from RX01 to
RX02 in an RX02 drive, right?
And I need to be able to accurately copy a bootable RX02 diskette to
a formatted blank.
I'd *like* to be able to take a disk image of a floppy as a file, and
to write that back out to floppy, but that's gravy.
Oh, and the PDP-11/04 I uncrated today has an SMS FD1100I board in it
that looks like a floppy controller, but I can't find out *anything*
about that.
Doc
The first order of business is an interface
cable for a standard ISA
floppy/IDE controller. I've found this pinout:
http://tinyurl.com/5c5fb
but no confirmation that it actually worked with a YD-180 drive,
which is what I have available.
That'll depend on some details and jumpers of the YD-180,
such as Disk Change v Ready, etc.
You might want to look at
http://www.dbit.com
(they also peddle a 5.25 to 8 inch adapter)
http://www.dbit.com/fdadap.html
Some PC FDCs will read single density, but
you'll need different hardware to handle the "mixed density" stuff. 
4:07 p.m.
On Tue, Jul 27, 2004 at 10:46:49PM -0500, Doc Shipley wrote:
Bottom line requirement is that I be able to
low-level format an 8"
floppy to RX02 format. IIRC, RT-11 can flip the switch from RX01 to
RX02 in an RX02 drive, right?
Yes. So can OS/8. The "flip" is when an RX02 drive re-writes part of
the sector to double density. That's what makes them so hard to read
on non-DEC hardware - the media becomes both single and double density.
Both RX01 and RX02 disks start off with "Industry Standard" IBM-compatible
low-level formatting, AFAIK. There are third-party DEC-compatible drives
that can take an absolutely blank disk and lay down tracks. I would think
a suitable CP/M system could do the same. Post-1982 hardware is where
things start to get tricky.
And I need to be able to accurately copy a bootable
RX02 diskette to
a formatted blank.
In terms of development and set-up time, I would think a PDP-11 would
be the fastest way to just dup floppies.
I'd *like* to be able to take a disk image of a
floppy as a file, and
to write that back out to floppy, but that's gravy.
That's trivial with a VAX (BACKUP/PHYSICAL). There must be a way with
smaller hardware (2BSD on a PDP-11, perhaps?)
I wonder what it would take to hook a real RX02 up to modern hardware. The
interface isn't complicated, but AFAIK, it would take more than a PeeCee
parallel port to drive it. Similar to hooking up a real Commodore 1541
to a modern machine and siphoning off a physical backup...
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 28-Jul-2004 03:50 Z
South Pole Station
PSC 468 Box 400 Temp -100. F (-73.5 C) Windchill -126.1 F (-87.90 C)
APO AP 96598 Wind 3.7 kts Grid 114 Barometer 673.8 mb (10860. ft)
Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html
4:31 p.m.
Ethan Dicks wrote:
On Tue, Jul 27, 2004 at 10:46:49PM -0500, Doc Shipley
wrote:
OK. I've heard yea and nay on this count.
You're saying that on an RT-11 system (no OS/8 or its hardware to
play with), I can take an "IBM 3740 Compatible" SSSD disk out of the
box, run FORMAT/DOUBLE, and have an RX02 diskette? That would help
quite a lot.
Bottom line requirement is that I be able to
low-level format an 8"
floppy to RX02 format. IIRC, RT-11 can flip the switch from RX01 to
RX02 in an RX02 drive, right?
Yes. So can OS/8. The "flip" is when an RX02 drive re-writes part of
the sector to double density. That's what makes them so hard to read
on non-DEC hardware - the media becomes both single and double density.
Both RX01 and RX02 disks start off with "Industry Standard" IBM-compatible
low-level formatting, AFAIK. There are third-party DEC-compatible drives
that can take an absolutely blank disk and lay down tracks. I would think
a suitable CP/M system could do the same. Post-1982 hardware is where
things start to get tricky. In terms of development and set-up time, I would think
a PDP-11 would
be the fastest way to just dup floppies.
Yep. Getting blanks to dup *to* is still the issue.
> I'd *like* to be able to take a disk image of
a floppy as a file, and
>to write that back out to floppy, but that's gravy.
That's trivial with a VAX (BACKUP/PHYSICAL).
There must be a way with
smaller hardware (2BSD on a PDP-11, perhaps?)
Hmm. I need to see if I have a Qbus RXV21 that can run in a 22-bit
system. Does VMS/VAX support RX02?
Or, yes, there's an RX211 driver in 2.11BSD. Problem is getting it
*on* the Unibus box. There have been "issues". And there's still no
way to LL format the target disk.
I wonder what it would take to hook a real RX02 up to
modern hardware. The
interface isn't complicated, but AFAIK, it would take more than a PeeCee
parallel port to drive it. Similar to hooking up a real Commodore 1541
to a modern machine and siphoning off a physical backup...
Well, there's an interface to make the PC look like an RX02....
Doc
4:47 p.m.
On Tue, Jul 27, 2004 at 11:31:38PM -0500, Doc Shipley wrote:
That's right... I remember that. I always wanted to fiddle with that. Last
I heard, it was working with some hosts and not others (PDP-11 vs PDP-8
differences, mostly). It looked interesting, but personally, my problem is
not enough Omnibus controllers to go into all of my machines, as opposed
to not enough drives to go around.
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 28-Jul-2004 04:30 Z
South Pole Station
PSC 468 Box 400 Temp -99.7 F (-73.2 C) Windchill -132.2 F (-91.2 C)
APO AP 96598 Wind 5.7 kts Grid 103 Barometer 673.6 mb (10868. ft)
Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html
OK. I've heard yea and nay on this count.
You're saying that on an RT-11 system (no OS/8 or its hardware to
play with), I can take an "IBM 3740 Compatible" SSSD disk out of the
box, run FORMAT/DOUBLE, and have an RX02 diskette? That would help
quite a lot.
AFAIK, yes... that's true. The RX01 media that DEC used to sell was
"IBM 3740 Compatible", and that's what I remember doing to "turn"
RX01Ks
into RX02Ks on an RT-11 system. If anyone has any contradictory
information, please feel free to pipe up.
Hmm. I need to see if I have a Qbus RXV21 that can
run in a 22-bit
system. Does VMS/VAX support RX02?
I'm pretty sure VMS supports it, but my only experience is with Unibus
hardware - an RX211 on a VAX-11/750. I would hope that an RXV21 works
in a Qbus VAX, but I can't speak from experience.
Or, yes, there's an RX211 driver in 2.11BSD.
Problem is getting it
*on* the Unibus box. There have been "issues".
Right. I've fiddled with 2.9BSD and gotten over some of those issues
myself. I haven't played at all with 2.11BSD - I've only recently aquired
any hardware that could handle it (KDJ11 CPU card).
And there's still no way to LL format the target
disk.
Of course. This only takes care of part of what you want to do.
I wonder what
it would take to hook a real RX02 up to modern hardware. The
interface isn't complicated, but AFAIK, it would take more than a PeeCee
parallel port to drive it. Similar to hooking up a real Commodore 1541
to a modern machine and siphoning off a physical backup...
Well, there's an interface to make the PC look like an RX02.... 
5:28 p.m.
On Jul 27, 2004, at 10:47 PM, Ethan Dicks wrote:
On Tue, Jul 27, 2004 at 11:31:38PM -0500, Doc Shipley
wrote:
To format, the VMS command is: INITIALIZE/DENSITY=double.
Both QBUS and UNIBUS interfaces are supported.
If you have XXDP for the PDP-11, you can format diskettes on an rx02
using
the ZRXE program. SSSD diskettes work fine.
Mike
OK. I've heard yea and nay on this count.
You're saying that on an RT-11 system (no OS/8 or its hardware to
play with), I can take an "IBM 3740 Compatible" SSSD disk out of the
box, run FORMAT/DOUBLE, and have an RX02 diskette? That would help
quite a lot.
AFAIK, yes... that's true. The RX01 media that DEC used to sell was
"IBM 3740 Compatible", and that's what I remember doing to "turn"
RX01Ks
into RX02Ks on an RT-11 system. If anyone has any contradictory
information, please feel free to pipe up.
Hmm. I need to see if I have a Qbus RXV21 that
can run in a 22-bit
system. Does VMS/VAX support RX02?
I'm pretty sure VMS supports it, but my only experience is with Unibus
hardware - an RX211 on a VAX-11/750. I would hope that an RXV21 works
in a Qbus VAX, but I can't speak from experience.
1 Aug
1 Aug
12:35 p.m.
Ethan Dicks wrote:
I wonder what it would take to hook a real RX02 up to
modern hardware. The
interface isn't complicated, but AFAIK, it would take more than a PeeCee
parallel port to drive it.
I agree that this is true. You can get by bit banging a PC parallel port
as an RX01/RX02 because *that* side sets the pace by driving the clock.
With PC parallel port in standard mode, the best you can do is about a
0.5 MHZ clock, 1 uS high, 1uS low.
The RX01/RX02 specs state a maximum clock of 400ns high and 400ns low.
There is just no way to keep up with that clock without some additional
hardware.
-ethan
-chuck
27 Jul
27 Jul
4:09 p.m.
On Tue, 27 Jul 2004, Doc Shipley wrote:
Different from the PC FDC.
Some PC FDCs
will read single density, but
you'll need different hardware to handle the "mixed density" stuff.
Define "different hardware"? I have Amigas and an Amiga Catweasel
(Mk2, unfortunately), Macs from SE to G5,
I don't remember whether the Amiga can do single density,
but the Catweasel certainly can meet the hardware needs,
although I have no idea what, IF ANY, software is available.
4:36 p.m.
On Tue, Jul 27, 2004 at 09:09:38PM -0700, Fred Cisin wrote:
I don't remember whether the Amiga can do single
density,
I don't recall either. For those that don't know, the Amiga doesn't have
a traditional FDC chip - it uses a massive shift register in the sound chip
to clock pre-encoded data on and off the disk, and uses logic functions of
the graphics chip to convert entire tracks to and from MFM encoding. That's
how they get 11 sectors/track - the intersector gaps are tiny compared to
what a sector-oriented controller needs.
One consequence of this scheme is that when they wanted to go to 2MB
unformatted media (called "1.44MB" by PeeCee folks), they had two choices:
create a new sound chip that could handle double the data rate, or halve
the data rate of the floppy. They chose to monkey with the floppy. I have
several of these - when the drive indicates 2MB media, the motor spins at
half the rate so the sound chip can keep up. The upside of this is that
you can put one of these floppies on an older Amiga and it will still work.
The downside is that you can't steal a cheap/free drive from a PeeCee when
your Amiga HD floppy drive dies.
All of this aside, as flexible as the Amiga scheme is, there must be some
inherent limitations or there would be no need to design a Catweasel.
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 28-Jul-2004 04:20 Z
South Pole Station
PSC 468 Box 400 Temp -100. F (-73.5 C) Windchill -131.8 F (-91 C)
APO AP 96598 Wind 5.3 kts Grid 127 Barometer 673.6 mb (10868. ft)
Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html
28 Jul
28 Jul
3:46 a.m.
On Wed, 28 Jul 2004, Ethan Dicks wrote:
I don't recall either. For those that don't
know, the Amiga doesn't have
a traditional FDC chip - it uses a massive shift register in the sound chip
to clock pre-encoded data on and off the disk, and uses logic functions of
the graphics chip to convert entire tracks to and from MFM encoding. That's
how they get 11 sectors/track - the intersector gaps are tiny compared to
what a sector-oriented controller needs.
So what happens if you try to do disk access while displaying animations?
--
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