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Alps series names and model numbers

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Overview

This page is a general guide to the series and model names of Alps Electric data entry keyboards and switches. As very 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: suitchi), “TACT” switches (タクトス​イッチ: takutosuitchi), and data entry keyboard switches (データエントリー​キーボード​スイッチ: dehtaentorikihbohdosuitchi). 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 Alps however requested that this catalogue not be published on the Internet.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.

Mysteries

The following remain unresolved:

Series names

3-letter series

In the early to mid 1980s, Alps data entry keyboards and switches appear to have 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 1983). Alps keyboard model numbers in the early 80s also demonstrate this practice, e.g. the Alps AKB-3420 is model KCCAA902.

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:

S-types

SCK series is a keyboard switch related to KBB/KCC. This seemingly anomalous series name is not as unexpected as it would seem. The Roland MC-4 internal ten-key pad board (with KEH series switches) has assembly number KEH4A006, which is identical in format to SCH5A031, the original assembly number of the Alps AKB-3420 before it was revised to KCCAA902. That would put Alps KCC/KBB switches in SCH series, bringing it directly in line with SCK series (with H and K being notably close alphabetically). This however muddies the already confusing KBB/KCC quandary even further.

One consideration is that, as “K” seems to be associated with “TACT” switches, “S” may have denoted data entry types. It seems that this distinction was removed at some stage, with data entry keyboard switches being brought into the K family.

However, there is also contradictory information. While the Alps PCB codes for the AKB-3420 and Monroe 2805 are CH54141C and CH34180A respectively, the PCB code for the Olympia CD 102 is also a CH code (something like CH34136B, but it is impossible to read in the photos) and that keypad uses Alps spring bridge switches instead of (S)KCC. This returns us to the previous theory that CH is a non-series-specific code, akin to “12K”, yet at the same time, the correspondence between SCH5A031 and KEH4A006 is clear.

Consequently at this stage, the meaning of “CH” remains unknown, as does “SCH” and any relationship between CH, SCH and SCK.

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.

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 SK__ family, there are these subfamilies (descriptions in quotation marks are verbatim from Alps literature):

Family Type Notes
SKC_ Keyboard switches with what the keyboard community termed “switchplate” contact modules (SKCC, SKCL/SKCM and SKCP)
SKE_ Elastic contact switches — “Tact Switches”: “Metal Contact with LED” (SKEC), “Tact Switches”: “Elastic Contact (Standard Bulk Type)” (SKEY) SKEC as a metal contact switch cannot be verified at present, as it appears to be an obsolete type, and thus there are no online specifications for it; other SKE* types all appear to be elastic contact
SKF_ Keyboard switches with plain metal contacts (thus far, SKFL, SKFM/SKFN and SKFR/SKFS)
SKH_ “Tact Switches”: “Metal Contact (Standard Bulk Type)”, “Metal Contact with LED” (SKHQ, SKHJ), “Mechanical Contact (SMD Type)”
SKP_ “Tact Switches”: “Elastic Contact (Standard Bulk Type)”, “Metal Contact/Soft feeling Type” (SKPL) SKPL is given as “metal contact” in the European catalogue, but the product specification given under the SKPL Series product information clearly shows that it has a dome inside.
SKQ_ “Tact Switches”: “Metal Contact (Standard Bulk Type)” (SKQE, SKQN), “Multifunction Tact Switch” (SKQU), “Mechanical Contact (SMD Type)” (SKQY), “Metal Contact” (SKQR)
SKR_ “Tact Switches”: “Elastic Contact (with LED)”

Switches

3-letter series

The older pattern is not fully understood, and the format is schematic but codes are seemingly specific to families of switch series.

Roland documentation offers a couple of KFL part numbers; sadly no other machines with KFL switches have available service manuals or switch details in these manuals.

The table below includes non-keyboard types, as source data for pattern interpretation.

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
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

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

Kxyabcdd

The positions have the following interpretations in Kxx types (SCK follows a totally different pattern):

x
Thus far, this seems to indicate contact classification (see under newer pattern, below).
y
Series indicator within the above classification (again, see newer pattern, below)
a
This is always a 1 in discovered examples; this column was deleted in the newer scheme.
b
Inner subseries: 0 = normal (replaced with “A”), 1 = LED illuminated (replaced with “F”), 2 = incandescent illuminated, 5 = vertical (replaced with “L”)
c
This is either 0 or 9 in discovered examples; generally 9 is the default value, with 0 being the first alternative variation (e.g. 2-unit versus 1-unit keycap). This position is not well understood.
dd
Generally this is the sequence number within the series or subseries. For standard keyboard switches, 3 is a common value, for a reason yet to become clear. Only one example has been found greater than 09, namely KEC10010, and so far it is impossible to understand the details of KEC from the only photo available.

Subseries

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:

SKxyza

The positions have the following interepretations:

S
Switch
K
Single-key switch
x
Thus far, this seems to indicate contact classification when it comes to keyboard switches; see series families above.
y
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)
z
Subseries, covering a particular set of characteristics (see below)
a
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).

Subseries

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
SKCCAF SKCCAF002A (1987)
SKCCBJ SKCCBJ0001
SKCCBK SKCCBK0001
SKFRAC SKFRAC000A (1999)
SKFSAA SKFSAA000A (2004)
SKPAAA SKPAAA000A (200?)

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

Series

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

Kfssvv

The positions have the following interepretations:

K
Keyboard
f
Form; only known thus far as “F” for “full keyboard” (presumably as opposed to external numeric keypads)
ss
Switch series, last two letters, e.g. “FL” for a keyboard with SKFL switches
vv
“Product structure and variety”, such as “AB” or “EA”

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:

Kfssvvcccc

cccc
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”.

Documentation