Disc errors are errors returned by the controller. There follows a list of
the 1772 and ST506 disc error numbers.

Floppy disc (1772) error codes:

These are basically the errors returned in the status byte by the controller.

In summary here are the status bits in the status byte of a 1772:
FdcMotorOnBit   bit 7
WProtBit        bit 6  ;write protect - translated to disc write protected error
WFaultBit       bit 5  ;write fault
RnfBit          bit 4  ;record not found
CrcBit          bit 3  ;crc error
LostBit         bit 2  ;lost data
Track0Bit       bit 2
BusyBit         bit 0

So, disc error 8 is a crc error


In summary here are the error codes returned by the HD63463 (ST506) controller:

The values are the error codes shifted right by 2 bits, which give:

01      ABT     command abort has been accepted
02      IVC     invalid command
03      PER     command parameter error
04      NIN     head positioning, disc access, or drive check command before SPC has been issued
05      RTS     TST command after SPC command
06      NUS     USELD for a selected drive has not been returned
07      WFL     Write fault (WFLT) has been detected on the ST506 interface
08      NRY     Ready signal has been negated
09      NSC     Seek complete (SCP) wasn't returned before timeout
0A      ISE     SEK, or disc access command issued during a seek
0B      INC     Next cylinder address greater than number of cylinders
0C      ISR     Invalid step rate: highest-speed seek specified in normal seek mode.
0D      SKE     SEK or dis access command issued to drive with seek error
0E      OVR     data overrun (memory slower than drive)
0F      IPH     Head address greater than number of heads
10      DEE     Error Correction Code (ECC) detected an error
11      DCE     CRC error in data area
12      ECR     ECC corrected an error
13      DFE     Fatal ECC error in data area
14      NHT     In CMPD command data mismatched from host and disc
15      ICE     CRC error in ID field (not generated for ST506)
16      TOV     ID not found withing timeout
17      NIA     ID area started with an improper address mark
18      NDA     Missing address mark
19      NWR     Drive write protected


Disc errors returned by the IDE driver.
Where they can be mapped onto a similar error from the ST506 driver,
the error code is shown.

&02  IVC  command aborted by controller
&07  WFL  write fault
&08  NRY  drive not ready
&09  NSC  track 0 not found
&13  DFE  uncorrected data error
&16  TOV  sector id field not found
&17  NIA  bad block mark detected
&18  NDA  no data address mark
&20       no DRQ when expected
&21       drive busy when commanded
&22       drive busy on command completion
&23       controller did not respond within timeout
&24       unknown code in error reg


Disc errors returned by the 82C710 floppy driver.

&01       Fatal - controller hardware error
&02       Fatal - command timed out, drive problem
&03       Fatal - Track 0 not found, drive problem
&10       Critical - seek fault
&20       Non specific command error
&21       Data overrun
&22       Data CRC error
&23       Sector or ID not found
&24       Missing address mark

