First, a NOTE: I am not in any way, shape or form responsible for any
harm that may come to you, your computer, your mouse or other controller
device, or anything whatsoever, through your use of the information
contained in this file. While I believe all of the information to be
accurate, I make no guarantees as to its accuracy and have no guarantee
that you will perform everything in a safe manner or according the
instructions provided. So you're on you're own here; however, it did
work for me.
STUFF YOU MIGHT NEED FOR THIS PROJECT:
--------------------------------------
(items with "+" are for building the box)
( and may not be needed if you plan to )
( modify the bus device directly )
- Bus Mouse/Trakball
+ Electronics Project Box
+ Coffee, tea, soda, milk, water, beer, hard liquor,
Everclear or whatever liquid refreshment/stimulant
you feel necessary to continue
- Atari Mouse Cord (recommended) -OR- joystick cord with all 9
wires -OR- nine-wire conductor and DB-9 connector
- Solder & Soldering Iron + Hot Glue Gun & glue sticks
- Ohmmeter/Multimeter + Drill
- No. 1 Philips and Slot screwdrivers
+ Aspirin or Non-aspirin pain reliever (just in case)
ON WITH THE SHOW
----------------
Here are the pin and signal assignments for the PC Bus mouse and Atari
mouse connectors:
| Bus Mouse | Signal | Atari Mouse | |
| --------------- | ------------------ | ----------- | |
| 1 | Ground | 8 | |
| 2 | Rt Btn | 9 (Right Button) | |
| 3 | -- | - | |
| 4 | -- | - | |
| 5 | LftBtn | 6 (Left Button) | |
| 6 | YA | 3 (Vertical Cursor) | |
| 7 | YB | 4 | |
| 8 | XA | 1 (Horizontal Cursor) | |
| 9 | XB | 2 | |
| 10 | +5v DC |
Note that, as it pertains to this modification, pin 5 is not used on the Atari connector, pin 3 does not exist on the Bus connector, and pin 4 on the Bus connector is not used.
Looking in from the business end of the connectors (i.e., the part
that normally plugs into the computer), the pins are labeled as follows
for the purposes of this mod (this may or may not match any standard
numbering conventions):
Note the blank area at the top of the "Bus Mouse" figure. This is a "key" of sorts to prevent improper insertion of the plug, and is a handy way to differentiate between a Bus plug and a PS/2 plug, both of which are round. Another way to tell the two apart is the Bus configuration has ten places for pins, while the PS/2 configuration has only 6 pins. YOU MUST USE A BUS MOUSE/TRAKBALL FOR THIS PROJECT TO WORK. Serial, PS/2 and MousePort mice do not have the proper signals to work with the Atari mouse port.
Bus Mouse Atari Mouse--------- -----------
/-----\
--------- ------------- / 4 2 1 \ \ 5 4 3 2 1 / | 8 7 6 5 | \ 9 8 7 6 / \ 10 9 / --------- ---------
BEFORE GETTING STARTED:
-----------------------
There's several ways this mod can be done, and you'll want to prepare
for each a little differently. The first step, of course, to read over
all the instructions carefully and make sure you understand them before
proceeding.
Obviously, the mouse/trakball has to plug into the Atari. The best way
to do this is to use the cord from an unused Atari mouse. The second
best way is to use a DB-9 connector, which can be attached directly to
the cord of the bus mouse, or to an un-used Atari mouse cord which can
then be patched to the bus mouse. Note that the mouse cord MUST HAVE
ALL CONDUCTORS AVAILABLE with the exception of pin 5. Not all mice use
the same number of conductors, and many have simply left the unused
conductors out of the cord. You must use a cord which has the required
conductors (1-4, 6-9) available for use. Joystick cables with the
required conductors will also work, but are not as flexible as mouse
cords; the same is true of most other cables you might make up yourself.
To simplify things later on, you might go ahead and determine which wire in the cable(s) are connected to which pins. Each wire should be a different color, which makes it easy to create a table listing each wire color and the pin it goes to. If the wires are all the same color, simply label each wire with a piece of tape and the number of the pin it connects with. You can get this information either by opening up the body of the PC Bus mouse and using an ohmmeter to trace continuity; checking things out visually, or by using a very small divining rod and immense faith in your ability to use it.
TO MODIFY THE BUS MOUSE/TRAKBALL DIRECTLY:
------------------------------------------
Using whatever 9-pin connector/cable combination you have chosen to use, simply connect the pins/wires from the Bus mouse connector to the Atari mouwe connector as described in the chart at the beginning of this text.
If you will be cutting the connector off of the Bus mouse cord and
replacing it with an Atari/DB-9 connector, make sure you have already
generated a listing of what color wires go to what pins! Otherwise
you'll be hard pressed to tell which wires go where and may never get it
working right.
Once the connections have been made, check all of them and if all looks well, plug it in and give it a go. Make sure to check out all functions of the mouse (cursor up/down/left/right, left/right buttons). If it doesn't work properly, refer to TROUBLESHOOTING below for some tips. If it does work, congratualtions!
TO BUILD A BUS MOUSE/TRAKBALL INTERFACE
---------------------------------------
If you have an un-used IBM bus card handy, it can be used to construct a plug-in box which will allow the use of any other bus controller (i.e., mice, trakballs or pen mice) without having to perform further modifications to equipment. The Microsoft Bus mouse comes with an 8-bit ISA Bus card; if the PC Bus mouse you obtained did not come with a card and you do not have another, you might try obtaining just the 10-pin Bus jack from an electronics supply store or via mail order.
My box uses the card that came with the Microsoft Bus mouse. If one bends the metal bracket on the card parallel to each side of the circuit card and cuts the circuit card at the bracket ends, the resulting card will fit into most small electronics project boxes of about 2" x 2" x 3". I took the resulting card to a local Radio Shack and found a box that would fit for under $3.00.
Place the card into the box and determine where to drill two holes: A
big one for the PC Bus mouse to plug into the card, and a smaller one
for the mouse cord which will plug into the Atari.
Once the holes are drilled, use an ohmmeter to determine where, on the "chopped" circuit board, the pins of the jack can be accessed. This allows for easier connecting of the Atari mouse cable to the circuit card. Ideally there should be a row of un-used solder pads on the top of the circuit board, near the jack, which can be used for this purpose. Keep good notes and/or label the solder pads so you know which ones lead to which pins on the bus jack. Also keep in mind that the pin numbers on the jack are mirrored left-to-right, as compared to looking at the bus connector on the mouse itself.
Thread the end of the cable which will be leading to the Atari
connector through the small hole in the project box so that the plug is
outside the box and the leads are accessable within the box. Tie a knot
in the cable about three inches from the ends of the leads to prevent
the cord from being pulled out from the plug end.
Solder the appropriate wires of the Atari cord to the solder pads on the circuit card which match the proper pins on the Bus connector. Before connecting the box to the Atari for testing, double check all connections my using an ohmmeter, making sure the PC Bus pin-to-Atari pin assignments are correct.
Test the box by plugging the Atari connector into the computer and the
Bus mouse into the jack of the circuit card, making sure to test all
functions (left/right/up/down cursor; left/right click). If there's a
God in Heaven and all is right with the world, everything will function
properly. If it doesn't, take a look at TROUBLESHOOTING below.
Once you've verified that all works well, place the ciruit board in the project box so the mouse connector lines up with the hole drilled for it and hot-glue the circuit board in place using plenty of glue along the edges of the metal bracket. Pull the mouse cord to the Atari connector so the knot in the cable is placed against the inside of the project box, making sure the leads to the ciruit board aren't being stressed, and hot glue that in place as well. Before securing the lid to the box, make sure that the PC Bus mouse easily plugs into the connector in the box. Then secure the lid to the box, and you're good to go!
You now have an interface that should let you plug any standard PC Bus
mouse, trakball or cheese grater directly to the Atari without any
further modification. In other words, you won't have to do this again
and won't have the excuse again later, so you might as well sit back and
have that beer now.
TROUBLESHOOTING
---------------
Those making an interface box will likely experience the most
difficulty, as it is easy to lose track of where on the circuit board
one can make a good connection with a particular pin on the connector.
Being careful and meticulous and using a "paper brain" will help avoid
problems later on.
The first thing to do, of course, is to check all connections to make
sure the correct pins are connected to each other, and check each
connection to make sure it is electrically secure and complete. If this
fails, try using some of the tips below, which is basically the same
advice in table form: ;)
| Symptom | Probable Cause | Solution |
| ======================= | ======================= | ===================== |
| Mouse cursor movement | XA/XB or YA/YB signals | Reverse XA/XB signals |
| reversed (left moves | reversed | or horizontal, YA/YB |
| to right, up moves to | signals for vertical | |
| down, etc.) | problems. | |
| Mouse cursor movement | XA/XB and YA/YB | Ensure XA/XB and YA/YB |
| really hosed up (left | signals connected to | signals connected to |
| moves up, up moves | wrong pins | proper pins as per |
| right, etc.) | PC Bus/Signal/Atari | |
| Mouse table | ||
| Right or Left mouse | Signals not connected | Check pin-to-pin |
| button does not work. | _or_ are reversed. | connections for mouse |
| This can be checked | button signals; Check | |
| by trying each button | to ensure Lft Btn and | |
| as if it were the | Rt Btn signals are | |
| other button. | not reversed. | |
| Any given function | Signal not properly | Electrically check |
| does not work. | connected. | the connection for |
| that signal; Check | ||
| pin-to-pin con- | ||
| nections. | ||
| All else fails. | Did not try, or did | Try; Try again. |
| did not try again. |
Michael Parrott
mparrott@hebron.connected.com
Many thanks to everyone who's ever written anything whatsoever about
modifying a bus mouse to work on an Atari computer, whether in textual
or graphic format. I've tried not to draw directly from any other source
for this file, but have surely been influenced by other information I've
found on the subject, so thanks to those folk, whomever they may be,
are defini