deskthority

Does anyone recognize the type of switch used in this keyboard? The switch is linear. The keyboard is from a Nortel TOPS computer which is commonly used by phone companies.

$10 says they're made by Honeywell/Microswitch but it's a weird cross between SD and SC series; not entirely sure what they are.

If they are SD series I believe they're a new variant. https://telcontar.net/KBK/Micro_Switch/SD#plunger_types

I also have one, I think its pretty modern Hall Effect keyboard.

I think you are right. It likely is using Honeywell/Microswitch SD series Hall effect switches. The picture of the switch very closely resemble that of the Sun Microsystems 32-key keypad: http://mousefan.telcontar.net/image/micro.htm