Apple Trackball

ADB Trackballs
	Kensington Turbo Mouse Version 4.0 ADB trackball
Manufacturer	Kensington, Logitech, CH Products, others
Type	Pointing device / Trackball
Discontinued	2000 (transition to USB)
Price	US$169-199 (typical retail)
Interface	Apple Desktop Bus
Compatible	All ADB-equipped Macs (System 6.0.7 or later)
Dimensions	Varies by model
Weight	400-600g typical
Predecessor	Serial/quadrature trackballs
Successor	USB trackballs

ADB trackballs were pointing devices designed for use with Apple Desktop Bus-equipped Macintosh computers from the late 1980s through the late 1990s. While Apple never produced a standalone ADB trackball (only integrating them into portable computers), third-party manufacturers filled this market niche with numerous models that became essential tools for desktop publishing, CAD work, and accessibility applications. The most successful was the Kensington Turbo Mouse series, which dominated the Mac trackball market throughout the ADB era.

Historical Context

The introduction of Apple Desktop Bus in 1986 with the Apple IIGS and Macintosh SE created a standardized interface for input devices. This prompted peripheral manufacturers to develop alternatives to the traditional mouse, particularly for users requiring greater precision or those with repetitive strain injuries. Trackballs offered stationary operation ideal for cramped workspaces and reduced arm movement for users with mobility limitations.

The first ADB trackballs appeared in 1987, initially as rebranded or modified versions of existing serial devices. By 1988, purpose-built ADB trackballs emerged with features specifically targeting Macintosh users, including multiple buttons programmable through software and high-resolution tracking mechanisms. The market peaked in the mid-1990s before declining with the transition to USB in 1998-1999.

Major Manufacturers and Models

Kensington Turbo Mouse Series

The Kensington Turbo Mouse, later renamed Expert Mouse for trademark reasons, was the most popular ADB trackball series for Macintosh computers.

Version History:

Version 1.0 (1987): Model #62350 - Quadrature output, rebranded Assimilation Process AP07045
Version 2.0 (1988): Model #62352 - First native ADB interface
Version 3.0 (1989): Model #62360 - Two buttons, ADB passthrough ports, DIP switches
Version 4.0 (1991): Model #64100 - Improved mechanism, side-by-side ADB ports
Version 5.0 (1994): Model #64210 - Four-button configuration, enhanced software support
USB/ADB hybrid (2000): Model #64215 - Final ADB-compatible model with USB primary interface

Technical Specifications (Version 4.0):

Ball diameter: 57mm (2.25 inches) - regulation pool ball size
Resolution: 200 CPI (counts per inch)
Buttons: 2 or 4 depending on version
Tracking: Optical levering technology
ADB ports: 2 passthrough connectors
Compatibility: System 6.0.7 through Mac OS 9.2.2

Logitech TrackMan Series

Logitech entered the Mac trackball market in 1989 with ADB versions of their PC trackballs.

ADB Models:

TrackMan: Original thumb-operated design
TrackMan Stationary: Large ball centered design
MouseMan/TrackMan combo: Convertible mouse/trackball hybrid

Technical Specifications:

Ball diameter: 32mm (thumb models) or 40mm (finger models)
Resolution: 200-300 CPI depending on model
Tracking: Opto-mechanical with slotted wheel encoders
Buttons: 2-3 standard
Software: MouseWare for programmable functions

CH Products RollerMouse

CH Products produced several ADB trackballs targeting both Mac and Apple IIGS users.

Features:

Buttons: 4 total (2 programmable)
ADB passthrough: Single port
Ball diameter: 50mm
Unique feature: Hardware-switchable button mapping

Other Manufacturers

CoStar Stingray: Budget model with 2 buttons
Mouse Systems A3 Trackball: High-end CAD-focused device
Microspeed MacTrac: Included proprietary acceleration software
Curtis MVP Mouse: Combination trackball/touchpad device

Technical Architecture

ADB Protocol Implementation

ADB trackballs communicated using the standard Apple Desktop Bus protocol:

Device addressing:

Default address: $3 (relative positioning device)
Handler ID: $01 for standard mouse, $02 for extended mouse
Polling rate: 100 Hz maximum
Data format: 2-byte packets for X/Y deltas

Register structure:

Register 0: Device data (movement and button state)
Register 1: Reserved
Register 2: Status flags and LED state
Register 3: Device handler ID and address

Tracking Technologies

Opto-Mechanical

Most ADB trackballs used opto-mechanical tracking:

Components:

Encoders: Slotted wheels interrupting infrared beam
Rollers: X and Y axis contact with ball
Resolution: 100-400 CPI typical
Maintenance: Regular cleaning required

Common issues:

Roller contamination from skin oils and debris
Encoder wheel damage from forced movement
Infrared emitter/detector degradation

Optical Levering

Kensington's proprietary technology used optical sensors to detect ball rotation:

Mechanism:

Sensors: Four-cell linear optical arrays
Pattern detection: Contrast stripes on ball surface
Processing: Hardware quadrature generation
Advantage: More consistent tracking than mechanical

Button Implementation

Mechanical switches:

Type: Typically Omron D2F series microswitches
Lifespan: 1-5 million clicks rated
Actuation force: 75-150 grams
Modification: Some users replaced with lighter switches

Software programmability:

System 7 and later: Third-party control panels
Functions: Click, double-click, drag lock, modifier keys
Acceleration curves: Customizable through software

Internal Construction

Kensington Turbo Mouse Disassembly

Tools required:

Phillips screwdriver #1
Plastic spudgers
Isopropyl alcohol for cleaning

Disassembly procedure:

Remove trackball by inverting unit
Locate and remove 2-8 screws (varies by version)
Note: Version 3.0-4.0 have screws hidden under label
Separate top and bottom case halves
Disconnect ribbon cable if present
Remove PCB mounting screws

Internal components:

Main PCB: Contains ADB controller and button switches
Sensor board: Optical or mechanical encoders
Cable: Usually non-removable, strain relief critical
Bearings: Ruby or ceramic ball supports

Common Maintenance Procedures

Ball and Bearing Cleaning

Cleaning schedule:

Light use: Every 3 months
Heavy use: Monthly
Signs needed: Erratic cursor, increased resistance

Procedure:

Remove ball and inspect for damage
Clean ball with mild soap and water
Clean bearings with isopropyl alcohol on cotton swab
For optical models, clean sensor windows
Lubrication generally not recommended

Roller Maintenance (Mechanical Models)

Cleaning rollers:

Remove accumulated debris with tweezers
Clean with isopropyl alcohol
Check for flat spots or grooves
Replace foam cleaning pads if degraded

Roller replacement:

Source from donor units
Some compatible with mouse rollers
Ensure proper spring tension

Common Issues and Diagnostics

Tracking Problems

**Tracking Issue Diagnostics**
Symptom	Likely Cause	Test Method	Solution
Cursor jumps erratically	Dirty sensors/rollers	Visual inspection	Clean thoroughly with alcohol
Cursor won't move one axis	Failed encoder or roller	Swap X/Y mechanically	Replace encoder assembly
Intermittent movement	Loose cable or connector	Wiggle test at strain relief	Resolder connections
Cursor drift	Contaminated ball surface	Clean ball, check for damage	Replace ball if worn
Sluggish response	Software acceleration disabled	Check control panel settings	Reinstall driver software

Button Failures

**Button Problem Diagnostics**
Problem	Symptoms	Cause	Repair Method
Click not registering	Intermittent or no response	Worn microswitch	Replace switch (Omron D2F)
Double-clicking	Single click registers twice	Dirty contacts	Clean or replace switch
Stuck button	Button remains depressed	Mechanical binding	Disassemble and realign
Mushy feel	No tactile feedback	Spring fatigue	Replace entire switch

ADB Communication Issues

Diagnostic steps:

Test on known-good ADB port
Try different ADB chain position
Check for bent pins in connector
Verify cable continuity with multimeter
Test with minimal ADB chain

Common causes:

Excessive bus current draw (>500mA total)
Cable damage at strain relief
Corroded connector pins
Failed ADB transceiver chip

Repair Procedures

Cable Repair

ADB trackballs typically had permanently attached cables prone to failure at the strain relief.

Testing cable integrity:

Use multimeter in continuity mode
Check each conductor (4 wires: +5V, Ground, Data, PSW)
Flex cable while testing to find intermittent breaks
Common failure point: 2-3 inches from device

Repair method:

Disassemble trackball completely
Cut cable past break point
Strip and tin wire ends
Solder to PCB maintaining color code:
1. Red: +5V
2. Black: Ground
3. Green: Data
4. Yellow: Power switch (if present)

Add heat shrink for strain relief
Consider adding flexible silicone at exit point

Switch Replacement

Identifying switch type:

Most use Omron D2F series microswitches
Some use Alps SKHHAJ series
Measure physical dimensions before ordering

Replacement procedure:

Desolder defective switch with desoldering braid
Note orientation of switch terminals
Install new switch ensuring flat mounting
Test actuation before reassembly
Adjust actuator arm if necessary

Bearing Replacement

Ruby/Ceramic bearings (Kensington):

Part identification: Usually 3mm ceramic balls
Source: Industrial bearing suppliers (Si3N4 ceramic)
Installation: Glue with cyanoacrylate adhesive
Alignment: Critical for smooth operation

Roller replacement (Mechanical):

Clean shaft thoroughly
Check spring tension
Ensure perpendicular alignment
Test free rotation before assembly

Optical Sensor Cleaning

For optical trackballs:

Locate sensor windows (usually 2-4)
Clean with cotton swab and isopropyl alcohol
Check for scratches on windows
Verify LED illumination with digital camera
Clean ball pattern if applicable

Electronic Troubleshooting

ADB Controller Issues

Common controller chips:

Kensington: Custom ASIC or licensed Apple chip
Logitech: Proprietary controller
Generic: Often 8051-based microcontroller

Testing controller:

Check for +5V at chip power pins
Verify clock signal (usually 1-4 MHz)
Monitor data line for activity
Controller replacement usually not feasible

Power Supply Problems

ADB power specifications:

Voltage: +5V ±5%
Current: 100mA maximum per device
Total bus: 500mA maximum

Diagnostics:

Measure voltage at device
Check current draw with ammeter
Test with external powered ADB hub
Verify host computer PSU stability

Software and Drivers

System Software Requirements

Minimum requirements:

System 6.0.7: Basic ADB support
System 7.0: Enhanced button programmability
System 7.5: Native acceleration control
Mac OS 8-9: Full USB/ADB compatibility

Third-Party Software

Kensington MouseWorks:

Versions: 1.0 (System 6) through 5.0.2 (Mac OS 9)
Features: Button programming, acceleration curves, chord clicks
Installation: Control panel and extension

Logitech MouseWare:

Compatibility: System 6.0.8 through Mac OS 9.2.2
Features: Similar to MouseWorks plus game profiles
Known issues: Conflicts with some USB drivers

Generic drivers:

USB Overdrive: Supported some ADB devices
SteerMouse: Limited ADB compatibility
System native: Basic 1-button operation always available

Modifications and Enhancements

Ball Replacements

Alternative balls:

Pool balls: Regulation 2.25" for Kensington
Phenolic resin: Better than standard plastic
Custom colors: Popular modification for personalization
Weight considerations: Heavier balls increase momentum

Switch Modifications

Lighter actuation:

Replace Omron D2F-01 (150g) with D2F-L (75g)
Add lever arm extension for mechanical advantage
Some users removed springs entirely

Cleaning Mechanism Improvements

Foam pad replacement:

Material: Low-density polyurethane foam
Thickness: 2-3mm typical
Attachment: Double-sided tape or adhesive
Function: Continuous roller cleaning

Preventive Maintenance

Regular Maintenance Schedule

Weekly (heavy use):

Wipe ball with microfiber cloth
Check for debris around bearings

Monthly:

Remove ball and clean bearings
Inspect cable for damage
Test all buttons

Quarterly:

Full disassembly and cleaning
Check internal connections
Update driver software if available

Annually:

Consider preventive switch replacement
Inspect PCB for capacitor issues
Document any degradation

Storage Recommendations

Long-term storage:

Clean thoroughly before storage
Store with ball removed
Protect from dust with cover
Avoid extreme temperatures
Coil cable loosely to prevent damage

Modern Usage

ADB to USB Conversion

Hardware adapters:

Griffin iMate: Discontinued but highly regarded
Wombat: Current production, programmable
DIY solutions: Teensy-based converters

Compatibility issues:

Power requirements may exceed USB limits
Button mapping requires configuration
Some acceleration features lost
Latency typically 1-3ms added

Replacement Parts Sources

Components still available:

Microswitches: Electronics suppliers
Bearings: Industrial suppliers
Cables: Generic 4-conductor
Cleaning supplies: Standard computer maintenance

Discontinued parts:

Original balls: Check vintage computer forums
Optical sensors: Salvage from donor units
Custom ASICs: No replacement available
Specific plastic parts: 3D printing possible

Collector Information

Desirable Models

High value:

Kensington Turbo Mouse 5.0 (4-button)
Mouse Systems A3 Trackball
Rare color variants (white, black)
New-in-box examples

Common models:

Kensington Turbo Mouse 3.0/4.0
Logitech TrackMan
CH Products RollerMouse

Preservation Guidelines

Prevent UV exposure to reduce yellowing
Maintain 40-60% humidity
Regular exercise prevents mechanism seizure
Document serial numbers and versions
Preserve original software and documentation

Legacy and Impact

ADB trackballs represented a significant ergonomic alternative during the desktop publishing revolution of the late 1980s and 1990s. They were particularly popular among:

Graphic designers: Precision for detailed work
CAD operators: Reduced arm movement for long sessions
Users with disabilities: Accessibility advantages
Musicians: Used for MIDI sequencing (notably Prince used Kensington Turbo Mouse)

The technology and design principles developed for ADB trackballs directly influenced modern USB and wireless trackballs, with many current models maintaining similar ball sizes, button layouts, and tracking mechanisms established during the ADB era.