Care and feeding of some Lisp machines (TI Explorer and Xerox Star)

[Josh Dersch]

On Mon, Sep 14, 2020 at 6:35 AM Michael Engel via cctech <
cctech at classiccmp.org> wrote:

> Hi,
>
> for a planned exhibition, I am thinking of restoring two of the machines
> to working state again that are in storage here for decades:
>
> - A TI Explorer ("Sperry" labeled)
> and
> - A Xerox Star (no idea if ours actually ran Interlisp or one of the
> other OSes for the Star/Dandelion)
>
> There is "sen´s dandelion restoration blog" at http://dandelion.sen.cx/
> (which seems to be very helpful to test the power supply) and, of
> course, lots of documents and software on bitsavers. I have quite a bit
> of experience with TI1500 machines, so the Explorer feels rather
> familiar, but I have never worked with Xerox machines before.
>
> Before I start to disassemble and test the machines, I would be
> interested to hear about specific problems you might have experienced
> bringing up one of these two machines, preferably those on the
> unexpected side.
>
> Some things I could not find so far are the mouse and the console cable
> for the Explorer. It seems that the mouse is related to MouseSystems
> optical mice used on older Sun/SGI systems (but the interface might be
> different?). The fiber optics cable for the display (TI part number
> 2233200 according to the field service manual) might be another problem
> - if you know any details about this, I would be very interested...
>
> Another thing that is also missing is the mouse pad for the three button
> optical Xerox mouse. Is it possible that an optical mouse pad for
> Sun/SGI machines is compatible?
>
> Best wishes,
>      Michael
>
>
I've restored a Star/1108 (and wrote a Star emulator) and am in the middle
of an Explorer restoration, I'm happy to help out where I can.

I'd recommend picking up an MFM Emulator (https://www.pdp8.net/mfm/mfm.shtml)
along with the SA1000 adapter for same, for use with the Star.  The
original disks are getting more difficult to keep running, and it's also a
lot more convenient for switching between different operating systems, etc.

Remove the sound-deadening foam from the panels of the system, it's getting
crumbly and isn't going to do you any favors to leave it in place.  I've
found the power supplies to be fairly reliable.  One issue is weak picture
tubes in the displays -- the monitors are powered on with the system and
have no separate off switch, so they tended to get a lot of hours put on
them.  We had good luck with a tube rejuvenator on the one we restored at
LCM.

The Star mouse pad can be recreated with a laser printer (I've used this:
http://www.digibarn.com/collections/devices/xerox-mousepad/index.html, and
there's a postscript file floating around out there...).  Or any surface
with a fine pattern on it seems to work pretty well; I was able to make it
work on a speckled countertop and the pant leg of my jeans at one point.
It's a lot more forgiving than the Sun mice which need the fixed grid of
the metal mouse pads.

For the Explorer, there are a number of r fa line filter caps in the
system, on the power supply board as well as on a separate board near the
rear of the chassis.  I suggest replacing these immediately as they like to
let out smoke.  The optical cable is extremely rare and despite some
valiant efforts we haven't found an equivalent, or new-old-stock
replacements.  A friend of mine is working on retrofitting modern optics,
and has made some great progress.  The mouse is indeed a standard Mouse
Systems, I'm missing mine at the moment and haven't yet gotten to the point
of adapting a mouse to replace it.  I suspect it's equivalent to the M2
used on the Sun-2 and LMI Lambda systems.

Media for the Explorer is another question that I'm hoping to answer soon.
There are disk images from the Meroko emulator but my understanding is that
they are incomplete.  Bitsavers has QIC tape images but I have yet to try
them.  The interface on the Explorer is SCSI but I haven't had luck booting
it from a SCSI2SD w/Meroko images loaded.  The disk boxes contain an Emulex
SCSI->MFM bridge, so use of Dave's MFM emulator might make sense here as
well.

If you have disks in your Explorer, let me know -- capturing an image of
their contents would be extremely useful, and the original Maxtor drives
are not long for this world.

Hope that helps a bit, happy to answer any questions... or try anyway.
- Josh