Apple Design Keyboard
The AppleDesign Keyboard (model M2980) was Apple's first low-cost full-size Macintosh keyboard — full-size meaning a function-key row and a navigation cluster.[1] It replaced the mechanical Apple Extended Keyboard II with rubber domes, and was itself replaced by the Apple USB Keyboard.[1] Deskthority dates its introduction to 1994 and gives the FCC ID as BCGM-2980.[1]
| AppleDesign Keyboard | |
|---|---|
 |
|
| AppleDesign Keyboard M2980 | |
| Manufacturer | Apple Computer, Inc. (NMB, Alps Electric) |
| Type | Computer keyboard |
| Interface | Apple Desktop Bus |
| Compatible | ADB-equipped Macintosh computers |
| Predecessor | Apple Extended Keyboard II |
| Successor | Apple USB Keyboard |
| Model | M2980 |
Most are "platinum" beige; a black version was also made, shipped with the black Macintosh models.[1]
The Four Variants
This is the single most useful thing to know about the M2980: there are at least four distinct internal designs. From the outside they look very similar, but the keycap mount differs between them and the keycaps are not interchangeable, and the number of screw holes on the rear differs.[1] Get this wrong and you will buy a donor whose keycaps do not fit yours.
| Variant | Rear screws | Domes | Keycaps | Other markers |
|---|---|---|---|---|
| NMB dome with slider, "Version A" | 4 | Bright yellow | — | Option keys 1 u; black barrel plate; long, wide rubber feet; white NMB sliders; controller ID "NMB16R2677" |
| NMB dome with slider, "Version B" | 8 | Bright yellow | Shorter, each with a post | Option keys 1.25 u; stepped Caps Lock (1.5:0.25); beige barrel plate; homing keys (D, K, numpad 5) have stems rotated 90°; long, narrow feet |
| Alps dome with slider | 3 | — | Mexico: pad-printed ABS. Czech Republic: dye-sublimated PBT | "Type 2" Alps dome-with-slider; thin metal plate held to the membrane assembly by melted plastic rivets; OEM-profile keycaps, 1.5 / 1.25 / 1.5 / 6.5 / 1.5 / 1.25 / 1.5 u bottom row; Caps Lock slider offset to line up with Tab above it |
| Alps membrane dome | — | Clear, loose | Integrated-mount | Self-contained membrane module screwed to the base; curved black key mounting plate; dome housings identical to the Alps KFRF-1; controller reads "©APPLE, Inc"; 39 screws hold the back of the membrane module |
The three-screws-versus-four-or-eight distinction is the quickest external check: three rear screw holes means an Alps dome-with-slider board.[1]
There is no documented Chinese-built variant. Descriptions of a fourth, generically-sourced "China production" M2980 with higher failure rates could not be corroborated against any photograph-backed source and are not reproduced here.
Cable
Apple's official specification is a fixed cable, and most AppleDesign Keyboards have one.[2] Deskthority records reports of production runs with detachable cables and Alps-compatible sliders, from community threads; it presents these as reports rather than as documentation, and so does this page.[2]
A fixed cable makes strain-relief failure a soldering job rather than a swap, and it is the most common fault on a surviving example.
Construction
NMB variants
White NMB sliders over bright yellow domes, a three-layer membrane, and a controller bearing "NMB16R2677" — which is most of why the keyboard is attributed to NMB at all.[1] The cable is fixed and exits through a moulded channel.[1]
The 90°-rotated stems on the homing keys of Version B are worth noting before reassembly: D, K and numpad 5 will not go back on in the same orientation as their neighbours.[1]
Alps dome with slider
The metal plate is held to the membrane assembly by melted plastic rivets.[1] That is the important detail for repair: there are no screws to undo, and separating the plate to reach the membrane means breaking the rivets. Plan for it — it is a one-way operation, and reassembly needs either adhesive or small screws through the remains.
The stabilising wire is hinged on the keys and slides in recesses in the membrane assembly, not in separate housings.[1] Do not lose the wires; there are no replacements.
The Czech-built boards with dye-sublimated PBT keycaps are the ones enthusiasts look for. The Mexican-built boards have pad-printed ABS, whose legends wear off.[1]
Alps membrane dome
This variant is the odd one out in every respect: a self-contained membrane module that screws to the base, a curved black mounting plate taking integrated-mount keycaps, and clear loose domes rather than a dome sheet.[1] The dome housings are identical to those of the Alps KFRF-1.[1]
39 screws secure the back of the membrane module, applying the pressure that holds the membrane sheets together.[1] If you open one, expect that count, keep the screws, and understand that the uniform pressure they apply is what makes the keyboard work — missing or unevenly tightened screws produce dead keys in patches.
ADB Behaviour
The M2980 is an ordinary ADB encoded device at default address $02.[3]
- Register 0 carries two key events in one 16-bit read.[3]
- Register 2 carries modifier-key status, with 0 meaning down.[3]
- Apple documents no polling rate; in the idle state the transceiver repeats the last Talk command every 11 ms.[3]
- All devices on the bus together must draw no more than 500 mA, with no more than three devices daisy-chained on one port and no more than 5 m of cable.[3]
Unlike its mechanical predecessors this keyboard has a single ADB port, so it is the end of the chain rather than a pass-through.[1]
Maintenance and Repair
Identify the variant first
Count the rear screws and look at the dome colour through a removed keycap. Every repair below depends on which of the four you have, and keycaps and membranes do not swap between them.[1]
Dead key or dead patch
- On the Alps membrane-dome variant, check the 39 module screws before anything else — the module relies on even pressure across the membrane sheets.[1]
- Otherwise open the keyboard and test the membrane traces from the key pad to the tail connector with a meter on continuity.
- A broken trace can be bridged with silver conductive paint. Clean the area with isopropyl alcohol, let it dry fully, build the bridge in thin coats and test resistance before reassembly.
- A whole dead row or column is a matrix line, not individual keys — follow it back to the tail connector, where a partly-seated or corroded connection is the usual cause.
Cable failure at the case
The fixed cable is the commonest fault.[2] Test each conductor for continuity while flexing at the entry point. A splice with heat-shrink and a fresh strain relief restores it; the alternative is desoldering the cable at the PCB and fitting a new four-conductor lead, keeping the pinout.
Liquid ingress
Full disassembly, rinse the membrane in distilled water, then isopropyl alcohol, then dry thoroughly before testing. Inspect for corrosion on the tail connector contacts, which is where the damage usually persists.
Mushy or stiff keys
Hardened or torn domes. On the Alps membrane-dome variant the domes are loose and can be replaced individually; on the others they are part of a sheet and cannot.[1]
Keycaps will not fit
That is the variant problem, not a fault. Keycaps are not interchangeable between the four designs.[1]
What Is Not Documented
No Apple figures for dimensions, weight, retail price, key durability, power consumption, operating environment or production volumes for the M2980 could be traced, and none are stated here. Nor could any source be found for rated dome lifetimes, membrane service life or a failure-progression timetable; such figures circulate widely and are invented. Do not replace parts of this keyboard on a schedule — replace them when they fail.
Restoration
The case is ABS and yellows. Pad-printed legends on the Mexican-built Alps boards will not survive aggressive cleaning; dye-sublimated PBT legends will. See Retrobrite before treating a case.
See Also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 "AppleDesign Keyboard", Deskthority wiki. Part number M2980; FCC ID BCGM-2980; manufacture by NMB and by Alps Electric; NMB dome-with-slider, Alps dome-with-slider and Alps membrane dome switch types; introduced 1994; supersedes the Apple Extended Keyboard II and precedes the Apple USB Keyboard; four documented variants with different keycap mounts (the keycaps are not interchangeable between them) and different numbers of rear case screws; platinum and black colours; the NMB controller ID "NMB16R2677"; NMB Version A with 1u Option keys, black barrel plate, four case screws and long wide rubber feet, and Version B with shorter keys each having a post, 1.25u Option keys, stepped Caps Lock, beige barrel plate, homing keys (D, K and numpad 5) with stems rotated 90°, eight case screws and long narrow feet; Alps dome-with-slider units from Mexico with pad-printed ABS keycaps and from the Czech Republic with dye-sublimated PBT, three rear screw holes, a thin metal plate held to the membrane assembly by melted plastic rivets, OEM-profile keycaps with a 1.5/1.25/1.5/6.5/1.5/1.25/1.5 u bottom row, an offset Caps Lock slider and stabilising wire hinged on the keys and running in recesses in the membrane assembly; and the Alps membrane-dome variant with a self-contained membrane module screwed to the base, a curved black key mounting plate taking integrated-mount keycaps, clear loose domes, dome housings identical to the Alps KFRF-1, a controller reading "©APPLE, Inc" and 39 screws securing the back of the membrane module. Community wiki, cited as a secondary source, photograph-backed.
- ↑ 2.0 2.1 2.2 Apple Computer, Inc., "Extended Keyboard II & AppleDesign Keyboard: Differences", Apple technical information library, cited via Deskthority. Apple's official specification gives the AppleDesign Keyboard a fixed cable. Deskthority records reports of production runs with detachable cables and Alps-compatible sliders, from Geekhack threads, which it marks as reports rather than as documentation.
- ↑ 3.0 3.1 3.2 3.3 3.4 Guide to the Macintosh Family Hardware, second edition, Apple Computer, Inc. / Addison-Wesley, 1990 — hosted on this wiki as File:Apple Guide to the Macintosh Family Hardware 2nd Edition 1990.pdf. Chapter 8, "Apple Desktop Bus": Table 8-1 connector signal assignments (470 Ω pull-up, POWER.ON on pin 2); Table 8-2 transceiver electrical characteristics; Table 8-4 register 0 in the Apple Standard Mouse and its note on 100 ±10 / 200 ±10 counts per inch; Tables 8-7 and 8-8 registers 0 and 2 in the Apple Standard Keyboard; Tables 8-10 and 8-11 registers 0 and 2 in the Apple Extended Keyboard and the $0002 → $0003 Device Handler ID change for right-hand Option and Control; Table 8-13 command byte syntax; Table 8-14 the full ADB timing specification; Table 8-15 device register 3; Table 8-16 device addresses; Table 8-17 reserved Device Handler IDs; the 500 mA total bus limit, the 5 m / 100 pF-per-metre cable limits, the 11 ms idle polling interval and the warning against unplugging a device while the computer is running. Chapter 9, "Floppy Disk Interfaces": Table 9-1 drive capacities, file systems and encoding; the IWM and SWIM interface ICs; internal 20-pin and external DB-19 pinouts; drive current requirements; and the PWM motor-speed line used only by 400K single-sided drives.