26 Jul
2012
26 Jul
'12
3:36 a.m.
Hi Everyone,
I'm thinking of a way to move as many of the PDP11 systems I have into
my attic office to a) get them going, and then b) run them
occasionally.
I've stripped the two low corporate racks to the chassis, and if I can
find a helping hand, I'm sure I can get them into the attic, then put
the tabletop of my electronics workbench on top of it (I'm a little
short on space). I'm thinking of bolting two pieces of rack profile to
one side of each rack, which would turn them into a single unit
comprising three racks. That way, I should be able to mount 6 10.5"
PDP's and 6 5.25" PDP's, and have them conveniently close to my
oscilloscope and logic analyzer to work on them.
Now for storage...
I have some RL02 drives, but I'm a bit reluctant to drag those
upstairs. I have Emulex scsi controllers for three of the PDP's (2 x
UC18, 1 x UC08), but the rest is without mass storage.
I read about the TU58 emulator that runs on Linux, and I'm thinking of
putting a DECserver into the rack with the PDP11's, and use virtual
TTY's on a Linux box that connect to the PDP11's over the DECserver,
then run multiple instances of the emulator so each PDP has one or
more emulated TU58's.
I know the "real" TU58 tapes can hold something like 256K of data. Are
the operating systems aware of this limit, or could you get by with
emulating a larger tape?
Thanks for any insight you may have to offer. Warnings like "That's a
really bad idea, because..." are also very welcome.
Cheers,
Camiel
26 Jul
26 Jul
4:13 a.m.
* On Thu, Jul 26, 2012 at 09:36:30AM +0200, Camiel Vanderhoeven <iamcamiel at
gmail.com> wrote:
I know the "real" TU58 tapes can hold
something like 256K of data. Are
the operating systems aware of this limit, or could you get by with
emulating a larger tape?
Hi Camiel,
Yes, what you want to do is totally possible. I just did something
similar a few days ago, so I'm happy to share what I learned about TU58
emulation with you. But first, be warned that as far as I know this only
works with XXDP and RT11.
I made use of two pieces of software.
1. tu58em v1.4e, available here in source form:
http://www.ak6dn.dyndns.org/PDP-11/TU58/tu58em/
NB: It did NOT compile out of the box on Ubuntu 12.04. I had
to edit the Makefile, and change line 22 from this:
$(CC) $(LFLAGS) -o $@ main.o tu58.o file.o serial.o
to this:
$(CC) -o $@ main.o tu58.o file.o serial.o $(LFLAGS)
and then it compiled fine.
2. The DOS RT11 image utilities available in a self-extracting archive
here:
http://www.fpns.net/willy/pdp11/rt11arc.exe
Documentation is available on the main page here:
http://www.fpns.net/willy/pdp11/tu58-emu.htm
Don't be alarmed - those DOS programs work just fine in Linux under the
'dosemu' environment. That's how I run them. It's not ideal, I wish
there were native Linux versions, but they do work.
The DOS programs are useful for manipulating RT11 images, and tu58em is
what actually serves the image.
If all you're doing is READING from the simulated tape, you can make the
image any size you want. RT11 only cares about the size of the TU58 when
writing to it. This is very useful.
If you do want to make a read/write tape, that second webpage
I linked to has two modified DD.SYS drivers, one for RT11 and one
for XXDP. They allow writing to large tape images if you want.
You can put them onto the tape image using the DOS tools.
For more information, I found this page helpful as well:
http://www.pdp11.co.uk/blog/2008/12/07/building-an-rt-11-tape-for-a-tu58-em…
I hope this helps you get started. If you have any questions I'll be
happy to try to answer. But yes, it does work! I just installed RT11 5.3
onto a virgin ESDI disk using an image I built in SIMH. I didn't have
any other way of getting it onto the PDP-11 except through tu58em.
-Seth
6:27 a.m.
On Thu, 26 Jul 2012 09:36:30 +0200
Camiel Vanderhoeven <iamcamiel at gmail.com> wrote:
I've stripped the two low corporate racks to the
chassis, and if
I can find a helping hand, I'm sure I can get them into the attic
Have a look
at the racks. Are the posts welded or is it riveted?
I had a similar problem with two DEC racks. I removed the rivets with a
drill and a chisel. There are only 28 of them. Then I put the parts
(the four posts, top and bottom) upstaris and put it back together with
M6 screws and hex-nuts. Easy to do, made transportation of the racks
much, much easier and the M6 screws hold it together just as well as
the rivets.
--
\end{Jochen}
\ref{http://www.unixag-kl.fh-kl.de/~jkunz/}
6:51 a.m.
On 7/26/12, Jochen Kunz <jkunz at unixag-kl.fh-kl.de> wrote:
On Thu, 26 Jul 2012 09:36:30 +0200
Camiel Vanderhoeven <iamcamiel at gmail.com> wrote:
They are riveted, so this would be feasible. It would make future
transportation easier too. Let me think about it...
I've stripped the two low corporate racks to
the chassis, and if
I can find a helping hand, I'm sure I can get them into the attic
Have a look
at the racks. Are the posts welded or is it riveted?
I had a similar problem with two DEC racks. I removed the rivets with a
drill and a chisel. There are only 28 of them. Then I put the parts
(the four posts, top and bottom) upstaris and put it back together with
M6 screws and hex-nuts. Easy to do, made transportation of the racks
much, much easier and the M6 screws hold it together just as well as
the rivets. 
8:27 a.m.
On 07/26/2012 03:36 AM, Camiel Vanderhoeven wrote:
er
I read about the TU58 emulator that runs on Linux, and I'm thinking of
putting a DECserver into the rack with the PDP11's, and use virtual
TTY's on a Linux box that connect to the PDP11's over the DECserver,
then run multiple instances of the emulator so each PDP has one or
more emulated TU58's.
I know the "real" TU58 tapes can hold something like 256K of data. Are
the operating systems aware of this limit, or could you get by with
emulating a larger tape?
Yes it has been done but you need to patch the driver.
I dont know if there was a easy way to do this.
The alternate is to make the device create multiple (up to two)
"drives".
Its a good idea. I have a product that was done maybe 15 years ago
by Bob (spare time gizmos) that emulated a tu58 using 512K of Ram
and a battery backup. Much faster as it didn't have the physical
access time limitations. (rewind or fast forward to block).
There are also software emulators of tu58 on the net that run on
PCs. That makes it easy to change "tapes".
Allison
4377
days inactive
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