Drive Functions - Zenith Z-100 Reference Manual

Page 9.12
Disk Drives
Error Status Codes
All of the drive function calls will return a status code in register AH upon comple-
tion. AH will either contain 0 if the carry flag is not set, or a value representing
a specific error if the carry flag is set. Table 9.9 defines the error codes.
Table 9.9. Drive Error Codes
C ODE ERR O R
01 Bad command.
Illegal command was given to I/O routine.
02 Bad address mark.
The controller did not find an address mark.
Write protect.
04
A write or format operation was attempted but disk was write protected.
Winchester controller reset failed.
05
Controller did not accept drive parameters.
07
08 DMA overflow.
DMA controller could not keep up with disk data and information was
lost.
Usually results from excessive DMA access from other devices on the da,
bus or a bus interface hardware failure.
09 DMA boundary error.
Hardware is incapable of transferring sector information across 64K bound-
aries. Can be corrected by reducing sector count in AL or by changing
buffer pointer so that entire transfer area can reside within a single segment.
10 Bad CRC on diskette.
Specified record was found, but CRC for the data did not match what was
calculated by the controller. On Winchester drives, flags that an error oc-
curred which could not be rectified by the ECC circuitry.
Winchester drives only.
Indicates that an ECC error occurred but controller was unable to reconstruct
lost data.
20 Disk controller card is defective.
40 Bad seek
Controller attempted to move read/write head to specified track, but could
not find sector header on that track which matched the correct track number.
Time-out error.
80
Occurs when a command has been issued to the controller, but is n«
completed within a reasonable amount of time.
BB Undefined error, usually bad controller.
FF Winchester only.
Indicates that a sense drive status operation failed.