User`s manual

DESCRIPTIONOF DOS ERROR MESSAGES
NOTE: Error message numbers less than 20 ~hould be ignored with the
exception of 01 which gives information about the number of files scratched
with the SCRATCHcommand.
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 number, 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 hardware
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 message occurs in conjunction with
the BLOCKcommands and indicates an illegaltrack and/or sector request.
23: READ ERROR (checksum error in data block)
This error message indicates that 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
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
messagemay also indicate grounding problems.
25: WRITE ERROR (write-verify error)
This message is generated if the controller detects a mismatch between the
written data and the data in the DOS memory.
26: WRITE PROTECT ON
This message is generated when the controller has been requested to write
a data block while the write protect switch is depressed. Typically, this is
caused by using a diskette with a write protect tab over the notch.
27: READ ERROR (checksum error in header)
The controller has detected an error in the header of the requested data
block. The block has not been read into the DOS memory. This message
may also indicate grounding problems.
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