INTRODUCTION

This file describes how to modify a Mouse Systems M3 serial mouse
so that it will directly replace the normal Amiga mouse.  Although this
requires a little tinkering with the mouse, I think it is preferable because
it it TOTALLY compatible with ALL software and does not tie up a serial port.
Of course, I discovered this AFTER writing the OptMouse serial mouse program.

Ed Hanway
149 Arborwood Crescent
Rochester, NY 14615

BIX, GEnie, PLink: jehanway
Usenet: uunet!sisd!jeh or jeh@sisd.kodak.com

DISCLAIMER

I take no responsibility for any damage the following procedure may cause
to either the mouse or the computer.  The procedure will probably not work
for other Mouse Systems mice, and may not even work with all revisions of
the M3.  The risk is entirely yours.

Finally, don't get in over your head.  The procedure is simple enough that
you don't have to be a Ph.D., but if you've never used a soldering iron
before, find someone who has.

MODIFYING AN M3 SERIAL MOUSE TO WORK ON AN AMIGA

Inside my Mouse Systems M3 serial mouse, on the circuit board is a row of
10 holes with pin 1 closer to the center of the mouse. Wired as follows,
it works perfectly on my Amiga:

	Mouse	Amiga
	  1 ----- 9
	  2 ----- 5
	  3 ----- 6
	  4 ----- 1
	  5 ----- 3
	  6 ----- 4
	  7 ----- 8
	  8 ----- 7
	  9 ----- 2
	 10 NC	

All you need is a length of nine-conductor wire, a DB-9S connector, and
minimal soldering skills and you're set.

MODIFYING OTHER MICE

If you have the newer M4 model serial mouse, you're not so lucky.  The
convenient row of holes is missing and practically the entire circuit is
replaced by one custom chip.

It is still possible, although unlikely, that the proper signals exist
somewhere inside other mice, and if you probe around the innards of the
mouse with a voltmeter, you might find them.  Here's what you'll need to
hook up:

Amiga 
Pin # Description
----- -----------

1     V (Vertical Pulses)

2     H (Horizontal Pulses)

3     VQ (Vertical Quadrature Pulses)

4     HQ (Horizontal Quadrature Pulses)

	See below
	
5     UBUT* (Middle Button -- Optional)

	All buttons are active low.  When the switch is closed (button
	depressed) the signal should be grounded.
	
	The middle button can be left unconnected, but if you can find the
	signals for the other two buttons, you should be able to find this
	one, too.

6     LBUT* (Left Button)

	Active low.
	
7     +5V

	Power to the mouse from the Amiga.

8     GROUND

9     RBUT* (Right Button)

	Active low.
	
Identifying the movement pulses:

Once you identify the +5V and GROUND lines, you can hook them up and look for
candidates for the movement pulses. These are all logic-level signals (roughly
+5 or ground) that should flip back and forth as you move the mouse on its pad.

As you (very slowly) move the mouse to the RIGHT, you should see the following
pattern

     ____      ____      ____
H  _/    \____/    \____/    \____
        ____      ____      ____
HQ ____/    \____/    \____/    \____
   
When you move to the LEFT, you should see
     ____      ____      ____
H  _/    \____/    \____/    \____
   ____      ____      ____      __
HQ     \____/    \____/    \____/
   

Similarly,

DOWN:
     ____      ____      ____
V  _/    \____/    \____/    \____
        ____      ____      ____
VQ ____/    \____/    \____/    \____
   

UP:
     ____      ____      ____
V  _/    \____/    \____/    \____
   ____      ____      ____      __
VQ     \____/    \____/    \____/

(Info from the Amiga Hardware Reference Manual)

Notes:

Serial Mice that draw their power from the computer are often wired with a
three wire cable (+5V, GROUND, and the serial data).  This should help in
identifying +5V and GROUND  (they should be connected to thicker traces on
the mouse PC board).