Almost OT: Pushbutton switch latching

[Fred Cisin]

Well, . . .
You could do it purely in mechanical hardware.  Look at an old 5 line
office phone, or an old car radio (sorry, Jay) with pushbuttons.

Or, . . .
you could do it entirely in software, using a junk PC.
Rip the tops off of all of the keys except the numerals.

NXT2: 	MOV AH,0
  	INT 16h
;	Your most recent key is in AX (ASCII in AL, scanciode in AH)
. . .
	JMP NXT2

If you want a multi-megabyte solution, you could use the "radio buttons"
in WINDOZE.


But you'd probably rather do it with relays