20 GOSUB 440: HOME : VTAB 12: PRINT "CHANGE ERROR CODES OR COMMANDS ? (E/C) ";: GET N$
30 IF N$ = "E" THEN 90
40 IF N$ < >"C" THEN 20
50 IF N$ = "C" THEN AD = 43140:B = 43272:C = 133: PRINT N$: VTAB 16: HTAB 1: INVERSE : PRINT "NO NUMBERS, PUNCTUATION MARKS OR SPACES MAY BE USED WHILE CHANGING COMMANDS"