[SunRescue] Sun mouse upgrades, or, cheap thrills with a soldering iron

[James Lockwood]

Ok, so this isn't exactly Sun "rescue", but I thought it would be
interesting to some of the readers here.

Sun mice are both good and bad.  Good, because they're generally very well
made and have an excellent feel (I prefer the opticals myself).  Bad,
because they run at a slow serial speed (1200bps).  This makes mouse
movement somewhat "jumpy".

Due to the way that mouse movement is encoded on a Sun, you can only get a
maximum of 24 positional or button updates per second.  This doesn't
sound so bad until you realize that you are getting a new position less
than half as often as you are updating the screen, and you are looking at
a minimum of 40ms latency for any mouse action at all.  Move nearly any
Sun mouse rapidly from side to side, and you get a very jumpy response.
The same problem is noticeable to a lesser degree when scrolling or moving
windows.

The good news is that Sun, in their considerable foresight, made it
possible for all type-5 mice to run at a faster serial speed (4800bps). 
This gives you 96 updates per second with 10ms latency which gives a much
better mouse feel (and better performance from interactive RT processes
such as 3D visualization or games).  You need Solaris 2.3 or above to take
advantage of faster mice speeds.

Anyways, here's a brief guide to "upgrading" your Sun type-5 mouse.  No
warranty expressed or implied, if you screw up and toast your
E6500/Elite3D that you're using for 3D visualization of weather data I
will disavow all knowledge of this message.  This post will self-destruct
in 5 seconds... 

Anyways, there are two different versions of the type-5 mouse.  I'll
discuss the ball mice (optomechanicals) first:

If you've got a mouse that's part number 370-1586-01, congratulations! 
You have an extremely rare piece of Sun history, that will doubtless be
worth as much as $15 in another decade.  These were the only 4800bps mice
produced by Sun (for the Voyager).  Lord only knows what they were
thinking at the time. 

Part numbers 370-1586-02 and -03 are the most common versions.  These are
fairly easy to modify as follows:

Remove the mouse ball.  Disassemble the mouse by removing the 3 bottom
screws and remove the top cover.  Unplug the circuit board from the cable
and flip the board over.

Using either a soldering iron or a pair of cutters, remove the zero-ohm
resistor at "R3" (near the mouse ball).  Connect the solder pads at "R2"
(in one corner of the board) using either a blob of solder or a wire
whisker.  If the jumper at "W9" (next to R2) is missing (usually is on -03
mice, isn't on -02 mice), short that one as well (you can't just use a
blob of solder here as another wire runs between the terminals). 
Installation is the reverse of removal. 

For opticals (370-1398 tested, no idea on any other):

Remove the felt pads on the bottom, exposing the screws and plastic tabs
at the top.  Remove the screws and pop the tabs out using a flat-bladed
screwdriver.  Remove the top cover.  _Gently_ unplug the circuit board
from the flex-cable that runs to the optics, I find that a pair of
non-crushing needle-nose pliers and a lot of patience is good here.
Extract the board and flip it upside-down (but don't disconnect the cable
that comes out of the mouse, it's a pain to get back on right).

Join the solder pads at one corner near the main chip labeled "JP2" with a
small wire.  Reassemble, being careful to get the flex-cable back in all
the way without breaking it.

This is it.  Plug it in and move the mouse around.  Pretty smooth, eh?  To
confirm that you are running at 4800bps, run: 

% stty </dev/mouse
speed 4800 baud; -parity 
...

I hope this helps people, it's a cheap upgrade that makes a terrific
improvement.  Once you've done it, it's hard to go back.  Takes me an
entire minute to do including disassembly and reassembly now (all my
friends made me modify their mice as soon as I let them know).  If anyone
out there is solder-phobic but would like to have one of these let me
know, maybe those of us who aren't can do it as a public service.  If you
ever come across a mouse with "4800" written on the bottom of it in black
marker, you've found one of mine.  :-)

-James