Please consider a donation to the Higher Intellect project. See or the Donate to Higher Intellect page for more info.

3 Button Serial Mouse mini-HOWTO Linux

From Higher Intellect Vintage Wiki
Jump to navigation Jump to search
  The 3 Button Serial Mouse mini-HOWTO
  Geoff Short, [email protected]
  v1.33, 31 May 1998

  How to get a 3 button serial mouse working properly under Linux.

  Table of Contents

  1. Disclaimer

  2. Introduction

  3. Serial Ports

  4. Switched Mice

  5. Normal Mice

  6. Switching a Mouse to 3-Button Mode

  7. Wheeled mice

  8. Using gpm to Switch Mouse Modes

  9. Using two mice

  10. XF86Config and Xconfig file examples

  11. Cables, extensions and adaptors

  12. Miscellaneous Problems and Setups

  13. Models Tested

  14. Further Information

  15. Mouse Tail


  1.  Disclaimer

  The following document is offered in good faith as comprising only
  safe programming and procedures. No responsibility is accepted by the
  author for any loss or damage caused in any way to any person or
  equipment, as a direct or indirect consequence of following these

  2.  Introduction

  The most recent version of this document can always be found at

  There is a Japanese translation at
  ftp/euc/3-Button-Mouse.euc; and a French one at  Other
  translations may be available - check your local LDP mirrors.

  Most X applications are written with the assumption that the user will
  be working with a 3 button mouse.  Serial mice are commonly used on
  computers and are cheap to buy.  Many of these mice have 3 buttons and
  claim to use the Microsoft protocol, which in theory means they are
  ideal for the X windows setup.  (The record for the cheapest working 3
  button mouse currently stands at $1.14!)

  Most dual-protocol mice will work in two modes:

  ·  2-button Microsoft mode.

  ·  3-button MouseSystems mode.

     This document leads you through the different steps needed to
     configure your mouse in these two different modes, especially the
     steps needed to use the more useful 3-button mode.

  As distributions become easier to set up, some of the problems ought
  to go away.  For instance, RedHat have a mouseconfig program to set
  things up for you.  However, some versions of RH5.0 had a bug in
  mouseconfig, so make sure you check for patches.

  3.  Serial Ports

  The first thing to do is to make sure the software can find the mouse.
  Work out which serial port your mouse is connected to - usually this
  will be /dev/ttyS0 (COM1 under DOS) or /dev/ttyS1 (COM2). (ttyS0 is
  usually the 9 pin socket, ttyS1 the 25 pin socket, but of course there
  is no hard and fast rule about these things.)  There are also an
  equivalent number of /dev/cua devices, which are almost the same as
  the ttyS ones, but their use is now discouraged.  For convenience make
  a new link /dev/mouse pointing at this port.  For instance, for ttyS0:

       ln -s /dev/ttyS0 /dev/mouse

  4.  Switched Mice

  Some mice, not usually the cheapest ones, have a switch on the bottom
  marked `2/3'. Sometimes this may be `PC/MS'. In this case the `2'
  setting is for 2 button Microsoft mode, and the `3' for 3 button
  MouseSystems mode. The `PC/MS' switch is a bit more complicated.  You
  will probably find the `MS' setting is for Microsoft, and the `PC' is
  for MouseSystems. You may find the `PC' setting described as ps/2
  mode, but it should do MouseSystems as well.  If you have such a
  mouse, you can switch the switch to `3' or `PC', put the MouseSystems
  settings in your XConfigs (see below) and the mouse should work
  perfectly in 3-button mode.

  5.  Normal Mice

  If you don't have any switches, and no instructions, then a little bit
  of experimentation is needed.  The first thing to try is to assume the
  mouse maker is telling the truth, and the mouse is full Microsoft. Set
  up your Xconfigs to expect a Microsoft mouse (see the Xconfig section)
  and give it a try.

  If the mouse didn't work at all, then you don't have a Microsoft
  mouse, or there is some other problem. Try the other protocols in the
  configs, the man page for the config file is the best place to start
  looking. Also look in the Miscellaneous Problems section below.

  What you will probably find is that when you run X, the mouse works
  fine but only the outer two buttons do anything.  You can of course
  accept this, and emulate the third button (press both buttons at once
  to click the middle one) like you do with a two button mouse. To do
  this, change your Xconfig file as shown in the Xconfig example section
  below.  This may mean you have bought a 3 button mouse for no good
  reason, and you are certainly no further forward. So, now you need to
  look at your hardware.

  6.  Switching a Mouse to 3-Button Mode

  Even cheap mice can also work under the Mouse Systems protocol, with
  all three buttons working.  The trick is to get the mouse to think
  it's a Mouse Systems one, something you rarely see in your

  ·  Before you power up your computer, hold down the left mouse button
     (and keep it held down until it has booted to be on the safe side).

  When the mouse first gets power, if the left button is held down it
  switches into Mouse Systems mode. A simple fact, but not always
  publicised. Note that a soft reboot of your computer may not cut the
  mouse power and therefore may not work. There are a number of other
  ways of switching the mode, which may or may not work with your
  particular mouse. Some of these are less drastic than rebooting your
  computer, two are more so!

  ·  If your computer is get-at-able you can unplug the mouse and plug
     it back in with the button held down (although you shouldn't
     normally plug things in to a live computer, the RS232 spec says it
     is OK).

  ·  You may be able to reset the mouse by typing echo "*n" >
     /dev/mouse, which should have the same effect as unplugging it.
     Hold the left button down for Mouse Systems mode, not for
     Microsoft. You could put this in whatever script you use to start X

  ·  Bob Nichols ([email protected]) has written a small c
     program to do the same thing, which may work if echo "*n" does not
     (and vice versa). You can find a copy of his source code at

  ·  Someone has reported that the `ClearDTR' line in the Xconfig is
     enough to switch their mouse into Mouse Systems mode.

  ·  If you are brave enough, open the mouse up (remember that this will
     invalidate your warranty) and have a look inside. In some cases,
     the mouse may have a switch inside, for some strange reason known
     only to the manufacturer. More likely on the cheap mice is a jumper
     which you can move. The switch or jumper may have the same effect
     as a `MS/PC' switch described in the ``Switched Mice section''
     above.  You may find that the circuit board is designed for a
     switch between 2 & 3 buttons, but it hasn't been fitted. It will
     look something like:

          | o | o | o |  SW1
            1   2   3

  Try linking pins 1-2 or 2-3, and see if it changes the behaviour of
  the mouse.  If it does, you can either fit a small switch, or solder
  across the contacts for a quick and permanent solution.

  ·  Another soldering solution which might be a last-resort for mice
     which don't understand MouseSystems at all, from Peter Benie
     ([email protected]).  If the middle button's switch is
     double-pole, connect one side of the switch to the left button's
     switch, and the other side to right button's switch.  If it's not a
     double pole switch then use diodes rather than wire.  Now, the
     middle button pushes the left and right buttons down together.
     Select ChordMiddle in the XF86Config and you have a working middle

  ·  The ultimate recourse with the soldering iron was first described
     to me by Brian Craft ([email protected]). Two common
     generic mouse chips are the 16 pin Z8350, and the 18 pin HM8350A.
     On each of these chips, one pin controls the mode of the chip, as

       Pin 3   Mode
       -----   ----
       Open    Default Microsoft. Mouse Systems if a button is held on power-up.
       GND     Always Mouse Systems.
       Vdd     Always Microsoft.

  (Pins are numbered as follows:)

       pin1  -| \/ |-
       pin2  -|    |-
       pin3  -|    |-
             -|    |-
             -|    |-
             -|    |-
             -|    |-
       pin8  -|____|-

  (This info comes courtesy of Hans-Christoph Wirth, and Juergen Exner,
  who posted it to de.comp.os.linux.hardware)  You can solder a link
  between pin 3 and gnd, which will fix the mouse into MouseSystems

  ·  Peter Fredriksson ([email protected]) has tried the SYSGRATION
     SYS2005 chip, and found that linking Pin 3 to Gnd forced Mouse
     System mode.

  ·  Uli Drescher ([email protected]) confirms it works on an HN8348A
     chip; Ben Ketcham ([email protected]) confirms the
     HM8348A (Pin 9 is Gnd).

  ·  Urban Widmark ([email protected]) says the same applies to the
     EC3567A1 chip, where Pin 8 is ground.  I've tried it as well and it
     works fine.

  ·  Timo T Metsala ([email protected]) has found that on the
     HT6510A chip pin 3 is mode select, pin 9 is Gnd.  The same works
     for the HT6513A chip.  Holtek also make HT6513B and HT6513F chips -
     on these, pin 8 is Gnd.

  ·  Robert Romanowski ([email protected]) says pin 3 - pin 8 (Gnd)
     works on an EM83701BP chip too.

  ·  Robert Kaiser ([email protected]) confirms that pin 3 - Gnd works on
     a EC3576A1 chip too.

  ·  Sean Cross ([email protected]) found it was pin 2 - pin 7 (Gnd)
     on a HM8370GP chip.

  ·  Peter Fox ([email protected]) used pin 3 - pin 8 on a
     HM8348A chip.

  ·  Jon Klein ([email protected]) found pin 3 - pin 9 did the
     trick for a UA5212S chip.

  ·  As an alternative to the above soldering methods, you can get the
     mouse to hold it's own button down when booting:  this circuit from
     Mathias Katzer.

             ---  R  ---------O------ + Supply
            |   -----   |        |                     C = 100nF capacitor
            |           | E      |                     R = 100kOhm
            |       __ /         |                     T = BC557 transistor
            |      /  \          O
            |   B | #V | T         /
            |-----|-#  |          /   Left button switch of the mouse
            |     | #\ |         O
            |      \__/          |
           ---         \  C      |
           --- C        ------O----------> (to somewhere deep inside the mouse)
           ###  Ground

  The test mouse was a no-name model MUS2S - whether this works in other
  mice depends on the circuit of the mouse; if the switch is connected
  to ground and not to +Supply, an npn-transistor like the BC547 should
  work; R and C have to be swapped then, too.

  So there you have it, the choice is yours. Stick with the default
  Microsoft two buttons, or work out how to switch the mode and set X up
  to take advantage of this.

  7.  Wheeled mice

  Mice with wheels have emerged in the last few years, starting with the
  Microsoft Intellimouse and spreading to other manufacturers.  The
  wheel can be clicked like a button, or rolled up and down.  Far and
  away the best reference for information is which describes
  how to get lots of X applications to recognise the scrolling action.

  In general, you'll need a fairly new Xserver to use the scrolling
  action, but some older servers will recognise the clicking actions.
  For instance, the Intellimouse is supported by XFree 3.3.1 and later.

  8.  Using gpm to Switch Mouse Modes

  gpm is the program that lets you use the mouse in console mode.  It is
  usually included in linux distributions, and can be started from the
  command line or in the startup script /etc/rc.d/rc.local.  Note that
  distributions don't always have the most recent version (1.13 at time
  of writing) which can be found on mirrors of

  The main modes for serial mice under gpm are:

       gpm -t ms
       gpm -t msc
       gpm -t help

  for Microsoft or MouseSystems modes, or to probe the mouse for you and
  tell you what it found.  To run gpm in MouseSystems mode, you may need
  a -3 flag, and possibly a DTR option, using the -o dtr flag:

       gpm -3 -o dtr -t msc

  gpm is often able to recognise all three buttons of the mouse even in
  Microsoft mode.  And newer versions (Version 1.0 and later (?))  can
  then make this information available to other programs.  For this to
  work, you need to run gpm with the -R tag, like this:

       gpm -R -t ms

  This will make gpm re-export the mouse data to a new device, called
  /dev/gpmdata, which looks like a mouse to any other program.  Note
  that this device always uses the MouseSystems protocol.  You can then
  set your Xconfig to use this instead of /dev/mouse as shown below, but
  of course you must ensure gpm is always running when you use X.  Some
  people have reported that some middle-button events are not correctly
  interpreted by X using this technique, this may be down to an individ­
  ual mouse setup.

  Changing button mapping for gpm and X ([email protected])

  You may find that gpm uses different default button mappings to X, so
  using both systems on the same machine can be confusing.  To make X
  use the same buttons for select and paste operations as gpm, use the X

       xmodmap -e "pointer = 1 3 2"

  which causes the left button to select and the right button to paste,
  for either 2-button or 3-button mice.  To force gpm to use the X stan­
  dard button mapping, start it with a -B command, eg:

       gpm -t msc -B 132

  9.  Using two mice

  In some cases, for instance a laptop with a built-in pointing device,
  you may wish to use a serial mouse as a second device.  In most cases
  the built-in device uses the PS/2 protocol, and can be ignored if you
  don't wish to use it.  Simply configure gpm or X to use /dev/ttyS0 (or
  whatever) as usual.

  To use both at once, you can use gpm -M to re-export the devices.
  More details in the gpm man page.  Also, XFree 3.3.1 and later support
  muliple input devices, using the XInput mechanism.  Auto-generated
  XF86Config files should have the necessary comments in them.

  10.  XF86Config and Xconfig file examples

  The location of your configuration file for X depends on the
  particular release and distribution you have. It will probably be
  either /etc/Xconfig, /etc/XF86Config or /usr/X11/lib/X11/XF86Config.
  You should see which one it is when you start X - it will be echoed to
  the screen before all the options are displayed. The syntax is
  slightly different between the XF86Config and Xconfig files, so both
  are given.

  Microsoft Serial Mouse

  ·  XF86config:

       Section "Pointer"
           Protocol "microsoft"
           Device "/dev/mouse"

  ·  Xconfig:

       # Mouse definition and related parameters
       Microsoft      "/dev/mouse"

  Microsoft Serial Mouse with Three Button Emulation

  ·  XF86config:

       Section "Pointer"
           Protocol "microsoft"
           Device "/dev/mouse"

  ·  Xconfig:

       # Mouse definition and related parameters
       Microsoft      "/dev/mouse"

  MouseSystems Three Button Serial Mouse

  ·  XF86config:

       Section "Pointer"
           Protocol "mousesystems"
           Device "/dev/mouse"
           ClearDTR            #  These two lines probably won't be needed,
           ClearRTS            #  try without first and then just the DTR

  ·  Xconfig:

       # Mouse definition and related parameters
       MouseSystems    "/dev/mouse"
       ClearDTR                #  These two lines probably won't be needed,
       ClearRTS                #  try without first and then just the DTR

  Microsoft Serial Mouse with gpm -R

  ·  XF86config:

  Section "Pointer"
      Protocol "MouseSystems"
      Device "/dev/gpmdata"

  ·  Xconfig:

       # Mouse definition and related parameters
       MouseSystems      "/dev/gpmdata"

  11.  Cables, extensions and adaptors

  The only wires needed in a mouse cable are as follows: TxD and RxD for
  data transfer, RTS and/or DTR for power sources, and ground.
  Translated into pin numbers, they are:

                   9-pin port     25-pin port
               TxD     3                2
               RxD     2                3
               RTS     7                4
               DTR     4               20
               Gnd     5                7

  The above table may be of use if you wish to make adaptors between 9-
  and 25-pin plugs, or extension cables.

  12.  Miscellaneous Problems and Setups

  ·  If you have trouble with your mouse in X or console mode, check you
     are not running a getty on the serial line, or anything else such
     as a modem for that matter. Also check for IRQ conflicts.

  ·  It is possible that you need to hold down the left button when
     booting X windows.  Some systems may send some sort of signal or
     spike to the mouse when X starts.

  ·  Problems with serial devices may be due to the serial port not
     being initialised correctly at boot. This is done by the setserial
     command, run from the start-up script /etc/rc.d/rc.serial. Check
     the man page for setserial and the Serial-HOWTO for more details.
     It may be worth a little experimentation with types, for instance
     try setserial /dev/mouse uart 16550 or 16550a regardless of what
     port you actually have.  (For instance, mice don't like the

  ·  The ClearDTR flag may not work properly on some systems, unless you
     disable the RTS/CTS handshaking with the command:

  stty -crtscts < /dev/mouse

  (Tested on UART 16450/Pentium by Vladimir Geogjaev geog­
  [email protected])

  ·  Logitech mice may require the line ChordMiddle to enable the middle
     of the three buttons to work. This line replaces Emulate3Buttons or
     goes after the /dev/mouse line in the config file. You may well
     need the ClearDTR and ClearRTS lines in your Xconfig.  Some
     Logitech mice positively do not need the ChordMiddle line - one
     symptom of this problem is that menus seem to move with the mouse
     instead of scrolling down. (From: [email protected])

  ·  Swapping buttons: use the xmodmap command to change which physical
     button registers as each mouse click. eg:  xmodmap -e "pointer = 3
     2 1"  will turn round the buttons for use in the left hand. If you
     only have a two-button mouse then it's just numbers 1 & 2.

  ·  Acceleration: use the xset m command to change the mouse settings.
     eg xset m 2  will set the acceleration to 2. Look at the manpage
     for full details.

  ·  Pointer offset: If the click action appears to be coming from the
     left or right of where the cursor is, it may be that your screen is
     not aligned. This is a problem with the S3 driver, which you may be
     able to fix using xvidtune. Try Invert_VCLK/InvertVCLK, or EarlySC.
     This info from Bill Lavender ([email protected]) and Simon Hargrave.
     In the XF86Config, it might look like this:

       Subsection "Display"
           Modes       "1024x768" "800x600" "640x480" "1280x1024"
           Invert_VCLK "*" 1

  ·  If you are getting `bouncing' of the mouse buttons, ie two clicks
     when you only wanted one, there may be something wrong with the
     mouse.  This problem has been solved for Logitech mice by Bob
     Nichols ([email protected]) and involves soldering some
     resistors and a chip in the mouse to debounce the microswitches.

  ·  If some users cannot get the mouse to work but some (eg root) can,
     it is possible that the users are not running exactly the same
     thing - for instance a different version of X or a different
     Xconfig.  Check the X start-up messages carefully to make sure.

  ·  If you find the mouse pointer is erasing things from your screen,
     you have a server config problem.  Try adding the option linear, or
     maybe nolinear to the graphics card section, or if it is a PCI
     board, the options tgui_pci_write_off and tgui_pci_read_off.  (This
     seems to be a Trident Card problem.)

  ·  If the mouse cursor doesn't show up on the screen, but otherwise
     seems to be working, try the option "sw_cursor" in the Device
     section of the config file.

  ·  If your mouse stops working when its sunny or when you turn a light
     on, it may be that the sensors are being swamped by light getting
     through the case.  You could try painting the inside of the case
     black, or putting some card in the top.

  ·  Microsoft Brand mice are often a cause of problems. The newest
     ``Microsoft Serial Mouse 2.1A'' has been reported not to work on
     many systems, although unplugging it and plugging it in again may
     help.  gpm version 1.13 and higher should also support 2.1A mice,
     using the pnp mouse type.  (See the gpm section for how to re-
     export this.)  The ``Microsoft Intellimouse'' also causes problems,
     although it should now be supported by XFree version 3.3 and later.

  13.  Models Tested

  There are a lot of different mice out there, and I cannot honestly say
  that you should go out and buy one rather than the other. What I can
  do is give a list of what I think these mice do, based on experience
  and heresay.  Even with this information you should be a little
  cautious - we had two identical mice in our office on two computers,
  some things worked on one and not t'other!  Any additions to this list
  would be welcome.

  Mouse Systems optical mouse, serial version
  Works well (as you might expect from the name!) without ClearDTR or
  ClearRTS in the config.
  WiN mouse, as sold by Office World for eight quid.
  Standard dual-mode Microsoft/MouseSystems.
  Agiler Mouse 2900
  Standard dual-mode Microsoft/MouseSystems. SYSGRATION SYS2005 chip is
  Sicos mouse,
  Works ok, needs ClearDTR & Clear RTS in config.
  Index sell a mouse for 10 quid,
  Doesn't work in 3 button mode, but does have nice instructions :-)
  Artec mouse
  Usual dual-protocol mouse, needs `ClearDTR' set in config, NOT
  DynaPoint 3 button serial mouse.
  Usual dual-protocol mouse, needs `ClearDTR' AND `ClearRTS' in Xconfig.
  Genius Easymouse 3 button mouse
  Works fine with Mouseman protocol without the ChordMiddle parameter
  set.  From Roderick Johnstone ([email protected])
  Truemouse, made in Taiwan
  Works OK, needs `ClearDTR' in config. (From Tim MacEachern)
  Champ brand mouse
  Needs to have switch in PC mode, which enables MouseSystems protocol
  also. (From [email protected])
  MicroSpeed mouse
  Usual dual-protocol mouse.
  Venus brand ($7)
  Has a jumper inside to switch between 2 and 3 button mode.  (From
  [email protected] )
  Switched mouse, works OK as MouseSystems in 3-button position.  (From
  [email protected] .)
  Manhattan mouse.
  Switch for `MS AM' / `PC AT' modes, MS mode works fine with the gpm -R
  method. (From [email protected]).
  Inland mouse.
  Switch for `PC/MS' modes, works fine. (From
  qMouse (3-button), FCC ID E6qmouse X31.
  Sells in the USA for about $10. Works with `gpm -t msc -r 20'.  No
  jumpers or switches for MouseSystems 3-button mode. Unreliable in X.
  Does not respond to echo "*n" > /dev/mouse.
  Mitsumi Mouse (2-button), FCC ID EW4ECM-S3101.
  Sells in the USA for about $12. Reliable in X and under gpm, smooth
  double-button. (These two from [email protected])
  PC Accessories mouse that i got from CompUSA for under $10.
  Has PC/MS switch on bottom.  Works OK. (From [email protected])
  First Mouse - seriously cheap at 7.79 pounds at Tempo.
  Dual Microsoft/MouseSystems, mode set by button depress at power-up.
  No switches, no links.  Four wire connection, echo '*n' doesn't work.
  `gpm -R' works a treat. (From [email protected])
  Trust 3-button mouse.
  Dual-mode with switch, works OK as MouseSystems in `PC' mode.  gpm
  doesn't like the Microsoft mode.
  Chic 410
  Works perfectly when kept in ms mode and used with the gpm -R command.
  From Stephen M. Weiss ([email protected])
  KeyMouse 3-button mouse.
  Works OK with ClearDTR and ClearRTS in Xconfig; `-o dtr' needed with
  gpm. (From [email protected])
  Qtronix keyboard `Scorpio 60'
  All three buttons work in MouseSystems protocol.  (From
  [email protected])
  Tecra 720 laptop
  The glidepoint is on /dev/cua0; the stick is on /dev/psaux.  (From
  [email protected])
  Anubis mouse
  Works fine, need to hold down left button whenever switching to the X
  virtual console.  (From Joel Crisp)
  Yakumo No.1900 mouse
  Works with gpm -R -t ms exporting to X.  (From Oliver Schwank)
  Genius `Easy Trak' Trackball
  Is not Microsoft compatible, use Mouseman in the Xconfig and it will
  work fine.  (From [email protected])
  Highscreen Mouse Pro
  `Works fine' says [email protected]
  Logitech CA series
  Works in X using MMseries protocol, at 2400 Baud, 150 SampleRate.
  (Should also apply to Logitech CC, CE, C7 & C9 mice).  (From
  [email protected])
  A4-Tech mouse
  Works OK, needs DTR line under both X and gpm.  (From
  [email protected])
  Vertech mouse
  Normal Microsoft/Mousesystems behaviour, can be soldered for a
  permenant fix.  (From [email protected])
  Boeder M-7 ``Bit Star'' (and other M series apart from M13)
  Switches to Mousesystems protocol by holding any button down at power-
  on.  (From mailto:[email protected])
  Mouse Systems ``Scroll'' Mouse (four buttons and a roller/button)
  Has a 2/3 switch - in mode 3 functions as a three button MouseSystems
  mouse, ignoring extra button & wheel.  Doesn't need ClearRTS/DTR.
  (From [email protected])
  Radio Shack 3-button Serial Mouse
  Model 26-8432, available in Tandy for about 20 quid. Works as
  Mousesystems with ClearDTR. (From [email protected])
  Dexxa serial mouse
  Works fine using Microsoft protocol in Xconfig, no ChordMiddle or
  anything needed.  (From mailto:[email protected])
  Belkin 3 button mouse
  As purchased from Sears (\$10), needs -o rts under gpm (and probably
  ClearRTS under X) when in PC mode.  (From mailto:[email protected])

  14.  Further Information

  ·  Mouse Systems has a web site at  They
     have a Windows driver if you need one.

  ·  The Linux Serial HOWTO is available from mirrors of sunsite around
     the world.  If you don't know where your nearest mirror is, start

  ·  There is a very good explanation of how mice work at

  ·  Fuller details of the Xconfig and XF86Config files are found on the
     relevant man pages, and in the documentation about installing X
     windows such as the Xfree86 HOWTO. Also, see the XFree86 FAQ at a
     mirror of

  ·  Information about gpm can be found on the man page, also try the
     web page of Darin Ernst at

  ·  Lots of information on mice hardware and software can be found at

  15.  Mouse Tail

  Much of the information for this document has been trawled from the
  various linux newsgroups. I am sorry I did not keep a record of
  everyone who has indirectly contributed by this route, thank you all
  very much.

  So, to sum up:

  ·  Even cheap 3 button Microsoft mice can be made to work.

  ·  Configure your copy of X to expect a Mouse Systems mouse.

  ·  Hold down the left button at power-on to switch the mouse to
     MouseSystems mode.

  ·  You might need to hold the left button down when starting X.

  ·  Mice are more intelligent than you think.