AT&T 6300 Service Manual page 223

DIAGNOSTICS
If you press the 1 key followed by the ENTER key, the following
is displayed:
INSERT DISKETTE DRIVE B:
PRESS 'ENTER' KEY TO CONTINUE ­
After you press the ENTER key, the following will appear:
FORMATTING .... FORMAT COMPLETE
PRESS 'ENTER' KEY TO CONTINUE ­
4-31