Editing Apple Desktop Bus Mouse

{{Infobox computer peripheral
| name         = Apple Desktop Bus Mouse
| image        = [[File:Apple_Desktop_Bus_Mouse.jpg|250px]]
| caption      = Apple Desktop Bus Mouse (Model M0142)
| manufacturer = Apple Computer, Inc.
| type         = Pointing device
| release date = September 1986
| discontinued = January 1993
| price        = US$119 (retail)
| interface    = [[Apple Desktop Bus]]
| compatible   = Apple IIGS, Macintosh SE, Macintosh II, all ADB-equipped Macs
| dimensions   = 93 mm L × 61 mm W × 36 mm H
| weight       = 175 g (6.2 oz)
| predecessor  = [[Apple Mouse]] (DE-9)
| successor    = [[Apple Desktop Bus Mouse II]]
| model        = M0142, G5431, A9M0331
}}

The '''Apple Desktop Bus Mouse''' was the first mouse designed for the [[Apple Desktop Bus]] (ADB) interface, introduced in September 1986 with the [[Apple IIGS]]. Released alongside Apple's transition from proprietary connectors to the standardized ADB system, it became the standard mouse for Macintosh computers from the [[Macintosh SE]] and [[Macintosh II]] through early 1993. The mouse retained the angular, blocky design of its DE-9 predecessor but adopted the Snow White design language with uniform Platinum gray coloring.

== Model Variants ==

Three model numbers were assigned to the Apple Desktop Bus Mouse during its production run:

* '''A9M0331''' – Original model introduced with the Apple IIGS (September 1986)
* '''G5431''' – Version bundled with Macintosh II and SE (March 1987)
* '''M0142''' – Consolidated model number used from 1988-1993

Despite different model numbers, all variants were functionally identical. Manufacturing occurred in Taiwan (early models), Ireland, and later Singapore facilities.

== Design & Construction ==

=== Physical Characteristics ===
The ADB Mouse maintained the rectangular footprint of earlier Apple mice but featured a lower, triangular profile measuring 93mm × 61mm × 36mm. The single button spanned the entire front section of the mouse, providing a large clicking surface. The case was injection-molded ABS plastic in Apple's standard Platinum gray (Pantone 423C), with only the cable and connector retaining the darker "Smoke" gray color.

=== Internal Components ===
The mouse utilized mechanical ball tracking with the following key components:

* '''Tracking mechanism:''' 19mm rubber-coated steel ball
* '''Optical encoders:''' Two perpendicular slotted wheels with infrared LED/phototransistor pairs
* '''Controller chip:''' Various manufacturers including:
  * Mitsumi custom ADB controller
  * Logitech 42c60p5625
  * IC Designs custom ASIC
* '''Microswitch:''' Omron D2F series rated for 1 million clicks
* '''Circuit board:''' Single-sided PCB with through-hole components

=== Manufacturing Variations ===
Two primary internal designs existed:

'''Taiwan/Singapore manufacture:'''
* Single consolidated PCB
* Integrated controller chip
* Cost-reduced component count

'''Ireland manufacture:'''
* Dual PCB design (main board + switch board)
* Discrete logic implementation
* Higher component quality

== Technical Specifications ==

=== ADB Interface ===
The Apple Desktop Bus Mouse communicated using the ADB protocol over a 4-pin mini-DIN connector:

{| class="wikitable" style="width:50%; text-align:center;"
|+'''ADB Connector Pinout'''
! Pin !! Signal !! Description
|-
| 1 || ADB Data || Bidirectional serial data line
|-
| 2 || PSW || Power switch signal (unused on mouse)
|-
| 3 || +5V || Power supply (100mA max draw)
|-
| 4 || GND || Ground reference
|}

=== Communication Protocol ===
* '''Data rate:''' Up to 125 kbit/s theoretical (typically 10-50 kbit/s)
* '''Bit encoding:''' Self-clocking duty cycle modulation
  * Logic 0: Low 65μs, High 35μs
  * Logic 1: Low 35μs, High 65μs
* '''Default address:''' $3 (reassignable via bus enumeration)
* '''Polling rate:''' ~100 Hz typical

=== Device Registers ===
The ADB Mouse implemented standard ADB register functionality:

* '''Register 0:''' Mouse movement data (2 bytes)
  * Byte 0: Button state (bit 7) + X movement delta
  * Byte 1: Button state (bit 7) + Y movement delta
* '''Register 1:''' Reserved (unused)
* '''Register 2:''' Reserved (unused)
* '''Register 3:''' Device identification and address
  * Default handler ID: $01 (standard mouse)

=== Tracking Performance ===
* '''Resolution:''' 100 counts per inch (CPI)
* '''Maximum tracking speed:''' 10 inches/second
* '''Sampling rate:''' Mechanical encoder dependent (~200 Hz)

== ADB System Architecture ==

The Apple Desktop Bus represented a major shift in Apple's peripheral connectivity strategy. Key features included:

* '''Multi-device support:''' Up to 16 devices on a single bus
* '''Daisy-chaining:''' Devices could be connected in series
* '''Hot-swapping:''' Theoretical support (not recommended on most systems)
* '''Power distribution:''' Bus supplied up to 500mA at 5V total
* '''Collision detection:''' Automatic address conflict resolution

The mouse typically operated at address $3, with the keyboard at address $2. During system initialization, the ADB Manager would enumerate devices and resolve any address conflicts through a sophisticated random address generation scheme.

== Common Modifications ==

=== Two-Button Conversion ===
Enthusiasts discovered that most ADB controller chips included support for a second button, though Apple never implemented it. Common modifications included:

* Identifying the unused second button pin on the controller chip
* Adding a tactile switch connected to this pin and ground
* Modifying the case to accommodate the additional button
* Software support via third-party control panels

=== Optical Sensor Upgrade ===
Modern retrofit kits allow replacement of the mechanical ball system with optical tracking:

* TT Design's ADB Optical Mouse Retro Board
* Uses RP2040 microcontroller with modern optical sensor
* Maintains original 100 CPI default with adjustable settings
* Compatible with original ADB protocol and timing

== Maintenance & Repair ==

=== Cleaning Procedure ===
Regular maintenance was essential for reliable operation:

# Remove the retaining ring on the bottom of the mouse
# Extract the tracking ball
# Clean ball with isopropyl alcohol
# Remove lint and debris from encoder wheels using compressed air
# Clean encoder wheel surfaces with cotton swab and IPA
# Reassemble in reverse order

=== Common Failures ===
* '''Erratic cursor movement:''' Dirty encoder wheels or worn ball
* '''Button failure:''' Worn microswitch (replaceable with D2F series)
* '''Intermittent connection:''' Broken wires at cable strain relief
* '''Complete failure:''' ADB controller chip damage (often from hot-swapping)

=== ADB Port Safety ===
The ADB port lacked proper protection against hot-swapping on most systems. Connecting or disconnecting devices while powered could blow the ADB fuse on the motherboard, requiring professional repair or fuse replacement.

== Historical Context ==

The Apple Desktop Bus Mouse marked several important transitions:

* '''First ADB peripheral:''' Introduced the new connection standard alongside the Apple IIGS
* '''Design language shift:''' Fully embraced Snow White industrial design
* '''Manufacturing globalization:''' Production spread across multiple facilities worldwide
* '''Extended compatibility:''' Worked with all ADB-equipped systems through 1999

Production estimates suggest over 4 million units manufactured during its 6.5-year production run.

== Software Compatibility ==

=== System Software ===
* '''Apple IIGS:''' GS/OS with built-in mouse driver
* '''Macintosh:''' System 3.2 through Mac OS 9.2.2
* '''Third-party:''' MouseKeys, QuicKeys, and other enhancement utilities

=== Control Panels ===
* '''Mouse control panel:''' Tracking speed adjustment (System 6.0+)
* '''CloseView::''' Cursor size and visibility options
* '''Third-party tools:''' Added acceleration curves and button customization

== Collector Information ==

=== Identification ===
* '''Early models (1986-1988):''' Larger printed label with two screws
* '''Later models (1988-1993):''' Smaller label with single center screw
* '''Serial number format::''' First letter indicates year, second indicates country

=== Condition Assessment ===
* '''Case yellowing:''' Common due to brominated flame retardants or UV light
* '''Cable integrity:''' Check for cracks at strain relief points
* '''Mechanical wear:''' Test ball retention and encoder wheel movement
* '''Button feel:''' Should have distinct tactile feedback

=== Modern Usage ===
* '''ADB-to-USB converters:''' Griffin iMate (discontinued), Wombat adapter
* '''Retrobrighting:''' Possible but risky for painted Platinum plastic
* '''Replacement parts:''' NOS balls and microswitches still available

== Related Accessories ==
* [[Apple Desktop Bus Keyboard]]
* [[Apple Desktop Bus Mouse II]]
* [[Macintosh Mouse Pad]]
* [[ADB Extension Cable]]

[[Category:Apple Vintage Accessories]]
[[Category:Apple Desktop Bus]]