AH (Hex) Definition11 ECC Corrected Data Error: Returned SCSI ASC:17h - Recovered Read Error without ECC18h - Recovered Read Error with ECC20 General Controller Failure: Returned SCSI ASC:01h 03h 05h 06h 07h 08h 09h 1Bh 1Ch 1Dh 40h 41h 42h 43h 44h 46h47h 48h 49h40 Seek Operation Failed: Returned SCSI ASC:15h - Seek Positioning Error02h - No Seek Complete80 Time-out: Host adapter not responding to BIOSAA Device Not Ready: Returned SCSI ASC:04h - LUN not ready28h - Unit Attention, Ready29h - Unit Attention, Power on2Ah - Unit Attention, Mode Select ChangeBB Undefined error occurred: A SCSI ASC other than those listed wasreturned by the target.CC Write Fault: Not returned by AHA-1740A/1742A BIOSFF Sense Operation Failed: An error occurred issuing the SCSI requestsense command to the target.Hardware BIOS Commands(AH) = 00h - Reset Disk SystemThis function does nothing to SCSI drives. Regardless of drive number, this requestis passed to the original Int 13h vector so that floppy and non-SCSI drives may bereset.(AH) = 01h - Read Status of Last OperationThe status of the last operation performed is returned. The status is reset to zero.(AH) = 02h - Read Desired Sectors into MemoryThe sectors requested are read from the disk to system memory. A Read (Extended)command (SCSI Operation Code 28h) is used to execute this function.(AH) = 03h - Write Desired Sectors from MemoryThe sectors requested are written from system memory to the disk. A Write (Ex-tended) command (SCSI Operation Code 2Ah) is used to execute this function.(AH) = 04h - Verify Desired SectorsThe sectors requested are verified to be correctly written on the SCSI disk. A Verifycommand (SCSI Operation Code 2Fh) with the byte check bit set to zero is used toexecute this function. If the verify function is not supported by the selected disk, aRead (Extended) command is used and the data is thrown away.(AH) = 06 - Identify SCSI DevicesThis is a special call that is used to return the first supported SCSI drive. If there areonly SCSI drives, then the return value will be 80h. If there is a SCSI and a standardcontroller, then the return value will be 81h.EISA-to-Fast SCSI Host Adapter Onboard BIOS Interface7-7
