> Looking for advice on a way to insure that only one of four push
> buttons is active at one time

Rick, how about something like this, if ANDed pins are in temp <3:0>

         movlw   .1
         xorwf   temp,w
         bz      key1
         xorlw   .1^.2
         bz      key2
         xorlw   .2^.4
         bz      key3
         xorlw   .4^.8
         bz      key4

;multiple key trap here

key1 ;only key 1, temp = 00000001
key2 ;only key 2, temp = 00000010
key3 ;only key 3, temp = 00000100
key4 ;only key 4, temp = 00001000

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