Commodore Amiga A500 Technical Reference Manual page 181

Sfafus and Error Bytes A t the completion of each command the HDC will return status in the
last four bytes (1 2-1 5) of the command block. The status format is
similar t o that returned by the 'Request Sense' SCSl command. This
four byte block contains error and status information pertaining t o
the last block of data transferred or a non-disk operation executed
by the HDC. The ADV bit will be set, t o indicate a valid address, if the
last operation required a disk access, otherwise ADV
=
0.
The logical unit number returned is simply the contents of the logical
unit field, where the error occurred, as defined in the drive control
block. For those commands that do not take a logical unit number as
an input parameter, the logical unit number returned in the com-
mand status byte is not meaningful.
A list of possible error codes, along with their descriptions, follows:
Error Bytes
The logical sector address bytes are t o be in the same format as that
defined in the command block. Bits 3-0 of the error byte is used for
the error codes. Bits 4 , 5 indicate the error type and 7 is the ADV bit.
Bit
6
is not used presently.
Disk Drive Error Codes (Type 0)
0 No error
1 No Index
2 Seek not complete
3 Write fault
4
Drive not ready
6 Track 0 not found
Controller Error Codes (Type 1)
11 Uncorrectable data error
1 2 Address mark not found
1 3 Sector not Found, Read
1 4 Sector not Found, Write
1 5 IDNF error
Command Error Codes (Type 2 )
2 0 lnvalid command
21 Invalid sector address
2 2 Invalid LUN
Hardware Error Codes (Type 3)
30 RAM failure (HDC)
3 1
ROM Checksum Error
3 2 Host DMA status error