deskthority

I always thought there was only one variant of BTC dome with sliders. Apparently I was wrong

I've noticed that many of the newer BTC keyboards use these rectangular sliders on the stabilized keys, likely to simplify the chassis construction and cut manufacturing costs.
I've only ever seen these sliders on BTC keyboards. The earliest example is from 1999, whereas the newest example is as new as 2005.
I wasn't entirely sure that these were from BTC until I opened up the keyboard, where I found BTC printed on both the top and bottom casing. The example also had a very BTC-like FCC ID, starting with E5X. One of them even has the iconic 1.25u Esc key that BTC is fairly well-known for.
I also found these blue sliders in a much older BTC eKB-5190, which appear to be significantly longer than the newer black sliders:
As for the keycap mount, it looks as if it might support Alps keycaps, but unfortunately it won't. It's a different size altogether, and the slider is rotated 90 degrees, so even if it did support Alps caps, you'd have quite a hard time typing on sideways keycaps. Unless that's your kind of thing, of course.
Overall, this is something quite new to me. Are there any examples of these switches being used in an entire keyboard? Is BTC the only manufacturer that is known to use these switches?

That's just the stabiliser, isn't it?

Not really, the key otherwise doesn't work without the slider in place, and there is already a stabilizer bar present on the first picture.

It looks like a stabilizer insert to me as well. Isn't that left shift key in your first photo actuated by the dome to the right of the slider?

This stabilizer setup looks pretty reminiscent of the one the Model F AT BAE used.

Nope, that other dome acts as the > or \ key that you'd see next to the left shift key on an ISO layout. It's actually the opposite; the slider integrated into the keycap (not the rectangular Alps-like peg) acts to stabilize the keycap and does not register a keypress without the black slider. It looks like it might be able to press down on the dome, but it can't.

keycap wrote: ↑I've noticed that many of the newer BTC keyboards use these rectangular sliders on the stabilized keys, likely to simplify the chassis construction and cut manufacturing costs.

That's something that needs some pictures to fully illustrate.

keycap wrote: ↑Overall, this is something quite new to me. Are there any examples of these switches being used in an entire keyboard? Is BTC the only manufacturer that is known to use these switches?

Rubber domes don't get a lot of scrutiny, strangely enough! What makes them more frustrating is that all too often there are no identifying marks from the manufacturer. For example, I had a Viglen KU-something that I identified as Chicony from the characteristics of the PCB numbers, but nowhere does Chicony's name appear. It also has Chicony-shaped keycaps. A very similar keyboard was made by Cherry, and on inspection, that too was clearly a Chicony, something that Cherry confirmed.

http://utensilia.tk/maxdata-cherry_kb-0556/

The funny thing is that it's branded MaxData, and made for MaxData by Cherry, and made for Cherry by Chicony!


I started drawing diagrams of the different keycap shapes (the "slider" part of it, whatever you'd call that, together with the OEMs:

http://telcontar.net/KBK/RubberdOEMs/

It turns out to be far, far more awkward in 96 DPI to get the dimensions right. It's also very hard to measure, and the parts are too small and too awkwardly-shaped to draw them on instinct.

I don't have the photography setup and skills to take decent pictures (not with black keycaps), as that would be so much easier. (All the keyboards I have access to, that I've stolen keycaps from, are black.) Having a nice page of keycap photos on the wiki for rubber dome OEM identification would be nice, as it's always nice to know just where a keyboard actually came from.

With your BTC keyboard, they did at least brand it, which is nice!

Indeed, branding can be very confusing. A lot of Chicony boards use the KB-xxxx model number, but I have seen a few non-Chicony keyboards use that naming scheme, too. At least the Silitek/NMB keyboards are relatively easy to spot out.

I have seen quite a lot of these keyboards with the sliders on the stabilized keys, never felt like picking them up because I wasn't aware that they even had domes with sliders in them. I'm sure a lot of people have dismissed these and never got a chance to see the sliders because they are only under the stabilized keycaps, and nobody wants to waste their time trying to reseat the stabilizer bar.

I'm going to look out for more of these. It's very possible that (at one point) they had a large excess of these sliders and produced a few keyboards full of them.

I do have a few niggling mysteries, in particular, did the original RT-101 membrane keyboard have sliders (one assumes so, but it's not proven), and when RT-101 was split up as part of the new numbering scheme, what series was used for the membrane keyboards? The Series 725 keyboards became RT-8nnn, but I don't know what the membrane version started out as before additional membrane series were created (such as the membrane SGI granite keyboard).

Something on my to-do list is to find out more about the history of membrane keyboards. Datanetics elastic diaphragm array (that I wrote about here a week or two back, that seemed to go over everyone's heads completely) is a 1968/69 membrane system. The chief inventor at Datanetics, Mike Muller, has disappeared; I don't know how old he is (Meryl's over 80) and he could easily be 70 if he's still alive!

Big name membrane brands go back to the mid to late 80s. IBM of course. D'Milo Hallerberg mentioned to me over the phone that he thought that Hi-Tek had their new membrane system under development when NMB bought them around 1983/84; I don't know how old RT-101 membrane actually is, and whether it's ever been seen in Model F layout or not.

The gap period is around 1970–1985. Mitsumi made cheap keyboards but they weren't membrane yet.

PS your Alps integrated dome switches wouldn't suffer from being cropped, as cropped images fill more of the gallery thumbnails.

Daniel Beardsmore wrote: ↑ PS your Alps integrated dome switches wouldn't suffer from being cropped, as cropped images fill more of the gallery thumbnails.

I was actually planning on doing that today I'm also going to add some internal pics of the BTC 5100C and disassembly photos for BTC dome with sliders.