Need RL02 Controller for PDP-11/44 Restoration - test-drb@ccmp.vtda.org

26 Jan 2011

On 01/26/11 19:00, Ethan Dicks<ethan.dicks at gmail.com> wrote:

...
  On Tue, Jan 25, 2011 at 9:23 PM, Michael Thompson
 <michael.99.thompson at gmail.com>  wrote:
  >  I am reassembling a PDP-11/44 from parts
for the Rhode Island Computer...
 >
 >  The RA81s won't spin up, so I suspect that I need to replace the
 >  starting capacitors.  I read through the blog - if the motors start spinning
as you describe
 (I envision you mean for a few seconds; please correct me if this is
 wrong)_then_  the drive stops spinning, I doubt it's the capacitors.
 If the motors_don't_  start moving when you put the drive online, then
 that is one component to examine. 
Nit pick: The online operation is the "A" and "B" buttons. The
"RUN" 
button is for spinning the drive up. It can be spinning and offline. :-)

...
  RA81s were at one point, exceedingly susceptible to
HDA failure.  I
 don't recall the specific ECO levels, but some version after "E" used
 a different glue than its predecessors leading to particulate
 contamination leading to catastrophic failure.  ISTR looking for "H2"
 or "K2" drives after that disaster. 
Yes. But I think even with the bad glue, the disk do spin up more than a 
couple of seconds.

...
  RA81 drives have a DB25 inside.  You can plug a
terminal in and run
 on-board diagnostics and monitor operations.  You can run with the lid
 up or lid down (snaking a ribbon cable out of the drive).  The molex
 connector next to the data connector is to power a small hand-held LED
 terminal (I saw one once, used with a high voltage chassis for
 particle physics, but the terminal was the same). 
Good suggestion. The terminal should be at 300 bps, if I remember right. 
8N1. And data leads only is enough.

...
  Try plugging in a working VT220 and letting the drive
tell you what it
 thinks is going on.  You might find that it's starting to spin up then
 not liking what it sees and spinning down.

 Oh... just a detail - you mention locked heads - you_did_  pull the
 cord to retension the drive belt, right?  (for safe transport, the
 RA81 has you locking the heads_and_  disengaging the motor from the
 HDA by removing belt tension).  If you didn't do this step, what I
 think may happen is the onboard processor will start to spin the
 motor, sense no rotation from the HDA, then spin the motor down and
 emit a fault code.  Maybe this is what you are seeing? 
That was a very good suggestion. The belt can be disengaged in two ways, 
depending on the version of the drive. Either a cord, or else a lever on 
the inside of the outer wall.
It should be pretty obvious when you know what you are looking for, though.

With these suggestions, as well as the power control bus to check, the 
drives should be possible to get running... :-)

...
   > 
https://sites.google.com/site/ricmwarehouse/Home/equipment/dec-pdp-1144  Reading
through your blog, I don't think you will have success with
 booting 2.11BSD on your 11/44 with a TU81+ unless you have install
 media that knows about that tape controller.  The 2.9BSD tapes I have
 require an "MS" device (older OSes might or might not require an
"MT"
 device).  Back in the day, there were several incompatible tape
 controller types, with different boot ROMs, and your install media had
 to match your controller and ROMs (or you had to toggle in the
 bootstrap).  You can install 2.11BSD using vtserver and a virtual tape
 drive though.  Also, if you do get real 2.11BSD install tapes, you'd
 probably want to be looking for a TU80 and, IIRC, an M7454 controller
 card. 
2.11 will install fine from a TU81. The biggest problem is finding 
booting roms for the TU81. TU81 is TMSCP, works the same as TK50.

	Johnny