deskthority

This is the keyboard from a 1974 HAL DKB-2010 RTTY console. When I first looked at it, I thought it was a variant of the Hi-Tek/Stackpole modular linear switches. When I removed the top, I had quite a surprise. The switch "contacts" are two concentric coil springs. I am not certain when or how they come in contact to complete the circuit. I believe the horizontal wire at the top of the outer sprint contacts the top of the inner spring.
It uses a dedicated keyboard controller IC; the well known (at that time) National Semiconductor MM57040




The 3341 white and gold ICs are 64x4 serial memory for an onboard keybuffer.

Ha I saw the pics you were uploading to the wiki a while ago and thought...WTF is that? Very interesting find, I've never seen one like it. So do you have the other keycaps?

seebart wrote: Ha I saw the pics you were uploading to the wiki a while ago and thought...WTF is that? Very interesting find, I've never seen one like it. So do you have the other keycaps?

Yes...I need to take some photos of the housing, etc I will add keycap photos along with them. I want to get the switch photos up and see if someone is familiar with them.

Getting closer to something older than me but still short a few years

Those springs are really something.

My tendons are screaming... Do they feel heavy?

They are moderately heavy, but not too bad. While the spring has few turns and the wire is slightly thicker, the large diameter keeps the spring rate down.

You should bring this out sometime. I'd love to see this in person. Excellent shots as well.

my bamboo table = your shag rug

I know that the switches probably weren't made by National Semiconductor, but I can't help but wonder how confused people would get if they read:

"National Semiconductor Spring Over Spring switch."

Wat? Spring ovr spring? U cant b serious, m8.

How about: "National Semiconductor double Spring switch" ?

It came out of a HAL Communications device, so I would go for HAL over NS. If we are being silly, how about "slider over spring over spring" SOSOS (sō-sôs)
Just plain SOS works too. It was from a device that generates morse code after all · · · – – – · · ·