10 REM FILE TEST
20 OPEN 1, 8, 4, "TESTFILE,SEQ,W"
30 IF ST <> 0 THEN PRINT "FILE ERROR"
40 IF ST = 0 THEN PRINT "FILE EXISTS"
50 CLOSE 1

ILLEGAL DEVICE NUMBER

ERROR: #EL5MFY9Q7E0QYDN1N87WZO3Z19XL58CO