Commodore 1551 User Manual page 84

65: NOBLOCK
Occurs in conjunction with B-A. The sector you tried to allocate is already
allocated. The track and sector numbers returned are the next higher track and
sector available. If the track number returned is zero (0), all remaining sectors are
full. If the diskette is not full yet, try a lower track and sector.
66: ILLEGAL TRACK AND SECTOR
The DOS has attempted to access a track or sector which does not exist. May
indicate a faulty link pointer in a data block.
67: ILLEGAL SYSTEM TOR S
This special error message indicates an illegal system track or block.
70: NO CHANNEL (available)
The requested channel is not available, or all channels are in use. A maximum of
three sequential files or one relative file plus one sequential file may be opened at
one time, plus the command channel. Do not omit the drive number in a sequential
Open command, or only two sequential files can be used. Close all files as soon as
you no longer need them.
71: DIRECTORY ERROR
The BAM (Block Availability Map) on the diskette does not match the copy in disk
memory. To correct. Initialize the diskette.
72: DISK FULL
Either the diskette or its directory is full. DISK FULL is sent when 2 blocks are still
available, allowing the current file to be closed. If you get this message and the
directory shows any blocks left, you have too many separate files in your directory,
and will need to combine some, delete any that are no longer needed, or copy some
to another diskette.
73: DOS MISMATCH (CBM DOS V2.6 TDISK" .0)
If the disk error status is checked when the drive is first turned on, before a
directory or other command has been given, this message will appear. In that use, it
is not an error, but rather an easy way to see which version of DOS is in use. If the
message appears at other times, an attempt has been made to write to a diskette with
an incompatible format, such as the former DOS I on the Commodore 2040 disk
drive. Use one of the copy programs on the Test/Demo diskette to copy the desired
file(s) to a 1551 diskette.
74: DRIVE NOT READY
An attempt has been made to access the 1551 single disk without a formatted
diskette in place. Blank diskettes cannot be used until they have been formatted.
76