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Alps series names and model numbers



This page is a general guide to the series and model names of Alps Electric data entry keyboards and switches. As little official data has been recovered, a complete understanding is not yet possible. Some product range details remain a mystery.

Alps distinguished between at least three broad types of pushbutton switch: switches (スイッチ), “TACT” switches (タクトス​イッチ), and data entry keyboard switches (データエントリー​キーボード​スイッチ). The latter was divided into “mechanical contact” (in 1994, SKCL, SKCM, SKFR and SKFS) and “full-stroke membrane” (in 1994, KFNR and KFNY). Full-stroke membrane switch types had their own series, even though they did not come as discrete switches; these series names did however begin “KF” for “full keyboard”.

Alps revised the series naming system at least once, if not several times, so some series have more than one name following renaming exercises. In particular, the most common family of all—SKCL/SKCM—was previously KCL and KCM, then SKCL and SKCM.

Some information here is taken from the Alps ’94 Keyboard Switches (キーボードスイッチ) catalogue, which was kindly provided by Sandy. Alps however requested that this catalogue not be published on the Internet. The Alps keyboard codes list compiled at the Deskthority wiki contains additional information. The non-keyboard part data page lists Roland and Yamaha service manual findings, which includes many Alps switch model and part numbers.


The following remain unresolved:

Series names

AK codes

The oldest-known keyboard and switch codes begin “AK”, and include:

AKC8N and AKC8S however are types that would likely fall under KH_, with AKC8N at least somewhat resembling KHC Series. AKE-1 is an elastic contact type that resembles KEF Series. There are not enough details to be clear on the series correspondences, but we can certainly see that AK types covered a similar spectrum to the later K types. The reorganised codes dropped the “A” (for Alps?), reducing the significant character count by one.

3-letter S groupings

Three-letter S groupings apppear to have run in parallel to the AK codes. With these codes, it is not entirely clear whether they are classification codes or series names. The PCB codes tend to be the second and third letters, e.g. the SCB PCB discovered has a “CB” code, and the SCH PCBs have “CH” codes. However, there are also “spring bridge” keypads whose PCBs have “CH” codes (CH34149B with metal-top AKC series switches, and plastic-top switches in a PCB code that may read “CH34136B”), offering the possibility that SCH covers more than one series. The amount of examples discovered to date is insufficient to get a clear example, and we know that Micro Switch would share parts between related series. Examples so far include:

Code Switches Examples
SCB Reed SCB1A163 keyboard chassis (1973 or 1974; PCB code CB14182B)
SCF Reed NEC DT-KCD2000C Type A keyboard chassis (1975; NEC PCB)
SCH KCC Alps AKB-3420 (model SCH5A031, revised to KCCAA902; PCB code CH54141C)
Monroe 2805 (PCB code CH34180A; ca. 1979)
SCK “SCK” SCK series (similar to KCC but with a lost motion hysteresis actuator; in existence by 1979)

Purely from the examples found to date, SCB and SCF have denoted reed switches, SCH has denoted mechanical switches, and SCK has denoted mechanical switches with hysteresis.

The model numbers are in the same format as that used with separate series names. The original model number of Alps AKB-3420 was SCH5A031, which is identical in format to the model of the Roland MC-4 internal ten-key pad board, of KEH4A006 (which uses KEH series elastic contact switches); in “KEH4A006” the “4” denotes 9-12 keys, with no definition found for a “5” in this position. The SCF example has model number SCFAB077, which visually matches the K-era format, with position four changed from numeric to alphabetic.

The patent for Alps spring bridge switches was filed in 1972 (1973 in the US), and similarly the SCB reed keypad is from late 1973 or early 1974. This gives some indication of the age of this model number system.

An Olivetti typewriter keyboard made by Alps has PCB code CN54114B. The same Alps-made switches can be seen in a video of the Olivetti ET 121 typewriter keyboard, while the switches are shown to be covered by US patent 4200778 “Electric keyboard of snap-contact type” filed by Olivetti in May 1978 with priority to a May 1977 Italian patent. There is neither a date nor a keyboard assembly model present.

Note that these codes should not be confused with the S series of products that appear to have been contemporary with the K series, including the signal selector switches (SUJ, SUN, SUL etc), rotary BCD and hexadecimal number selector switches (SRQ), SUT double pole switches and SDS, SDU and SDW power switches.

3-letter K series

In the early to mid 1980s, Alps data entry keyboards and switches appear shared the same series name. These series names were all three letters long and began with “K”. This can be seen in an Alps Electric (USA) advertisement in Electronic Engineers Master 83–84 which mentions “Series KFL Low Profile Keyboards” (confirming the existence of KFL in 1983). Alps keyboard model numbers in the early 80s also demonstrate this practice, e.g. Alps AKB-3420 became model KCCAA902. The KFL model number (KFLAA004) can be seen in the label on the Canon A-1110 keyboard PCB.

Many series names were recovered from Roland documentation (as switch model numbers) and Apple technical literature (without model numbers). The following data entry keyboard and switch series are known:

4-letter and 6-letter series

In the mid-80s, Alps converted from three-letter to four-letter series names. This can be seen from Roland service manuals, as they were introducing new models each year, and used Alps switches extensively; the new series names first appear in 1985. In the process, model numbers were reduced from seven to six digits. For example, KHC10902 is reported to have changed to SKHCAB and thence to SKHCBEA010.

In the process, switches and keyboards were split into separate series. Keyboard switch series simply gained an initial “S”, where the original “K” now denoted a keyboard switch. Keyboards gained new series names beginning “K”, typically followed by “F” for “full keyboard”; these series names were six letters long and covered not just the size and switch series but additional details such as whether an enclosure was fitted or whether a microcontroller was included. The two letters that distinguished the series (e.g. “FL” or “CM”) were included in both the switch series name (e.g. “SKCM”) and keyboard series name (e.g. “KFFLEB”):

Alps did not specify any further details on the formation of series names.

Keyboard model numbers can also be seen to have changed in format during the mid 80s, from the old format (e.g. KFFBA010) to the new format (“KFFLEB004C”). In the case of the AKB-3420, the model number KCCAB902A gained only the “F” to become KFCCAB902A, remaining otherwise unchanged, in contrast to switches which changed format completely.

Keyboard switch series with confirmed or tentatively confirmed four-letter names include:

Note that membrane types use “KF” (full keyboard) instead of “SK” (key switch) as they are not discrete types; the series names describe the switch technology rather than separate parts.

So far, it is not known how many series were renamed: some may have been end-of-life at the point that the new names were introduced, or in extended lifetime only (manufactured but no longer advertised), and Alps may not have retrospectively renamed them.

The following keyboard switch series have confirmed new-style part numbers, but no literature has been found that shows the series names:

SKPA is recent enough to be considered as affirmed, however.

Keyboard series with six-letter names include:

2-letter series

At some point between 1985 and 1989, Alps produced a sample card on which they wrote “Mechanical Contact with Tactile CM(KCM) Series” against models SKCMAF (ivory tactile) and SKCMAG (blue). By “Tactile” they appear to have meant “Tactile Feedback” or “Tactility”, i.e. they are not referring to a “tactile CM”. (If the card had also been labelled in Japanese then this could have been confirmed.) The meaning of “CM” and the distinction between “CM” and “KCM” is not clear, but it appears that “CM” is an abbreviation. The 1994 Alps catalogue uses this abbreviated form in at least one place, as well as “SKCL/CM Series” (also given in Japanese as 「SKCL・CMシリーズ」), which is contrasted with “SKFR/SKFS Series” from the paragraph above (in Japanese, 「SKFR, SKFSシ リーズ」, with “, ” instead of “・”).

Previously it was believed that the 1994 Alps catalogue also used “CM Series” and “CL Series”, but this was a result of miscommunication over the transcription of the document. The 1993 catalogue and 1994 catalogue do both say “SKCL Series” and “SKCM Series” as one would have expected.

A Curved Full Keyboard advertisement in JEE (Journal of Electronic Engineering) in 1986 includes the following text:

The CM seried [sic] features sharp clicking, the CL series provides soft touching and the CP series, with hysteresis characteristics is used for high-speed keying. They meet DIN standards with a low-profile, total height of 18.1 mm and 3.5 mm key travel

This is another example of the abbreviated series names. This practice may have only started after the switches and keyboards were split into separate series, as a way to refer to the keyboards (e.g. KFCL) and switches (e.g. SKCL) collectively; curiously (as seen with “CM(KCM)” versus SKCMAG/SKCMAF), the old K names persisted into the SK/KF era.

Series families

Based on Alps EUROPEAN SELECTION 2000/2001, switch series names are generally four letters long, beginning with S, with the following families:

Family Type
SS__ Slide switches
SP__ Push switches
SR__ Rotary switches
SK__ “Tact Switches” (formerly including keyboard switches)

Within both the K__ and SK__ families, the switches are grouped by contact type (most details as per an Alps Keyboard Switches No. 1 catalogue from the 1980s):

Family Type Notes
KC_/SKC_ “Diaphragm” contact (ダイアフラム接点), a term possibly take from Datanetics) The diaphragm assembly is what became known to enthusiasts as the “switchplate”
KE_/SKE_ Elastic contact switches Colloquially known as “integrated dome” as each switch contains a single rubber dome
KF_/SKF_ “Leaf Spring” (イタバネ接点: “Itabane contact”) Keyboard switches with plain metal contacts (e.g. KFF, KFL)
KG_ Reed switches Not confirmed to have survived past the mid 1980s
KH_/SKH_ “Circular leaf spring” (円形板バネ接点) Likely to be TACT switches only
KJ_ “Cylinder key switch”
KK_ Capacitive keyboards
KN_/SKN_ Full-travel membrane keyboards
SKP_ Appears to be an overflow continuation of SKE_
SKQ_ Appears to be an overflow continuation of SKH_
SKR_ “Tact Switches”: “Elastic Contact (with LED)”


3-letter groupings

In three-letter series, keycap size is set in the centre digit, and switch type in the last digit or two. Here, the digit meanings are completely different, indicating that the numbering system is quite different to three-letter series system.

Part Series Type Source
SCK41167 SCK Momentary, with 1-unit relegendable keycap Roland CSQ-100 and CSQ-600 service notes
SCK41168 SCK Momentary, with 2-unit relegendable keycap Roland CSQ-100 and CSQ-600 service notes

3-letter series

The Keyboard Switches No. 1 catalogue found on the CASA Modular Systems website provides an overview to this numbering system. Sadly, only the first 12 pages were included, omitting the entire section on keyboard switches.

These codes are schematic, but the positions of the digits is not yet clear. The general pattern is as follows:


The positions have the following interpretations:

“Keyboard Switch” (キーボードスイッチ); note that these numbers are also used for full keyboards.
Contact classification, as noted above; officially “Type of Contact” (接点構造区分: “contact structure classification”).
Series indicator within the above classification (see under newer pattern, below); officially “Switch Type” (スイッチ構造区分: “switch structure classification”).
Officially, the number of keys: 1 = 1 key, 2 = 2–4 keys, 3 = 4–8 keys, 4 = 9–12 keys; for keyboards, this position is a letter instead, typically “A” or “B” (e.g. KCMAA001, KFFBA010)
Switch type (officially 特殊機構区分, “Special mechanism classification”): 0 = normal (replaced with “A” in the 4-letter series system), 1 = LED illuminated (replaced with “F”), 2 = incandescent illuminated, 3 = alternate action (replaced with “J”), 4 = double action (replaced with “K”), 5 = special mounting (replaced with “L”). For keyboards, this position is a letter also.
“Serial Number” (通しNo.) Standard models have “9” in the first position. Other models typically have “0” in the first position and indicate a change to the design; such types can be found in catalogues. For keyboards this seems to distinguish between stock models (e.g. KCCAA902 for the Alps AKB-3420) and customer-specific designs.

Some examples:

Part Series Type Source
KCA10037 ? Momentary From the Roland CR-78 service notes; this switch has yet to be seen
KCC10903 KCC Momentary Yamaha QX1 service manual
KED10001 KED Momentary, with 2-unit relegendable keycap Roland TR-808 service notes
KED10903 KED Momentary, with 1-unit relegendable keycap Roland TR-808 service notes
KEH10903 KEH Momentary Roland MC-4 service notes
KFL10903 KFL Momentary Roland SBX-80 and TR-090 service notes
KFL11904 KFL Momentary illuminated Roland SBX-80 and TR-090 service notes
KHH10908 KHH Momentary (non-keyboard) Yamaha QX3 service manual
KHJ10902 KHJ Momentary (non-keyboard) Roland SBX-80 service notes
KHJ11901 KHJ Momentary illuminated (non-keyboard) Roland SBX-80 service notes


There are at least two subseries patterns.

Outer subseries groupings combine multiple series together. For example, standard-size tact switches were divided as follows, according to the switch operation:

Inner subseries used the second digit for the grouping. This led to terms such as “KEF10 Joint Series”, which the non-illuminated KEF series (KEF10) variants with a “joint stem”, i.e. with a keystem instead of a flat slider. In some cases it seems like the codes are split even/odd by keystem, but presently insufficient information is available to be certain.

4-letter series

Newer pattern model numbers take the form:


The positions have the following interepretations:

Single-key switch
Thus far, this seems to indicate contact classification when it comes to keyboard switches; see series families above.
Series indicator within the above classification, such as “B”, “C”, “L”, “M” and “P” within SKCy; these are often paired, with the linear type having the lower of two adjacent letters (SKCL/SKCM, SKFM/SKFN, and SKFR/SKFS)
Subseries, covering a particular set of characteristics (see below)
Individual switch model letter; this last character remains a complete mystery. In some subseries, it starts at “A” (such as SKFSAA or SKFNAA) while with other subseries the earliest character is at least a few letters in (as with SKFRAC, the lowest known SKFR model, and SKCLJC, the lowest SKCLJa type, and it’s never clear whether all subtypes started at A or whether some subseries skipped the first few letters).


In this schema, with keyboard, outer subseries were used for linear versus tactile: SKCL/SKCM, SKFM/SKFN and SKFR/SKFS, with linear coming first in each pair.

Other characteristics use inner subseries. It seems that some subseries letters (in particular F) are shared between more than one series. The explanations given below relate to this schema as it applies to keyboard switches, but some application to other pushbutton switch types is also noted for clarity.

Subseries Example meanings
A The initial design variant of the switch is denoted “A”. In all keyboard switch examples to date, “A” covers single-pole, single-throw normally-open momentary switches. In SKCC series, it appears to indicate switches with a tall slider.
B “B” denotes the first alternative design variant (e.g. through hole versus surface mount). In SKCM series, it appears to denote damped (SKCMBB: SKCM Cream Damped), while in SKCC series, it appears to denote standard slider height.
C The only known example in keyboard switches is SKCMCQ, which seems to be a replacement model number for white Alps (SKCMAQ); it seemed like “C” might denote bamboo switches, but as SKCM Green model SKCMAT seems to be bamboo, the meaning of “C” and the difference between SKCMCQ and SKCMAQ remains a mystery.
F In all examples to date, this indicates an illuminated switch. This is SKCLFQ (SKCL Yellow with red LED) and SKCLFM (SKCL Yellow with green LED) from SKCL series, and SKFRFA (red LED), SKFRFB (green LED) and SKFRFC (amber LED) from SKFR series. Non-keyboard series such as SKEC also follow this pattern.
J Alternate action (SKCLJC: grey Alps Lock)
K Double action (SKCLKB)

Additional letters found in non-keyboard series include:

Subseries Example meanings
G Tentatively, G is to F, what B is to A: an alternate form factor of illuminated switch.
L This seems to denote a vertically-orientated switch.

Other letters are known from non-keyboard switches, but additional research would be required to identify patterns.

Control numbers

Complete switch part numbers include a four-digit Alps “control number”. For keyboards, the control number is part of the model number. For switches, the meaning is undefined, but may also denote product variations accordingly. Control numbers are typically three digits followed by a letter (e.g. 001A) but they can also be four digits (e.g. 0001) or (especially with 1980s keyboards) three digits (as in model KCCAA902 used on the Alps AKB-3420). All the following part numbers are taken from official Alps or Forward Electronics switch packaging, with the years given where known:

Model Part

It appears that current practice abolishes model numbers and uses only part numbers, with a control number that begins with a letter instead of ends with a letter, e.g. “SKECADA010”.



Keyboards originally shared the same series as the switches they used, including the same part number style. From the mid 1980s onwards, they were split out into new series, with names in this format:


The positions have the following interepretations:

“Full keyboard”
Switch series, last two letters, e.g. “FL” for a keyboard with SKFL switches

Documentation for the form position has yet to be found. However, broadly, the form position seems to follow this pattern:

Code Form
A Complete internal keyboard module with controller, for fitting into a case or computer
B Internal keyboard module with no controller, intended for use inside a computer with its own controller
D Unknown difference from B; from Canon AP 810 keyboard module KFCMDA036 (PCB 12KC691A)
E Fully-enclosed keyboard for connecting to a computer (e.g. AT, PS/2)

The Toshiba T3200 keyboard module does not fit this pattern. Its assembly number is KFFLEB004C, indicating a full keyboard (“KF”) that is external and fully enclosed (“E”) with SKFL switches (“FL”). Instead, it is an internal module with no controller. It does have part of an enclosure, which may count, although this could be an error on Alps part. Normally such an assembly would be of form “B”.

There is not enough information yet to understand what the “variety” position covers.

Model numbers

Keyboard model numbers make use of the Alps control number extension codes. For example, the Panasonic Business Partner 286 keyboard is model KFCMEA015A, in series KFCMEA. This confirms that Alps “Bigfoot” keyboards are not series KFCMEA and KFCLEA, as these series simply contain standard keyboards with SKCL and SKCM switches.

The keyboard model number format is as follows:


Alps control number: three digits optionally followed by a letter

The format is identical to that of the keyboard series, except for the addition of the four-digit control number. Control numbers whose digit groups are in the 900 range denote standard products. The Panasonic Business Partner 286 keyboard has control number 015A, suggesting a custom part. By comparison, the Alps SM-101 buckling spring keyboard is model KFNLEA901 has control number 901, indicating that it is a standard off-the-shelf model, which it is (used by Sega, RM and C-Itoh).

Gold Star Alps

Two of the rarest Alps switches are SKCL Brown and SKCL Amber. These were found side-by-side in a Packard Bell KCLEA907L keyboard manufactured by Gold Star Alps in Korea. The PCB code is 12KC619BK, with a final “K”. SKCL Brown was also used in the almost identical Packard Bell KFCLEA916A (PCB code 12KC618A).

A similar keyboard, BIOS Express KCME907L, was also made by Gold Star Alps in Korea, with the same PCB code as for KCLEA907L; this has SKCM Blue switches.

It is interesting to note that another example of SKCL Brown occurs in an unidentified Visual Technology keyboard; here, the PCB code is 12KCA10AK.

It seems likely that the final “K” in the PCB code stands for “Korea” and indicates that the keyboard to which it belongs was made by Gold Star Alps, and that for whatever reason, Gold Star Alps SKCL switches were a different colour to Japanese SKCL switches. Whether this is because they had different pigmentation available, or because the switches were specified differently, remains a mystery, as no force curves are known to exist for these switches.

Interestingly, the latching switch colour follows that of the normal key switch (brown), instead of the space bar switch (amber), as seen in some unidentified keyboard, of which nothing else is known at the time of writing, except that the serial number ends in “K”.