Early ALPS timeline

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11 May 2021, 09:58

I have been considering the early ALPS timeline recently, namely in the design transitions from SKCC to SKCM/SKCL and in so I have developed a theory for how the switch came to be. Before we can get to that though we need to look at the predecessor: SKCC.

SKCC appears to have been introduced in either '79 or 80, and was designed (at least partially) to replace the older and more complicated spring bridge design. the slider is smaller, the spring is smaller, and the contact assembly is smaller and more easily handled as compared to spring bridge but even though the actual internals of the switch are much smaller than that of spring bridge, the switch itself has large clips to clip into the mounting plate that make it appear to be much larger than it otherwise needs to be. It appears that ALPS did not really plan beyond this either as SKCC doesn't have many variations and I do not believe it was designed for anything other than simple replacement of the spring bridge series. Take the Apple III, which can use SKCC, they don't use SKCC double action, but rather use SKFF double action. This would be because ALPS did not develop such a version of SKCC when the switch was initially introduced.

Later on someone (presumably canon) needed double action switches for their typewriters and either couldn't get SKFF anymore or didn't want to use it, and so they commissioned ALPS so make a double action version of SKCC. This switch is very similar to another prototype alps switch. Both of these switches share some common design traits that suggest alps was refining their approach to switch design as more features were being requested of their switches. The reed switches carry a lot of vestigial design elements to suggest previous developments. They look like they were intended to support dual action, latching action, and LEDs all with the same housing, only a change of internal parts would be required. ALPS was clearly attempting to future proof their design so that they could more easily develop variations of their switches for customers without needing to do extra development like SKCC double action (and I suspect SKCC latching action and LED before it) likely required.

The start of SKCL/SKCM
And this gets to prototype SKCL and the start of my theories regarding the early ALPS SKCL/SKCM timeline. These switches are clearly a prototype design, with an asymmetric slider in a board that would feature SKCM brown for the production model. I believe that another prototype board with SKCM brown switches was also sent to TI for review and TI decided to order those switches over the prototype SKCL for the board's actual production.

So with all of that background info/speculation out of the way, why do I think SKCM brown and SKCL green were both initially prototype designs, and why do I think SKCM brown was designed first? the dummy switchplate and the symmetrical top housing both seem indicative of the same sort of vestigial design characteristics as other ALPS prototypes. I feel like if alps wanted a linear switch design they would simply just leave the dummy switch plate out, or not have anything there at all and simply have a thin switch, but ALPS wasn't designing a linear switch, they were designing a double action switch that could be modified later as the client required. If SKCL had been designed first without double action in mind it would likely resemble SKCL compact and the LED would be separate from the switch entirely. The presence of SKCL LED on capslock for the TI board would indicate to me that SKCL was developed as an LED switch first and foremost, and it's use as a standard switch would have been an afterthought. SKCL green actually still has a vestigial design trait remaining in production, which is the symmetrical slider. On other switches the bottom of the slider has a rounded side facing the contact leaf, and a sharp side facing the tactile element, while SKCL green is rounded on both sides, which would imply it was designed that way to accommodate a contact leaf on both sides of the slider. This was likely not included in SKCM brown as it changes the tactility in an undesirable way (try it for yourself if you want, it isn't good) and reusing the molds for the symmetrical slider on SKCL green would make sense from a cost standpoint.

So in my proposed timeline, ALPS is attempting to develop a switch that can accommodate all the features that they think a buyer might want. Cannon is currently paying them to make a double action, so ALPS includes parts of that design in their new low proflie switch design so that they can offer double action more easily when Cannon decides they want low profile double action switches. During development they invent a method for generating tactility and so they create a tactile switch at the request of TI. TI also wants an LED switch so they remove the dummy switchplate and add an LED cutout. TI then requests a board with only the LED switch to see how they like that. Ti doesn't and so they place an order for the board with SKCM Browns. ALPS stops development on SKCM brown, they aren't a prototype anymore since they're being ordered now. ALPS continues to develop SKCL after this until it is also ordered for a full board, after which they stop developing it further since it is being actively ordered. Later another company wants tactility that isn't as extreme as SKCM brown, and so the standard single-part tactile leaf is developed. While developing this alps likely figures out how to generate an audible click. This leads into the more conventional ALPS timeline.

tl;dr: brown alps made first as a prototype then as a production switch, green alps made after that when they needed an LED switch to go with the new tactile. Green alps are then offered as a linear option for customers who don't want a tactile switch.

timeline: brown > green > cream/blue > after this point IDK

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11 May 2021, 10:03

Now, while I do think this timeline makes a lot of sense, there isn't a lot of evidence here. For instance, where is the hypothetical SKCM brown TI prototype board? What if the Prototype TI board has a normal SKCL green LED switch for caps lock? How were these decisions for a system from 1984 effecting a switch released a year earlier in 1983?

And for those I don't really have an answer. I'm not aware of any boards from 1983 with SKCM/SKCL in them, but the switches would have to be produced before TI could put them in a keyboard, and the keyboard's development wouldn't have happened all in the same year it was released so there's room for this to work just as much as there is room for other boards to predate the TI board I'm basing a lot of this off of.

If anyone has any information about SKCM/SKCL that is confirmed to predate the TI low profile boards I would love to hear about it.

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11 May 2021, 18:14

Just to add a bit more mystery to your timeline we have these unknown square profile, double spring brown Alps switches in a TI low profile board - aka 'Fat Brown' Alps for the lack of a better name.


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11 May 2021, 19:10

yeah, no idea when those fit into the timeline, but they are indicative that TI was willing to commission ALPS for switches instead of getting already available product. It is again not proof, but it kinda supports some of my reasoning.

If more was known about those in general or more of them were out in the wild then maybe more would be known about them

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