    AST RESEARCH, INC.         TECHNICAL BULLETIN #0689                  04-30-91

                      PREMIUM II SYSTEM BIOS AUTOSENSE FEATURE

    The Premium II BIOS (version 2.0 and above, AST part numbers 237826-001A and
    237827-001A) supports a feature known as "Autosense".  This feature allows
    the BIOS to automatically sense, and use, optimized parameters which take
    advantage of the full capacity of IDE type hard drives.

    Prior to this feature, the parameters for a particular drive had been
    determined by entering a discrete value (e.g. "17") in SETUP.  This value had
    to operate with drives from several vendors, so these parameters were not
    always optimal for a particular drive.

    This means that the same drive configured by these two methods will have two
    different sets of parameters, particularly the number of cylinders.

    Therefore, a drive which has been partitioned and formatted under a discrete
    drive type may have to be re-partitioned and re-formatted when configured by
    the autosense feature.  Make sure the following steps are taken before using
    autosense to configure a drive:

        - Save the data currently on the drive.  Save only files and directories,
          not partition information.

        - Run SETUP and choose "AUTO" for drive type.  A set of parameters will
          be returned for the installed drive.  Save the configuration and exit
          SETUP.

        - Re-partition and re-format the drive under the new configuration, and
          restore the original data.

    Note: The Conner CP-3000 40MB drive (AST part number 230092-040) cannot be
          configured via the autosense feature.  This drive must be manually
          configured as type "17" in the SETUP program.