PDP 11 Victory!

From: Vintage Computer Festival <vcf_at_siconic.com>
Date: Sat Feb 12 21:39:49 2005

Oh, I am stoked.

I just finished a day long saga of getting my PDP 11/23+ working with RX02
and TU-58 support.

I started out with where I left off a few days ago: I had a generic 11/23
system that was working quite well. It was booting off the RX02 drives
and I had RT11 up and running. Now I needed to get the DD module onto a
system disk so I could use the TU58 simulator so that I could then start
copying files from a bunch of disks to the PC.

The only problem was that the 11/23 only had one serial port. I couldn't
find my DLV-11J, which I apparently misplaced somewhere in the warehouse.
If I could only find it I'd have 4 serial ports. But it was nowhere to be
seen. So I re-grouped and decided, now that I pretty much know what I'm
doing, to go back to hacking on the 11/23+. It has a nice single board
CPU with 2 serial ports (one for console and one for TU58) and memory and
some various storage controllers. I really just needed to add RX02
controller and a bootstrapper, so I moved the appropriate boards from the
11/23. I hacked up a simple serial cable (just RX and TX) and was able to
get an ODT prompt. Sweet. So I configured the 11/23+ CPU properly and
had it coming up in the boot monitor.

Now I just needed to be able to boot from the TU58 simulated drive. I
futzed around with a laptop to use as my console so I could make the PC
(my main data conversion station) be the TU58 drive. The laptop ended up
having a messed up serial port: I just couldn't get it to send/receive
characters properly. I've never seen anything like it. Weird. So
anyway, I ditched that and pulled out a VT510 I had handy and used that as
the console (which was more appropriate anyway). So far so good.

I tested the serial port between the PC and the second serial port on the
11/23+ CPU. I restarted the PDP-11 and specified DD as the boot device
and it then went searching. On the PC side (in Procomm) I issued a break
and the PDP 11 crashed. Good sign: the signals are all apparently there.

Howard Harte hooked me up with a CD with everything I needed on it. I had
the TU58 simulator plus a bunch of boot images to choose from. I used
John Wilson's *EXCELLENT* PUTR utility and found the right boot image
(with DY and DD drivers, plus PIP, etc.)

So I downloaded all the necessary files into the PC and got the TU58
simulator up and running. I restarted, entered DD at the boot prompt, and
all of a sudden the TU58 simulator sprang into life and within a few
seconds I was at an RT11 prompt!! Totally cool. My arms sprang up in
victory for this round.

So now I needed to initialize a system disk. The TU58 is just too slow to
run from, even at 19.2Kbps (fortunately, the 11/23+ serial ports can go up
to 19,200, so at least data transfer will be twice as fast as I was used
to). I had the disk controller manual handy and typed in the commands to
format a blank disk (really poking bytes into the appropriate registers).
After a couple minutes the disk was formatted.

I rebooted from the DD drive and issued the appropriate commands to
initalize the disk, then copied all the system files over. Finally, the
last step was to write the boot monitor to the disk. The disk controller
manual explained how to do it but something was confounding me: they were
putting a space between the device name and the boot monitor filename in
the example. Once I understood this, I did a COPY/BOOT using the RT11SJ
file on the existing bootable RT-11 disk I have and it took (COPY/BOOT
DY1:RT11SJ DY0: for posterity).

I restarted, specified DY, and lo and behold, RT-11 booted off the floppy!
Woohoo!! This is so gawd damn cool! My arms were flung up in a final
private display of victory.

So now I finally have a fully working PDP-11 with DD support. I can now
finally copy the files off this batch of disks I have and then use PUTR
(*brilliant* program) to move them out of the images into individual PC
files and I'm set.

I really have to thank Megan for her indespensible PDP-11 field guide
which helped to identify all the various boards I dug through looking for
what I needed. And the Will's Works RT11 DD Radial Serial Protocol Server
(TU58 emulator) and John Wilson's PUTR program make this all so damn

Also, thanks again to everyone on the list who helped with the debugging
and such! As a reward, the first disk I dump will be the one with Super
Star Trek on it ;)

I hope I can be of assistance to other people in the future who try to get
their Qbus PDP-11 systems running. I learned a lot from this project.

I love PDP-11's!!!

Next projects:

- find a SCSI card so I can hook up SCSI devices (ZIP drive)
- Hook up some other drives (RK, RL) and play around with them
- Get my 11/34 up and running which has RK05 and RK05F drives in the rack
and is otherwise a very complete system with 16 serial ports (PDP-11
hacking party anyone? ;)

Sellam Ismail                                        Vintage Computer Festival
International Man of Intrigue and Danger                http://www.vintage.org
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Received on Sat Feb 12 2005 - 21:39:49 GMT

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