Apple Adjustable Keyboard

Apple Adjustable Keyboard
Apple Adjustable Keyboard M1242 with separate numeric keypad
Manufacturer	Apple Computer, Inc.
Type	Ergonomic split keyboard
Discontinued	1994
Price	US$219 (retail)
Interface	Apple Desktop Bus
Compatible	All ADB-equipped Macs (System 6.0.7 or later)
Dimensions	Main unit: 530 mm W × 250 mm D × 65 mm H (at maximum split)
Weight	2.1 kg (4.6 lbs) with keypad
Predecessor	None (first Apple ergonomic keyboard)
Successor	None (last Apple ergonomic keyboard)
Model	M1242

The Apple Adjustable Keyboard was Apple's sole venture into the ergonomic keyboard market, introduced in March 1993 for the Macintosh family of computers. Model M1242 featured a split alphanumeric section that could pivot up to 30 degrees from center, contoured palm rests, and a separate numeric keypad containing function keys and navigation controls. The keyboard utilized Alps SKFS low-profile mechanical switches for the main keys while implementing recessed microswitch buttons for function and special keys. Production ceased in 1994 after lukewarm market reception and criticism of its construction quality, marking both Apple's first and final attempt at an adjustable ergonomic keyboard design.

Development Context

The Apple Adjustable Keyboard emerged during a period of heightened awareness about repetitive stress injuries (RSI) in the computer industry. By 1992, multiple lawsuits had been filed against computer manufacturers alleging that poor keyboard design contributed to carpal tunnel syndrome and other musculoskeletal disorders. Apple's response was to develop an ergonomic solution that would address these concerns while maintaining compatibility with existing Macintosh systems.

Development began in 1992 with a focus on reducing wrist pronation and ulnar deviation—primary contributors to RSI. The design team studied existing ergonomic keyboards including the Kinesis Advantage and early Microsoft prototypes, ultimately settling on a split design that balanced ergonomic benefits with user familiarity. The keyboard was positioned as a premium accessory for professional users who spent extended periods typing.

Apple's timing coincided with increased corporate interest in workplace ergonomics. The Occupational Safety and Health Administration (OSHA) had begun developing ergonomic standards, and employers sought solutions to reduce worker compensation claims related to RSI. The Adjustable Keyboard targeted this market segment with claims of reducing typing stress through its split design and neutral wrist positioning.

Physical Design

Split Mechanism

The keyboard's defining feature was its hinged center that allowed the alphanumeric section to split into two halves:

• Hinge location: Rear center of keyboard base
• Split points: Between 5/6, T/Y, G/H, and B/N keys
• Maximum angle: 30 degrees total (15 degrees per side)
• Adjustment: Continuous positioning, friction-based retention
• Spacebar: Remained fixed in center, enlarged for accessibility

The hinge mechanism employed a metal base plate that provided structural support while allowing smooth adjustment. Users could position the keyboard from a traditional straight configuration to the maximum split angle without tools or locking mechanisms. The friction-based system maintained position during use but allowed easy readjustment.

Case Construction

The keyboard case utilized a multi-layer design:

• Upper housing: Platinum gray ABS plastic matching Snow White design language
• Base plate: Steel reinforcement for rigidity and hinge support
• Lower housing: Textured bottom with rubber feet
• Thickness: Significantly thicker than contemporary Apple keyboards
• Finish: Matte texture consistent with professional Macintosh systems

Palm Rests

Three contoured palm rests were included:

• Main keyboard rests: Two pieces, one per split section
• Keypad rest: Single piece for numeric keypad
• Material: Hard ABS plastic with textured surface
• Attachment: Friction fit, prone to detachment when lifting keyboard
• Profile: Ergonomically contoured to promote neutral wrist position

Adjustable Feet

Standard flip-down feet provided slope adjustment:

• Positions: Two angles (flat and raised)
• Location: Rear edge of main unit and keypad
• Construction: Integrated plastic tabs
• Criticism: Lacked vertical height adjustment for optimal ergonomics

Numeric Keypad Unit

The separate numeric keypad represented Apple's third and final detached keypad offering:

Layout Configuration

• Left column: F1-F15 function keys (unusual 15-key arrangement)
• Center section: Navigation cluster with inverted-T arrow keys
• Right section: Standard numeric keypad
• Special keys: Home, End, Page Up, Page Down, Help, Forward Delete
• Total keys: 46 keys plus template overlay area

Physical Specifications

• Dimensions: 190mm W × 180mm D × 45mm H
• Weight: 0.6 kg (1.3 lbs)
• Cable: 300mm ADB cable (attached)
• Positioning: Could be placed on either side of main keyboard
• Palm rest: Included matching contoured rest

Template System

A clear plastic overlay covered the function keys:

• Purpose: Allow custom labeling for application-specific functions
• Attachment: Held by pegs similar to Extended Keyboard design
• Compatibility: Accepted standard function key templates
• Material: Thin transparent plastic, removable

Technical Specifications

Electrical Characteristics

• Interface: Apple Desktop Bus (ADB)
• Connectors: Two 4-pin mini-DIN ports per unit (four total)
• Power consumption: 35mA typical (main unit), 15mA (keypad)
• Operating voltage: 4.75V - 5.25V DC
• Data rate: 10 kbit/s maximum
• Device addressing: Separate addresses for keyboard and keypad

ADB Implementation

• Main keyboard address: Default $2
• Keypad address: Default $3
• Handler ID: $02 (standard ADB keyboard)
• Polling: 100 Hz maximum per device
• Daisy chain: Supported through dual ports on each unit

System Requirements

• Minimum OS: System 6.0.7
• Maximum compatibility: Mac OS 9.2.2
• Driver software: Included on 3.5" floppy disk
• Hardware: Any Macintosh with ADB port
• Last compatible system: Power Macintosh G3 (Blue and White)

Switch Technologies

Alps SKFS Series (Main Keys)

Specifications:

• Type: Tactile, low-profile
• Actuation force: 65g ± 10g
• Pre-travel: 1.5mm
• Total travel: 2.5mm
• Tactile characteristic: Sharp feedback without click
• Construction: Simplified mechanism, 6-8 components
• Keycap mount: Alps-compatible but lower profile

The SKFS switches represented Alps Electric's low-profile mechanical solution. The 1994 Alps catalogue described them as having a "sharp 'click' feel with positive feedback," though the switches produced minimal acoustic output. The tactile leaf design positioned a movable center section in front of an open chamber, creating tactility without the click sound associated with traditional mechanical switches.

The switches achieved their low profile through a compact internal design that reduced component count compared to Alps SKCM series. The slider mechanism stood significantly shorter than standard Alps switches, necessitating special low-profile keycaps. This design compromise contributed to the keyboard's overall thickness despite the reduced switch height.

Microswitch Buttons (Function/Special Keys)

Specifications:

• Type: Momentary tactile button
• Actuation force: 100g ± 15g (significantly higher than main keys)
• Travel: 0.5mm
• Feedback: Distinct tactile click
• Mounting: PCB-mounted, recessed housing
• Appearance: Small circular buttons, telephone-style

The function keys, escape key, and special controls used recessed microswitches rather than mechanical key switches. These "chiclet-style" buttons required considerably more force to actuate than the main keyboard keys. Users frequently criticized this design choice, noting that the increased force required for function keys could exacerbate rather than alleviate repetitive stress injuries.

Special Controls

The right side of the main keyboard featured unique audio controls:

• Volume Up/Down: Circular microswitch buttons
• Mute: Circular microswitch button
• Record: Red circular button for audio input activation
• Implementation: Hardware-level control via ADB commands
• Compatibility: Supported in System 7.0 and later

Internal Construction

PCB Design

Main keyboard PCB:

• Layers: Double-sided with through-hole plating
• Controller: Custom Apple ASIC for ADB communication
• Matrix: 8×16 scanning matrix
• Components: Mix of surface-mount and through-hole
• Flexibility: Slight flex required for split operation

Keypad PCB:

• Separate controller ASIC
• Independent ADB addressing
• Simpler matrix design (6×8)
• Integrated cable attachment point

Assembly Architecture

The complex assembly reflected the keyboard's adjustable design:

1. Steel base plate with integrated hinge mechanism
2. Main PCB mounted to base plate with flexibility zones
3. Switch mounting through PCB to base plate
4. Upper case assembly with split accommodation
5. Palm rest attachment points
6. Dual ADB port modules

Cable System

Two cable types were included:

• Short cable: 300mm for close positioning
• Long cable: 1.8m coiled cable for standard placement
• Keypad cable: Fixed 300mm cable
• Construction: 4-conductor shielded cable
• Connectors: Mini-DIN 4-pin male

Manufacturing Information

Production Details

• Manufacturing location: Singapore and Taiwan facilities
• Production period: March 1993 - Late 1994
• Estimated production: 50,000-75,000 units
• OEM partners: Alps Electric (switches), Unknown (assembly)
• Quality control: High rejection rate reported

Model Identification

• Model number: M1242 (keyboard and keypad shared number)
• FCC ID: BCGM1242
• Part number: M1242LL/A (US version)
• Family number: Included in packaging and documentation

Serial Number Format

Format: PPYWWNNNNNN

• PP: Plant code
• Y: Year (3=1993, 4=1994)
• WW: Week number
• NNNNNN: Sequential unit number

Packaging

The distinctive trapezoid-shaped box contained:

• Layer 1: Main keyboard with palm rests
• Layer 2: Numeric keypad with palm rest
• Layer 3: Cables, software disk, documentation
• Design: Three-tier "bento box" arrangement
• Materials: Recycled cardboard with minimal plastics

Software Support

Included Software

The keyboard shipped with a 3.5" floppy disk containing:

• Adjustable Keyboard Driver: Enhanced ADB driver
• Control Panel: Key repeat and delay settings
• Macro Utility: Basic function key programming
• Documentation: Electronic manual in TeachText format

Operating System Integration

• System 6.0.7-7.0: Required driver installation
• System 7.1-7.6: Native support, enhanced features
• Mac OS 8-9: Full compatibility maintained
• Mac OS X: Limited support via Classic environment

Function Key Mapping

The 15 function keys offered unique mapping options:

• F1-F4: Suggested for Undo, Cut, Copy, Paste
• F5-F12: Application-specific functions
• F13-F15: System-wide functions (uncommon)
• Programmability: Limited to macro software

Reception and Criticism

Professional Reviews

The keyboard received mixed professional reviews upon release:

InfoWorld (May 1993): Criticized the keyboard's bulk, high price, and questionable ergonomic benefits. The review noted that the chiclet-style function keys required excessive force and could potentially increase strain rather than reduce it.

PC Magazine (March 1993): Included the keyboard in an ergonomic keyboard roundup, noting its unique split design but questioning the value proposition compared to PC-compatible alternatives that cost significantly less.

MacWorld (June 1993): Praised the concept but criticized execution, particularly the flimsy palm rest attachment and lack of vertical adjustment. The review concluded that dedicated ergonomic keyboard manufacturers offered superior solutions.

User Reception

Common user complaints included:

• Size: Excessive desk space requirements
• Build quality: Perceived as flimsy despite premium price
• Function keys: Difficult to press, poor tactile feedback
• Palm rests: Constantly detaching during use
• Key layout: Escape and function key placement criticized
• Value: High price not justified by features or quality

Positive feedback centered on:

• Split angle: Effective for reducing ulnar deviation
• Switch quality: Alps SKFS switches well-regarded
• Separate keypad: Flexibility in positioning appreciated
• Audio controls: Hardware volume control valued

Market Performance

The keyboard failed to achieve commercial success:

• Sales: Well below Apple's projections
• Market share: Minimal penetration in ergonomic keyboard segment
• Corporate adoption: Limited despite targeting business users
• Discontinuation: Quietly removed from catalog in late 1994
• Inventory: Excess stock sold through 1995

Common Issues and Solutions

Mechanical Problems

Troubleshooting Guide

Problem	Cause	Solution	Difficulty
Palm rests detach	Weak friction fit	Add adhesive strips or modify clips	Easy
Split angle won't hold	Worn hinge friction	Tighten hinge mechanism	Moderate
Function keys stick	Debris in microswitches	Clean with compressed air	Easy
Key chatter	Alps switch contamination	Clean or replace switch	Moderate
ADB not recognized	Cable damage	Test continuity, replace cable	Difficult
Keypad intermittent	Loose cable connection	Reseat or replace cable	Moderate

Maintenance Procedures

Switch cleaning (Alps SKFS):

1. Remove keycap carefully (fragile mounting)
2. Apply 90% isopropyl alcohol sparingly
3. Actuate switch 10-15 times
4. Allow complete evaporation
5. Test switch response

Microswitch restoration:

1. Remove button cap if possible
2. Spray contact cleaner into switch
3. Rapidly actuate 20-30 times
4. Allow to dry completely
5. Consider replacement if unsuccessful

Disassembly Process

Required tools:

• Phillips screwdriver #1 and #2
• Plastic spudgers
• Small flathead screwdriver
• Anti-static mat

Procedure:

1. Document cable routing and connections
2. Remove bottom case screws (note varying lengths)
3. Carefully separate case halves at split point
4. Disconnect internal ribbon cables
5. Remove PCB mounting screws
6. Extract PCB/switch assembly
7. Access hinge mechanism from below

Modern Usage

ADB to USB Conversion

Compatible adapters:

• Griffin iMate: Works but discontinued, limited to Mac OS 10.2
• Wombat: Recommended current solution, bidirectional
• TMK Converter: DIY option, requires programming
• ADB2USB: Commercial solution, limited availability

Challenges:

• Split keyboard and keypad require two adapters
• Function key mapping problematic
• Audio controls non-functional
• High combined adapter cost

Restoration Considerations

Retrobrighting:

• Less effective due to textured surface
• Uneven results common
• Palm rests particularly prone to yellowing
• 6% hydrogen peroxide recommended

Parts availability:

• Alps SKFS switches: Extremely rare
• Microswitches: Generic replacements possible
• Keycaps: No aftermarket options
• Cables: Must fabricate custom replacements

Preservation Guidelines

• Storage: Keep assembled to prevent hinge wear
• Temperature: 15-25°C optimal
• Humidity: 40-60% to prevent corrosion
• Positioning: Store flat, avoid weight on split section
• Cables: Avoid tight coiling, store loosely

Collector Information

Market Value (2024)

Current Market Prices (USD)

Condition	Complete Set	Keyboard Only	Keypad Only
Poor (yellowed, worn)	$50-100	$30-60	$20-40
Good (functional, yellowed)	$100-180	$60-100	$40-60
Excellent (minimal yellowing)	$180-280	$100-160	$60-80
Mint (boxed, complete)	$280-400	N/A	N/A

Rarity Factors

• Complete sets: Increasingly rare due to separation
• Box and documentation: Very rare, adds significant value
• Working condition: Many have failed microswitches
• Cables: Often missing or damaged
• Software disk: Frequently absent

Authentication Points

• Verify M1242 model number on both units
• Check for matching serial number prefixes
• Confirm Alps SKFS switches (remove keycap)
• Inspect hinge mechanism for damage
• Verify all three palm rests present
• Check for period-appropriate ADB cables

Legacy and Impact

The Apple Adjustable Keyboard represented both a bold experiment and a cautionary tale in Apple's peripheral history. Its commercial failure effectively ended Apple's involvement in the ergonomic keyboard market, with the company never again attempting a split or adjustable design. The keyboard's poor reception contributed to Apple's subsequent focus on thin, minimalist keyboard designs that prioritized aesthetics over ergonomic considerations.

Despite its failures, the keyboard introduced several noteworthy innovations. The hardware audio controls predated similar features on later Apple keyboards by several years. The split design, while flawed in execution, demonstrated Apple's willingness to address health concerns in the computing industry. The use of Alps SKFS switches represented one of the final mechanical switch implementations in an Apple keyboard before the transition to rubber dome mechanisms.

The keyboard's failure influenced Apple's subsequent keyboard philosophy. Rather than pursue ergonomic designs, Apple focused on reducing key travel and keyboard thickness, culminating in the controversial butterfly mechanism of the 2015-2019 MacBook Pro keyboards. This trajectory suggests that the Adjustable Keyboard's poor reception had lasting effects on Apple's peripheral design strategy.

Ironically, the keyboard has gained appreciation among collectors and ergonomic keyboard enthusiasts decades after its commercial failure. Its rarity and unique position in Apple history have made complete sets increasingly valuable. Modern ergonomic keyboard manufacturers cite it as an early attempt at addressing RSI through design, even if the execution proved flawed.

Design Influence

The Adjustable Keyboard's design elements appeared in various forms in subsequent products:

Split angle concept:

• Microsoft Natural Keyboard (1994) refined the approach
• Kinesis Freestyle series adopted similar split design
• Modern ergonomic keyboards use comparable angles

Separate numeric keypad:

• Influenced modular keyboard designs
• Preceded modern compact keyboard trends
• Demonstrated flexibility in workspace arrangement

Hardware audio controls:

• Became standard on Apple Pro Keyboard (2000)
• Evolved into media keys on modern keyboards
• Established precedent for system-level hardware controls

See Also

• Apple Extended Keyboard II
• Apple Design Keyboard
• Apple Desktop Bus