New subject: Selenar Graphics II (Was: DECWriter II LA36 being given away)

11 Sep 2012

I was the one that was able to snag the LA-36 DECWriter II that Corey
Anderson had rescued from being scrapped.
Thanks, Corey, I really appreciate it!  I had a great time chatting
about the "old days" with Corey when I visited his home to pick up the
LA-36.  

I intend to use this as the console terminal for my PDP 11/34 system.
It's a lot more appropriate than the Heathkit H19 currently serving that
purpose.

I got the LA-36  home on Sunday, but didn't have time to do much with it
until yesterday.

I did a basic cleaning -- getting rid of dust and cobwebs.  In general
the terminal was in pretty good shape, and despite some dust and spider
leftovers, it was quite clean inside.

One of the first things I noticed was that the main controller board
looked different than I expected, and on closer inspection, I saw that
it wasn't a DEC board.  It said "SELANAR CORP." and "GRAPHICS II"
in
silkscreen on the board.

There are sockets for eight 2708 EPROMs, of which 6 are filled (I was
worried that some were missing because of the empty sockets), with round
stickers over the windows that say "SELANAR".   There are three sockets
for some kind of RAM (haven't identified it yet), of which only one
socket is filled.   There appear to be two processors, one made by
Western Digital, and another made by Fairchild.   Both appear to have
onboard EPROM, as they have windows on them that are painted over with a
thick black paint.

I checked all of the fuses, and they were good.  I unplugged everything
...
 from the control board (keyboard connector, printhead
drive, carriage drive stepper, pin-feed drive stepper), serial connector, and a
couple
of power connectors, and powered up the power supply, and found that all
of the voltages were good, with minimum ripple.  I did a close visual on
the controller board, and it looked good...no debris or signs of
overheating/blown components.  I also checked out the solenoid and
stepper driver board, and it also looked good.

I wiped down the carriage rail to remove dust and grime, and then oiled
it lightly.  The carriage moved smoothly in both directions, but the
ribbon advance mechanism seemed a bit gummed up, which I figured I could
address later, since the ribbon is all dried out anyway.  

I plugged all of the connectors back in, and put some paper in it, then
used a variac to slowly power it up. 
It didn't appear to like being slowly powered up, as the steppers got
all wonky - but, I didn't get any smoke, so I quickly ramped the power
back down, plugged the DECWriter directly into mains, and powered it up
with the power switch.  

The carriage went left until it hit the stop with a bang...and sat there
with the stepper humming for a nervous  3/4 or so second, then the
carriage moved to the right a bit, and things got quiet (other than the
hum of the power supply).  I set the machine to local mode, and hit a
key, and the pins hit the ribbon/paper, and the printhead moved to the
next print location.  After a familiar delay, the printhead moved to the
right to allow the character (which was invisible because of the bad
ribbon) to be seen.  I typed all of the characters on the keyboard, and
everything seems to work -- linefeed, carriage return, backspace, space,
repeat, bell(^G), etc.  So, the unit appears to be in good shape, though
I don't know if the characters print correctly until I can find a ribbon
for it.    

I'm quite happy that it seems to be  generally alive.

Now, on to the point of my posting:

Does anyone know anything about Selanar's Graphics II board for the
LA-36?  BitSavers doesn't have anything that I could find.  Google nets
old ads and product announcements in trade rags of the day (1982-ish).
Selanar also  made graphics engine boards for VT100's, Televideo 950's,
and various other printing and display terminals.  One advertisement I
saw showed an LA-36 that had a pretty printout of a Spirograph-like
drawing.  

I would love to find some documentation on how the graphics work.  I
found some information relating to FORTRAN libraries that provided
routines for "MOVE", "DRAW", and various other graphics primitives,
but
no real documentation.  I'd love to find an operator's guide or a
programming guide to figure out how to make the graphics work.  

I plan on pulling the ROMs and dumping them, and passing them to
BitSavers.  

Anyone out there have any information on this thing that they could
share?

I'm going to do some more cleanup, test the serial port to see if it
works, and track down a ribbon for it (I have  a lot of calculator
ribbons that I may put onto the spools for the DECWriter just as a
temporary measure).  The serial cable has had the connector cut off, so
I'll have to figure out the pinout and put a connector on the end.
Plenty of stuff to keep me busy.    There is a DB-25F connector on the
Selanar board that isn't plugged into anything.  I'm wondering what it
might be for, so I may hook a terminal up to it and see if I can get any
kind of response from it.  Hopefully someone out there will have some
docs for this thing that can eliminate the mysteries of this relic.

Thanks,

Rick Bensene