STRING A
OPENCONSOLE
PRINT "Press Q to quit"
DO
   A = INKEY$
   SELECT A
      CASE "A"
         MySubA()
      CASE "B"
         MySubB()
      CASE "C"
         MySubC()
   ENDSELECT
UNTIL A = "Q"
CLOSECONSOLE
END

SUB MySubA()
	? "A"
	RETURN
ENDSUB

SUB MySubB()
	? "B"
	RETURN
ENDSUB

SUB MySubC()
	? "C"
	RETURN
ENDSUB