Jump to page content

Keyboard–switch database Keyboard details


There are multiple ways by which keyboards can be dated. Within Keycombo, as many of these dates are recorded as possible, in part because they can be misread, and in part to increase the amount of data available.

Typically, only one or two types of dates will be found on a single keyboard, if indeed there are any dates present at all.

Date format

In many cases, the date is in the form of the year and the week within the year. Typically this is four digits; e.g. “9045” means the 45th week of 1990.

Cherry date codes use a letter for the year, e.g. “C45” means the 45th week of 1990 (“C”). See Cherry date codes on the Deskthority wiki for a full list of year letters.

It appears that Mitsumi’s full eight-digit “price label” stickers might reverse the order, with the above date being printed as “4590”. The year appears certain; the two preceding digits are not guaranteed to indicate the week.

Sources

The different date sources are illustrated in detail below. Because Keycombo cannot sensibly understand every possible type of date code, I use a certain amount of discretion, such as using the label on a Mitsumi membrane backplate as a “PCB” date, or the date on a circuit component that is not a microchip, as an “IC” date.

Label

The most readily accessible date source is the label on the back of the keyboard. The date may take various forms: Cherry use cryptic codes, some brands place the date into the serial number, and in some instances the manufacture date is written in full.

IBM makes it easy for you — the date is written on the label
Another full date, on a Viglen 6312 (Acer OEM)
A Cherry date code: R11 is the 11th week of 2005
Tulip serial numbers appear to contain the year (here, 1990)

Case moulding

The next best date source is the case moulding. Case mouldings provide unambiguous, easily readable dates.

Wheel-style dates on a Datacomp DFK-192, indicating August 1991
Punch grid–style dates on a Mitsumi-made Apple Keyboard II, indicating April 1991

Integrated circuits

Most modern keyboards contain at least one integrated circuit, the microcontroller (computer on a chip) that drives the keyboard. Older keyboards in particular typically have additional support chips. Many of these chips bear a manufacture date, typically in the four digit year-week format. Unfortunately, the date codes often feature extraneous (for our purposes!) letters, while a lot of product codes also contain exactly four digits. The best example of misleading codes is Ortek’s microcontrollers, which contain unrecognisable codes that in most cases are fairly plausible date codes: the first two digits being a reasonable year, and the second two digits seldom exceeding 52. For example:

P8049AH 8731
ORTEK 91
101SX-4
INTELⓂ©1977

Here, P8049AH is a variant of the Intel MCS-48 microcontroller family, and 101SX-4 is the type of keyboard. “8731” is a plausible year-like code, but does not have a recognised meaning. “ORTEK 91” appears to give the year of production as 1991; for the purposes of this database, this is what I take to be the year. The copyright date for the microcontroller hardware (here, 1977) is usually much older than the keyboard!

In cases where the controller chip is a PROM or EPROM with a paper label, or where it is hidden from view, the dates on the support chips are second best. It could be argued that these dates are at risk of being older, due to large batches of these commonplace chips being stockpiled, but I couldn’t really say.

“9106”: 6th week of 1991 (Mitsumi-made Keyboard II)
“9122”: 22nd week of 1991 (DFK-192)
Neve Necam 96 keyboard
NTC KB-6251 controller with various four-digit codes, and the date code highlighted: “9031” for 31st week in 1990

In the case of the Necam 96 keyboard, the controller chip (bottom-left in the photo) has a paper label, so I’m going by the dates on the other chips. Note the chip on the right that reads “D8251AFC” in large type, and “8444K8“ in small type: it stands to reason that 8444 is the date code, as that would make it consistent with the other chips. D8251AFC appears to be an NEC programmable interface controller.

In some cases, the controller chip has no date code at all, such as on my SMK-made Tulip ATK 03.01.44. Care needs to be taken when attempting to isolate the date code: always consider whether the alleged year would be reasonable, and check whether the dates on the various components appear to be consistent with each other.

PCB

Keyboards typically contain at least one printed circuit board; this is true even of rubber dome over membrane keyboards. In some cases, the PCB is dated by way of etching or by a paper label. Four digit week-year codes can be found especially on Hi-Tek/NMB keyboards. Mitsumi use their “price sticker” labels that give just the year (in six-digit form), or possibly the week and year (eight-digit) codes.

Mitsumi “price label” sticker from a Keyboard II; the 1991 date is visible (“__91____”), preceded by what is possibly week 50
BTC 5149 PCB with a typical 7-segment year–week code
Dell SK-8115 keyboard with a 7-segment code on the controller board
Apparent revision date on a DFK-192: in this case, it does correspond with the IC and case codes

Be aware that many PCBs also bear a copyright year; this is the year that that the circuitry was designed, and is not necessarily the year that the keyboard was made. In the case of Chicony, whose PCBs typically name the switch type used, drop-in replacement switches (e.g. Aristotle for Cherry MX) may not result in a new PCB being drawn up.

Product

If all else fails, sometimes the only option is to cite the range of years that a product was known to have been made. For example, the Canon Cat was only manufactured in 1987, so Jayson Elliot’s SMK keyboard example must be from 1987. The product year can be specified either as the date of introduction (e.g. the Apple M0110 keyboard was introduced in 1984 as part of the Macintosh) or the full date range (e.g. 1987-1987 for the Canon Cat keyboard).