Commodore 128D - Page 359

APPENDIX B
DOS ERROR
MESSAGES
The following DOS error messages are returned through the DS and
DS$ variables. The DS variable contains just the error number and
the DS$ variable contains the error number, the error message, and
any corresponding track and sector number. NOTE: Error message
numbers less than 20 should be ignored with the exception of 01,
which gives information about the number of files scratched with the
SCRATCH command.
ERROR ERROR MESSAGE AND
NUMBER DESCRIPTION
20 READ ERROR (block header not found)
The disk controller is unable to locate the header of the
requested data block. Caused by an illegal sector num
ber, or the header has been destroyed.
21 READ ERROR (no sync character)
The disk controller is unable to detect a sync mark on
the desired track. Caused by misalignment of the read/
write head, no diskette is present, or unformatted or
improperly seated diskette. Can also indicate a hard
ware failure.
22 READ ERROR (data block not present)
The disk controller has been requested to read or verify
a data block that was not properly written. This error
occurs in conjunction with the BLOCK commands and
can indicate an illegal track and/or sector request.
23 READ ERROR (checksum error in data block)
This error message indicates there is an error in one or
more of the data bytes. The data has been read into the
DOS memory, but the checksum over the data is in error.
This message may also indicate hardware grounding
problems.
24 READ ERROR (byte decoding error)
The data or header has been read into the DOS memory
but a hardware error has been created due to an invalid
bit pattern in the data byte. This message may also indi
cate hardware grounding problems.
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APPENDIX B-DOS Error Messages