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

Michael Engel engel at
Mon Sep 14 14:39:08 CDT 2020


thanks Ian - I think I found the pinout, it was hidden in TI's Display Unit General Description 
(, Fig. 4-6 - not in the 
Field Service Manual where I expected it...

The mouse has a simple quadrature-encoded output (like Atari ST/Amiga mice) on a 9-pin 
SUB-D style connector. Of course, the pinout is different, for the Explorer it is:

1 - +5V DC 250mA
2 - XA
3 - XB
4 - YA
5 - YB
6 - left key (CLKEY-) - so active low buttons, I assume
7 - middle key (CMKEY-)
8 - right key (CRKEY-)
9 - signal/power ground

So it should be easy to build one in case I can't find the original one. It seems that there was
also a later non-optical mouse version that looked similar to early Genius PC mice.

-- Michael

> On 14 Sep 2020, at 20:34, null <ian.finder at> wrote:
> Regarding the mouse- it is a black Mouse Systems optical mouse, terminated in a two row IDC connector.
> If desired, I can take internal pictures and send along the pinout. Let me know.
>> On Sep 14, 2020, at 09:01, Josh Dersch via cctech <cctech at> wrote:
>> On Mon, Sep 14, 2020 at 6:35 AM Michael Engel via cctech <
>> cctech at> 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
>>> (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 (
>> 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:
>>, 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

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