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Updates for 2020


Friday, 27th March

Although a few Raytheon keyboards are known, it appears that there is only one discovered example made by Raytheon themselves, using reed switches (the others were made by Cortron). Meryl Miller collected a sample switch at the end of the 70s or early 1980s that appears to be Raytheon — I could have had it and would have had it if I had realised it was a keyboard switch (likewise his Fujitsu FES-2 and Micro Switch 1PB870 and KB types).

A new Raytheon page collects together what little is known about Raytheon’s keyboards and switches, including a single photo of Meryl’s type and a diagram showing how it appears to work, based on his photograph and a patent for an older design.

Thursday, 12th March

At the end of the 1960s and the start of the 1970s, manufacturers were finding a surprising number of ways to design switches that could directly address logic circuitry without contact bounce. The earliest known dedicated bounce-free keyboard switch type was Micro Switch SW using Hall effect, introduced at the end of 1968. Licon put out Series 550 ferrite core (“magnetic valve”), that goes back at least as far as the end of 1970. Perhaps the strangest was Mechanical Enterprises Mercutronic, a family of designs that used mercury-containing tubes for switch contacts, available for keyboard applications from around 1970.

RAFI used Hall effect from around 1973, in the form of RC 72 series. This was not their original contactless switch: an older design is known from patents, using magnetoresistance, that has yet to be encountered. Fortunately RAFI still have a 1972 catalogue documenting these switches. RAFI magnetoresistive switches appear to have no series name, only part numbers; they are described simply as “contactless”.

These may well not be RAFI’s oldest keyboard switches, but this is the oldest catalogue that RAFI were able to find, and both this and the RC 72 catalogue defied the odds against being recovered.

Wednesday, 11th March

RAFI have now scanned in for me the complete RAFI-System 72 (RC 72) catalogue. The catalogue was printed in 1983, which explains why the Hall sensor characteristics relate to later Siemens models (models seemingly not in existence when the switch series was introduced). The catalogue includes a diagram of the internal structure of both the Hall and mechanical types, and from this it is clear that this is indeed the annular-magnet type from the patent filed in 1972, which ties in with RAFI’s unclear indication that these switches were introduced in 1973. Jacob Alexander’s example will thus be a redesigned version. Two more switch types can now be seen: RC 72 N mains power switches, and keylock switches.

All we need now is details of RAFI’s original switches, which appear to have been magnetoresistive.

Friday, 6th March

Fujitsu FES-1/FES-2/FES-3 now has a page of its own, on which the original specifications and part number format is now documented, as per the Fujitsu magazine scans previously provided by Kiyoto. Curiously these are in a totally different format to the numbers found stamped on FES-1, FES-8 and FES-9 reed switches.


Tuesday, 25th February

Research has already shown that Micro Switch SW began life with an older plunger design moulded from grey plastic. These older switches can be seen in advertisements, but they have not been otherwise encountered. All discovered SW Series switches had model numbers from 1SW11 upwards; however, model number 1SW1-R can be found on various part listing sites, albeit without any photographs or other evidence. It stood to reason that 1SW11 upwards was the circa 1970 redesign (with black plungers) and 1SW1 upwards was the original 1968 design (with grey plungers).

Finally, visual proof of early 1SW1 has arrived, in the form of a “3D model” of an unidentifiable SW Series keyboard, manufactured around 1969 judging by the dates on the switches. The switches are (surprisingly, for a keyboard that old) marked with their part numbers, with all visible markings being of model 1SW1 from week 26 of 1969. This is the oldest SW Series keyboard found to date. The model label is present but the stamped inscription is either absent or missing from the model; the only visible identifying code is that of the PCB, catalogue listing SW-10033.

This is not proof that 1SW1 was the older-style switch; photos of the next-oldest known keyboard do not appear to show whether those switches were stamped or not, and thus we cannot determine yet whether this is when the part numbers changed. The part number change could have instead corresponded to a change of some other characteristic, such as a redesign of the Hall sensor. As always, more evidence is still required.

Monday, 10th February

In October 2019, Deepak Kandepet introduced me to an unknown reed switch type, depicted as switch 2 in a gallery of then-unidentified switches. This type is always marked “ПКМ 1Б” (“PKM 1B”). Some investigation found that some were also marked with a logo that somewhat resembled a smiling face. Later, I came across the Russian Virtual Computer Museum. Armed with a freshly-redrawn logo derived from its brief appearance in Chyros’s TC7063.02.A003.01 Soviet keyboard review (the logo shown in the video is depicted more precisely than on the bottoms of the switches), the museum staff were able to track down the logo to Ukrainian firm Magnit (Електромеханічний завод «Магніт») in Kaniv. Formerly part of the USSR Ministry of Radio Industry, they are now a separate business.

It is possible that they may still remember these switchces, but at present they cannot be reached as their mailbox is full!

There are still many more unidentifiable Soviet switch types, but now one of them is at least partially understood.

Sunday, 2nd February

The history of German Hall ICs is now both clearer, and less clear, after Wolfgang Zucker provided some catalogue entries for Siemens Hall ICs from 1977–1985. This in turn made it possible to locate the origin of the PDF previously used as a reference. It seems that some models were quite short-lived, being in production only during the early 1980s. This might be a clue as to why, as early as 1986, RAFI were using HFO Hall ICs. We now also have more details on SAS 201–221, albeit not the supply voltage ranges that could be tied up to RAFI’s RC 72 specifications.

Sadly, still no word from anyone at RAFI at all.


Tuesday, 28th January

In 2016, OleVoip at Deskthority posted a photograph of a lone RAFI RS 76 C switch. The Hall IC is marked only with an orange stripe (which he claimed “marks the border between the rest position and the activated position”) and the plunger is uncharacteristically natural plastic colour.

The catalogue pages for Siemens Hall ICs indicate that SAS 251 S5 is marked solely with “orange”, suggesting that this switch has a Siemens IC, and thus that the reason for the different plunger colour is that it offers dual open collector outputs instead of single open collector with enable input. There are certainly sufficient RS 76 C part numbers unaccounted for (obsolete before 2001 and removed from the catalogue) to allow for this, and we know that RC 72 offered a variety of Hall sensors.

From discussion of HFO and Siemens Hall ICs over at the Robotrontechnik-Forum, it seems certain that this is a Siemens IC, based on the plastic texture, terminal plating (silver plated instead of tinned) and housing shape (the latter remaining unexplained). However, it is always good to be as certain as possible. Wolfram Zucker in Germany has a collection of Siemens Hall ICs for sale and he has most kindly added photos of them to his analog ICs page. Most are marked in full or entirely blank (the latter indicating defective examples), but some SAS 261 chips are indeed marked with nothing but a blue stripe, and blue is the colour associated with that model.

Siemens practices remain a mystery (so far, they have declined to respond to questions) but at least it now appears certain that OleVoip’s single loose RS 76 C switch has a SAS 251 S5 Hall sensor from Siemens.

Thursday, 16th January

With the help of Holm Tiffe and the Robotrontechnik-Forum, we have made some progress understanding the Hall IC scene of the past. It seemed unlikely that VEB HFO B 461 G was around at the introduction of RAFI RS 74 C, and this was compounded by RAFI RC 72 C offering a variety of outputs (including separate level and pulse types) beyond what HFO are known to have produced.

According to the Ältester B461G? (oldest B 461 G) topic at the Robotrontechnik-Forum, B 461 G is known to go back to 1981, which corresponds with the age of TGL 38658, from June 1982. This indicates that RAFI must have been using an older product range, and this is reported to be Siemens Hall ICs. Unsurprisingly, the Siemens data matches up exactly with the RC 72 C data.

Wednesday, 15th January

At any one time, I have a considerable amount of both businesses and individuals from which I am still waiting for a response to a question or enquiry, going back days, weeks, months, or in some cases, years. Every so often, I remember or encounter some of them and give them another nudge.

The other day, I nudged RAFI again, in the hope that they might recognise the high-profile Hall effect switches found in Jacob Alexander’s Express-2 keyboard from the mid-80s. This time, I did get a reply: they are RC 72 C and RC 72 L. RC 72 is a series of high-profile Hall effect and mechanical switches. These series numbers seem to correspond with the year of introduction: RS 74 ca. 1975, and RS 76 in 1976. Tentatively these seem to be from 1973, making them slightly older than the reduced-size switches for which RAFI is better known. RC 72 is reported by RAFI to have been discontinued in 1993. Curiously, the part numbers slot in directly behind those of RS 74, which come directly before those of RS 76.

Some basic details are up; more details will come as time permits, including a complete list of part numbers. RAFI provided a single catalogue page; if they can provide further pages from it (including the extra details on RC 72), I will post those collectively, otherwise I will upload the single page available, which is just a parts list with no specifications.

Saturday, 4th January

José Soltren (XMIT) of XMIT Keyboards and now Metadot (Das Keyboard) has produced a set of photos of Das Keyboard Gamma Zulu switches (now proven to be part of Omron B3K series), revealing the part number to be B3K-T135M. The final “M” appears to indicate “Metadot” as suspected. The “35” may indicate that these have 3.5 mm travel instead of Logitech’s 3 and 3.2 mm.

This only leaves finding the part number of Creative PRES, the third customer product based on B3K.

Wednesday, 1st January

2019 knowledge round-up

2019 has been another fantastic year for keyboard knowledge, so much so that it seems unlikely that 2020 will beat it. Two major successes were Micro Switch and Fujitsu. Micro Switch has seen by far the biggest gains in knowledge, thanks to charts and literature from Honeywell Sensing and Internet of Things, National Museum of American History Library and the Computer History Museum:

Thanks to Kiyoto, the series name of every known Fujitsu discrete switch has been found:

Numerous Mechanical Enterprises types have been discovered (corresponding to unmatched patents), although most are yet to be observed:

Some other discoveries made in 2019:

Additionally, I have now a huge list of Alps patents for anyone who can read Japanese, including several for “fat Alps”.

2019 has brought with it a couple of other changes. The site graphics are now all converted to vector, to be DPI-independent (and this includes MouseFan’s site). With the exception of the switch collection, the thumbnails are all rebuilt in higher resolution (generally 150–175% DPI, as a compromise). Although my photos range from passable to execrable in quality, the increased detail level of the thumbnails does make a real difference even on a screen at only 120 DPI (125%), with the added sharpness clearly evident.

Additionally, the presence of “.php” in URLs is no longer required. The old URLs will continue to function, but they will redirect to the cleaner URLs.