Trackballs

This page should contain brief descriptions of various trackballs available, and details of their setup. If any one portion of the page starts getting a little too long, a seperate page may be started for that topic.

2.25" Trackballs

Available from Happ, Suzo, Ultimarc and others.

Two and a quarter inches is the same size as a (U.S.) regulation billiard ball.

3" Trackballs

Available from Happ, Suzo, Ultimarc and others.

4.5" Atari Trackballs (Missile Command, Atari Football)

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4.5" trackballs (w/o optical boards)

These giant trackballs are sometimes known as 4-inch, but are actually four and a half inches in diameter. They were some of the first trackballs put into use, and are made of machined aluminum; clearly designed to survive intense abuse.

Putting one of these in your control panel is quite a commitment in terms of real estate. The metal frame is 6" square, 3.5" tall, and the optical boards stick an aditional 2 inches beyond two of the corners, an effective 64 square inch footprint.

Happ sells a 4.5" trackball. The ball itself is usable in an Atari 4.5" (a 4.5" diameter sphere is a 4.5" diameter sphere), but the mechanism itself is a different, less industrial design.

Any 4.5" diameter ball, particularly a candle-pin and/or duck-pin bowling ball, is a swap-out replacement for the 25+ year old originals.

The original optical boards on these are fairly easy to interface with an Opti-PAC (and therefore most other optical control interfaces). This is the pin-out for the 10-pin molex plug found on the optical boards:

1	no signal
2	no signal
3	no signal
4	Axis 1
5	no signal
6	no signal
7	no signal
8	Axis 2
9	+5v
10	ground

There were a number of slightly different boards with this same pin-out.

On an Opti-PAC, the "A/HI" jumper should be set.

There are a few vendors, particularly The Real Bob Roberts, that sell replacement bearings and steel roller-shafts for these (they are often referred to as 4" trackball rollers).