The other keyboard I found in the junkpile today was a Key Tronic [sic] KB101 Plus, featuring a typical 104-key layout. I wasn't able to identify the switching mechanism, but someone noted today that Keytronic had made some capacitive boards utilizing a rubber sleeve similar to that found on the IBM M4.
This keyboard *does* have the rubber sleeve, which I can almost feel buckling as I depress the key, but at first glance it looks like it's just depressing a plunger onto a membrane. What's odd is that if I remove the keycap and just actuate the plunger with a small tool, there is clearly some sort of other spring or rubber underneath, in addition to the rubber sleeve between the keycap and the white plastic thing.
The most unusual thing about this board is probably that the lock indicator LEDs are embedded in each of the corresponding keys. As a result, there are no LEDs in the usual place, although the case is ported for them. There is simply a beige plastic sheet over the empty holes.
The connector is a 5-pin DIN. It works with an AT to PS/2 adapter regardless of whether I plug it into a PS/2 to USB adapter, or plug it into the PS/2 port on my motherboard. There is also a bank of dip switches for selecting AT or XT protocols, among some other abbreviations that I couldn't readily identify.
I think it types like crap, personally. Heavy actuation force, and little tactile feedback (n.b.: I have never typed on an M4). But what kind of switch is this?
