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:

1. Remove trackball by inverting unit
2. Locate and remove 2-8 screws (varies by version)
3. Note: Version 3.0-4.0 have screws hidden under label
4. Separate top and bottom case halves
5. Disconnect ribbon cable if present
6. 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:

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

Roller Maintenance (Mechanical Models)

Cleaning rollers:

1. Remove accumulated debris with tweezers
2. Clean with isopropyl alcohol
3. Check for flat spots or grooves
4. 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:

1. Test on known-good ADB port
2. Try different ADB chain position
3. Check for bent pins in connector
4. Verify cable continuity with multimeter
5. 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:

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

Repair method:

1. Disassemble trackball completely
2. Cut cable past break point
3. Strip and tin wire ends
4. Solder to PCB maintaining color code:

 * Red: +5V
 * Black: Ground
 * Green: Data
 * Yellow: Power switch (if present)

1. Add heat shrink for strain relief
2. 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:

1. Desolder defective switch with desoldering braid
2. Note orientation of switch terminals
3. Install new switch ensuring flat mounting
4. Test actuation before reassembly
5. 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:

1. Locate sensor windows (usually 2-4)
2. Clean with cotton swab and isopropyl alcohol
3. Check for scratches on windows
4. Verify LED illumination with digital camera
5. 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:

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

Power Supply Problems

ADB power specifications:

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

Diagnostics:

1. Measure voltage at device
2. Check current draw with ammeter
3. Test with external powered ADB hub
4. 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.

See Also

• Apple Desktop Bus
• Macintosh Portable (integrated trackball)
• PowerBook 100 Series (integrated trackball)
• Trackball Maintenance