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.

4.5" Atari Trackballs (Missile Command, Atari Football)

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

Happs 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

On an optipac the "A/HI" jumper should be set.

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

There are a few places that sell replacement bearings and roller-shafts for these, they are often referred to as 4" trackball rollers.