Commodore 1541 - Drive Not Ready

73: DOS MISMATCH (73, CBM DOS V2.6 1541)
DOS 1 and 2 are read compatible but not write compatible. Disks may be inter
changeably read with either DOS, but a disk formatted on one version cannot be
written upon with the other version because the format is different. This error is
displayed whenever an attempt is made io write upon a disk which has been for
matted in a non-compatible format. {A utility routine is available to assist in
converting from one formal to another.) This message may also appear after
power up.
74: DRIVE NOT READY
An attempt has been made to access ihe 1541 Single Drive Floppy Disk without
any diskettes present in either drive.
56