deskthority

I found this for 5 EUR (and later found another one nib), the picture on the auction page was very bad but it looked old. To my surprise it came New In Box and has a built in calculator/clock.

Made by Syncan/Can Technology/Cheng Ya:
http://www.can-tech.com.tw/html/history.html

Moreover, I haven't seen this type of Cheng Ya buckling spring before.
I think they are the only other company that made buckling springs.

The other type that I've seen can be found here, it isn't rated very well:
http://park16.wakwak.com/~ex4/kb/main_n ... _touch.htm
http://geekhack.org/showwiki.php?title=Island:4721
http://geekhack.org/showthread.php?t=5341

However it is slightly different - different spring, slightly different hammer shape and transparent instead of opaque. On the back is the patent number as mentioned by chloe on geekhack for the Cheng Ya as issued in 1993. However, the FCC ID on my keyboard was granted in 1991. Still not as good as the IBM buckling spring, but smooth, clicky action and it works. Feels a bit cheap.

The calculator and clock work, but the LCD display is funky and not working well. When I disconnected the keyboard and put it in the box, the clock went on running for half a minute. I still have to try the other one I found later.

speak sound and key lock!.... what?

You can lock the keyboard. And you can play click sounds.

Lock keyboards like a boss.

I wish the Model M had removable buckling spring units. Still need to make me a Ripster-style "chopstick-of-death"

You mean sandy55 style?

Touché