Cheery Mx switches "A" marking meaning? And why some of them upside down?

[Xentios]

https://geekhack.org/index.php?topic=88594.0
I only find mention of the "A" marking here and they did not answer the question there .

So main question is in the topic . I also have an off topic question which is not important. Does the handles of the switch (+ shape part) change thickness in years? Or by colors?  I can't fit the same key caps  that fits to newer blue switches to older brown switches.

[Xentios]

Wow i never seen myself this geek that even in geek forums people can't answer my geek question.

[dr_derivative]

I went through all my loose Cherry switches to try and maybe narrow it down. There is also an A on all Cherry bottom housings, so I'm assuming they are related.

MX/M8 adapters,  Olympia Clears (based on photos online), Nixies, RGB switches, and Hiroses all have that A. So it doesn't signify the mount, dimensions, material, manufacturer of the switch. RGB switches don't have the A on the top housing since there's no room next to the RGB lens thingy, but they do have an A on the bottom housing.

I did find a pre-retool Cherry Black that had no A on the top housing, but it still had an A on the bottom.

The only switch I have without any A is a Cherry MX lock switch, so it could be something like A = Momentary (i.e. normal), no A = Alternate action. There is no other letter on the lock switch though so this seems unlikely IMO.

I guess the only people who really know is Cherry themselves.

[Xentios]

Well did you see an upside down A or normal A is mixed in a keyboard? It is maybe quality mark?

[dr_derivative]

A quick Google turned up this image of an old Wyse board.



I don't think the orientation has any meaning. The marking on Cherry housing have varied a lot over the years, just look at how much the logo varies.

I'm not sure if a quality mark would make sense since there aren't really any Cherries without the A. If all MX switches are A quality, there shouldn't be any reason to even include the A.

It could also have to do with the 'A' in MX part numbers. Most Cherry MX switches have part numbers starting in MX1A for normal or MX3A for silents. According to Cherry datasheets this A means the standard contacts, i.e. max 10mA/12V, gold plated, SPST, and normally open. It also says C is 'special', but it doesn't list meanings for any other letters. There are references to part numbers with B, C, and D online, so it is possible that these would have a different letter on those housings. These were special orders though, probably for some industrial application, so chances are we'll never see them in the keyboard world.