10 REM STRING LOGICAL 'NOT' TEST PROGRAM
20 PRINT "TYPE A YES OR A NOT";
30 INPUT A$
40 IF NOT(A$="YES" OR A$="NO") THEN 70
50 PRINT "THANK YOU"
60 GOTO 99
70 PRINT A$;" IS NEITHER YES NOR NO!"
80 GOTO 20
99 END
