KBK update for Friday, 1st January
2020 knowledge round-up2020 has been a strange and ultimately disappointing year for reasons unrelated to the unexpected export from the Far East of something more dangerous than cheap electrical goods.
In terms of keyboard knowledge, it seemed fairly likely that 2020 was not going to top the level of revelation of 2019, and while this seems to be true, progress has continued in spite of everything. The big breakthrough was getting catalogues from RAFI in March for their RC 72 and magnetoresistive types, the latter being to date the only known example of magnetoresistive switches. This was the first but by no means the last instance of finding details that seemed highly unlikely to be found, showing once again that so long as you keep searching, you will find.
The RAFI discoveries then led to an in-depth investigation of German Hall sensors, not least because RAFI were offering a variety of output options not covered by the HFO B 461 G sensors that we have encountered thus far. Discussion with various people in Germany and examination of various websites and catalogues has allowed me to list out both the Siemens Hall sensor ICs and the HFO Hall sensors derived from them, although the early history of the Siemens types remains poorly understood.
Several years ago, Meryl Miller offered me an assortment of switches, and I selected just the keyboard types for myself and Jacob Alexander. More accurately, I selected the ones that I believed were keyboard switches, missing the fairly obvious Micro Switch KB reed switch (which was a solder terminal type, rather than the quick connect alternative that is all I have been able to obtain to date). Less obvious was a curious contraption that turned out to be Fujitsu FES-2. The real shame was in passing up a Raytheon keyboard switch. Extensive trawling through old electronics and computing magazines at Bitsavers turned up considerably more detail on these switches than expected, giving us the identities of KBSM for the mechanical switches and KBSR and KBFR for the reed switches. (In theory, KBFM—mechanical with a flat base—should also exist, but no sign of it has been discovered to date.) Only two KBSM switches have ever been seen: the one that Meryl has since discarded, and one that had already sold on eBay, from a seller too mean to permit the now-redundant photos to be published here.
Perhaps the most surprising discovery of all, was the names of several Stackpole series names, specifically KS-200 for the high-profile arrays, KS-200E for the low-profile arrays and the interlocking discrete switches, KS-500E for low-profile membrane keyboards, and finally KS-600E for the plate-mounted discrete switches derived from KS-200E. No mention has been found to date of a KS-100.
Keyboard enthusiasts are frequently acquainted with the method by which modern keyboards operate: the switches are wired in a grid (or matrix) and scanned by firmware stored within a microcontroller, with the key definitions stored within the firmware. Far less is known about the workings of keyboards going back to the 1960s, and the many ways of implementing a keyboard before the late 1970s when it started to become cost-effective to use a microcontroller. Many of the early techniques are now covered on the encoding and output page, itself still a work in progress as more details emerge. As part of this endeavour, Micro Switch KB encoding switches are now detailed on their own page; these pre-date the reed switches by a couple of years or so, something still in line for documenting according to literature.
Other discoveries made in 2020 include:
- The Hi-Tek switches in the UB80-01AA keyboards are licence-made by Cherry in their US factory, arranged by DEC, as explained by Peter Cherry. This ties in with DEC arranging for Tontec to produce Hi-Tek array mouldings in Hong Kong, possibly with some other company producing the completed switches for those specific VT-100 keyboards.
- We have the first non-Logitech part number within Omron B3K series, from José Soltren, which has helped with understanding the part number format for B3K. Now all that remains is to obtain the switch part number from a Creative PRES switch.
- There is a possibility that the keycaps on most BBC Microcomputer keyboards are the long-lost Signature Plastics SS series.
- The internal contact arrangement of Cherry M75–M78 is now known, although it remains to be documented; specifically, the design is almost the same, but the half-width contacts are arranged in side-by-side pairs. This allows two contact pairs in an alternate action switch (with the alternate action mechanism on the rear of the plunger), or four contact pairs in a momentary switch.
- Although Oak Series 400 was already tentatively identified, the smaller type was not; these are now known to be Oak Series 475, again identified from trawling old magazines.
- Another magazine find (from scans provided by Marcin Wichary) gives us Series 555 for the “Early Ⅱ” and “Early Ⅲ” styles of Licon/Cortron ferrite core switches, leaving “Early Ⅰ” to be the original Series 550. Confusingly, we now know that a Series III existed, but from the description, this is not the tall switches in 35-* keyboard models. Just as confusingly, the DIN-compliant switches seemed to be split between two separate series: FC-2550 and FC2500 (with only the former having a hyphen). Details on both series remains too vague to understand how they differed, but the suggestion seems to be that FC-2550 had model numbers beginning 25-5* while FC2500 had model numbers beginning 25-0*, something that cannot be proven one way or the other due to how few examples have been properly documented by their owners.
- The confusion around Micro Switch CT and its relationship with ST is now explained: the original two series were capacitive membrane SC and contact membrane CT. ST silent tactile keyboards superseded both, replacing the click spring with a rubber dome, and providing both membrane types under a single series.
- Electronic Engineers Master from 1989–1990 provides a list of features and part numbers for Marquardt Series 6184, indicating that the series included alternate action, tactile feedback and a choice of 2.5 mm and 4 mm travel. Later, a click-tactile type would show up in California, which for now is being presumed to be the tactile type (something Marquardt have neither confirmed nor denied). The click mechanism is something not seen before, and is illustrated on the Series 6184 page.
- Several more MEI T-5 Series subseries are now known, from old advertisements.
- Maxi-Switch “vintage linear” may be 6000 Series, although this remains to be formally confirmed. These switches are now almost certainly made by SMK or made using tooling licensed from SMK, which explains why the “integrated dome” type bears a very strong resemblance to another SMK series.
- It now seems likely that the Fujitsu “sheet keyboard” system is FES-3001 while the “typewriter” form (the full travel type) is FES-301. Following the introduction of DIN ergonomic standards, a lower-profile version of FES-301 was adopted, which is FES-301E (Fujitsu provided this series name and indicated that “E” denotes “ergonomic”).
- Another magazine find was a brief advertisement for SMK JM-0400 series. J-M0404 and the heretofore unobserved J-M0409 fall within this overall series. Most interestingly, JM-0400 included reed switches. We already knew that SMK produced reed switches, but not that they miniaturised them. It seems that SMK filed few patents, or they are still awaiting digital recording, as very little showed up on J-PlatPat for SMK, with no reed or integrated dome types appearing at all.
- Just as understanding of Alps was starting to improve, 2020 has dealt it some blows. Jacob Alexander has found a new Alps reed type, this time classified as SCF instead of SCB. This would suggest that even in the S-code era, each series had its own identity, but that does nothing to clear up the confusion around CH and SCH. An old advertisement for Alps switches and keypads gives a totally different series identity, in a way that does not make sense, but with the spring bridge switches considered to fall under SCH being listed as AKC.
- The origin of Cherry MY is now much better understood. The different types remain a mystery; even Günter Murmann was unable to recall anything about them.
- There is now clear evidence that HP bought “mousetrap” switches from Cherry; more details are given on the new Cherry Series S31 page.
All things considered, 2020 has fared significantly better than it could have, and with luck 2021 will be at least as bountiful.
View within the updates for 2021
Comments
None yet.