Commodore 128 Programmer's Reference Manual page 658

648 COMMODORE 128
APPENDIX B
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DOS ERROR MESSAGES
The following DOS error messages are returned through the DS and DS$ variables, jlie [^
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: , i
Error message numbers less than 20 should be ignored with the exception of 01, which (j
gives information about the number of files scratched with the SCRATCH command.
ERROR |
NUMBER ERROR MESSAGE AND DESCRIPTION uj
20 READ ERROR (block header not found)
The disk controller is unable to locate the header of the requested data ] I
block. Causes: an illegal sector number, or the header has been destroyed. U
21 READ ERROR (no sync character) , -
The disk controller is unable to detect a sync mark on the desired track. ] j
Causes: misalignment of the read/write head, no diskette, or an unformat- ^
ted or improperly seated diskette. Can also indicate a hardware failure.
22 READ ERROR (data block not present) H
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. | j
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 ground- lj
ing problems.
24 READ ERROR (byte decoding error) j
The data or header has been read into the DOS memory but a hardware i—'
error has been created owing to an invalid bit pattern in the data byte. This
message may also indicate hardware grounding problems. \ (
25 WRITE ERROR (write-verify error) J
This message is generated if the controller detects a mismatch between the
written data and the data in the DOS memory. ) j
26 WRITE PROTECT ON u
This message is generated when the controller has been requested to write
a data block while the write protect switch is depressed. This is caused by
using a diskette with a write protect tab over the notch or a notchless diskette.
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