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Apple Adjustable Keyboard

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Revision as of 12:25, 30 September 2026 by Josh (talk | contribs) (Rewrite: cite TidBITS Jan 1993 (30° split, keypad on ADB cable, sound keys, US$219); ADB section now uses sourced handler IDs ($10/$0E) and the address-7 sound-button device instead of uncited collision/troubleshooting claims; Family Hardware p. 287/292 for bus limits; release_date param fixed; remove uncited claims (travel myths, lubrication, Retrobrite advice))
Apple Adjustable Keyboard
Apple Adjustable Keyboard M1242 with its separate keypad (wrist rests removed)
Manufacturer Apple Computer, Inc.
Type Ergonomic split keyboard
Release date 1993
Price US$219 (announced list price)
Interface Apple Desktop Bus
Compatible ADB-equipped Macintosh computers, including PowerBooks
Weight 1,005 g (keyboard), 372 g (keypad)
Model M1242

The Apple Adjustable Keyboard (model M1242) is Apple's split ergonomic keyboard for ADB Macintosh computers, introduced in 1993.[1] The two halves are hinged at the centre rear and swing apart horizontally, up to 30 degrees, with the 6, Y, H and N keys on the right-hand half. The enlarged space bar stays fixed in the centre.[1][2] The keyboard came with removable wrist rests, one for each half, and a separate keypad with its own wrist rest.[1]

The keypad holds the function keys, the navigation cluster and the numeric keys, and connects to the keyboard by a short ADB cable. It can sit on either side of the keyboard.[2] The main keyboard has volume, mute and microphone-record buttons on its right-hand half, the first Macintosh keyboard with sound controls; Apple's software for them needed System 6.0.7 or later. The Escape key, the sound buttons and the function keys are small round keys.[2] TidBITS reported an expected list price of US$219.[2] The FCC ID is BCGM1242 and the layouts are modified ANSI or ISO.[1]

Switches

Main keys

The alphanumeric keys use Alps SKFS switches, from the low-profile PCB-mount SKFR/SKFS series.[1] Although low-profile, the switches have the full 3.5 mm travel. The switch is 10.3 mm tall and has an integrated jumper. Its keycap mount is unique to the series, not the common Alps mount, and it is neither pin- nor keycap-compatible with Alps SKFL, so Alps-mount keycaps do not fit and an SKFL is not a substitute.[3]

The variant fitted is SKFS White, Alps model SKFSAA, the tactile member of the series. Its click leaf sits in front of a chamber with an open front wall, so when released the leaf strikes nothing and the switch does not click.[3] The 1994 Alps catalogue nonetheless lists SKFS as clicky.[1]

Function keys and navigation cluster

The function keys and the upper navigation cluster on the keypad are round buttons over what appear to be simple microswitches.[1] TidBITS questioned at launch whether these harder-to-press keys suited an ergonomic keyboard.[2]

ADB devices

The keyboard and the keypad are separate ADB keyboard devices on the same bus. The keyboard reports Device Handler ID $10 (ANSI), $11 (ISO) or $12 (JIS); the keypad reports $0E.[4] Keyboards default to ADB address $02, and when two devices share a default address the Start Manager gives one of them a new address at startup.[5] The four sound buttons are a third device, at ADB address 7, which the Linux driver lists as the "Adjustable keyboard button device" (original handler ID $02) with microphone, mute, volume-down and volume-up events.[4][6]

Apple's bus limits apply to the set as a whole: all ADB devices together may draw no more than 500 mA, cables should be no longer than 5 m, and Apple does not recommend daisy-chaining more than three devices on one ADB port.[7] Do not unplug and reconnect an ADB device while the computer is running: the device reverts to its default address while the computer keeps using the address it assigned at startup.[5]

Maintenance and repair

The keyboard and the keypad are separate assemblies with their own PCBs.[1] Because each is its own ADB device, test them one at a time, each connected directly to the computer, to find which unit is at fault.

Wrist rests

The rests are removable by design. A complete set is three: one for each half of the keyboard and one for the keypad.[1]

Dead or chattering main key

  1. Remove the keycap carefully. The SKFS keycap mount is unique to the series, so a broken keycap or stem cannot be replaced from another Alps family.[3]
  2. Clean the switch with isopropyl alcohol, actuate it repeatedly and let it dry fully.
  3. If that fails, the switch must be desoldered and replaced with another SKFS. Donor Adjustable Keyboards are the usual source; new-old-stock SKFS switches have been sold through online surplus sellers.[3]

Keypad or sound buttons not working

  1. Connect the keypad on its own. If it works alone but not in the chain, check the ADB cables and shorten the chain.[7]
  2. The sound buttons need Apple's software (System 6.0.7 or later) on the Macintosh,[2] and on modern systems a converter or driver that reads the button device at address 7.[4]

Modern use

An ADB-to-USB converter has to handle more than one keyboard device on the bus to make the keypad work, and must read the address-7 button device for the sound keys.[4] See Apple Desktop Bus for the protocol.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Deskthority wiki, "Apple Adjustable Keyboard": part number M1242, FCC ID BCGM1242, modified ANSI or ISO layouts, Alps SKFS switches and microswitches, PCB mount, ADB, weights 1,005 g (keyboard) and 372 g (keypad), introduced 1993; description of the hinge, space bar, wrist rests and keypad; photographs of both PCBs. Community wiki, secondary source. Retrieved 2026-09-30.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Adam Engst, "Apple Adjustable Keyboard", TidBITS, 11 January 1993: opening angle up to 30 degrees, split with 6, Y, H and N on the right, fixed enlarged space bar, detachable palm rests, separate extended keypad on a short ADB cable for either side, round keys for Escape, sound and function keys, volume, mute and microphone controls, expected list price US$219, ADB Macs and PowerBooks, sound-key software for System 6.0.7 and later. Retrieved 2026-09-30.
  3. ↑ 3.0 3.1 3.2 3.3 Deskthority wiki, "Alps SKFR/SKFS series", with part numbers from the 1994 Alps catalogue: 3.5 mm travel, 10.3 mm height, integrated jumper, unique keycap mount, not compatible with SKFL; SKFS White (SKFSAA) tactile, with photographs of the switch from an Apple Adjustable Keyboard and of NOS switches. Retrieved 2026-09-30.
  4. ↑ 4.0 4.1 4.2 4.3 TMK keyboard firmware wiki, "Apple Desktop Bus", "Keyboard Handler ID" (Apple Adjustable Keypad M1242 0x0E; Apple Adjustable Keyboard M1242 0x10, ISO 0x11, JIS 0x12) and "Apple Adjustable Keyboard Media keys" (volume up, volume down, mute and microphone from appliance address 7). Retrieved 2026-09-30.
  5. ↑ 5.0 5.1 Apple Computer, Guide to the Macintosh Family Hardware, 2nd edition (1990), chapter 8, "Apple Desktop Bus", p. 287. Hosted as File:Apple Guide to the Macintosh Family Hardware 2nd Edition 1990.pdf.
  6. ↑ Linux kernel, drivers/macintosh/adbhid.c, ADB_MISC handler 0x02 "Adjustable keyboard button device". Retrieved 2026-09-30.
  7. ↑ 7.0 7.1 Guide to the Macintosh Family Hardware, 2nd ed., p. 292.


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