When the device driver returns control to the calling program after initiating (and completing in most cases) the prescribed function, a function call return code is returned in the AX register. These codes are shown in Table 1.
| AX Register Contents | Description |
|---|---|
| 00 | Function call accepted. |
| 01 | Function call unknown. |
| 02 | A device with this SCSI ID is not available. |
| 03 | Invalid data pointer. |
| 04 | Previous function call for this drive not yet complete. |
| 05 | Previous data transfer for any drive not yet complete. |
| 06 | Unknown error. |
| 07 | Device driver internal error. |
| 08 | Device time out. |
| 09 | Device driver busy. |
| 0A | DMA boundary crossing. |