TITLE
    Macintosh Internal Hard Drive: Problems When Using Other Drives
Article ID:
Created:
Modified: 		2221
4/2/87
8/7/92
TOPIC



    When I hook up an external SCSI hard drive to my Macintosh SE, the
    internal drive crashes at bootup. What's going on?

DISCUSSION

    When used with other external SCSI drives, a Macintosh SE or Macintosh II
    equipped with an internal SCSI drive may develop compatibility problems,
    such as the inability to boot up without crashing. This happens because:

    - The Macintosh internal SCSI drive and the external hard drive have the
    same SCSI priority number.

    - The external drive contains an older driver that will not work with the
    newer Macintoshes.

    The first problem pertains only to those external SCSI drives that have
    the SCSI priority number set to 0 in their firmware, such as the AST 4000.
    Although AST drives are presently jumpered to have a priority number of 0,
    AST is replacing the jumper block on the 4000 with a dip switch, which
    will make changing the priority easier. The priority numbers in other AST
    and external Rodime drives are either set to a number other than 0 or can
    be changed easily. A customer who needs to change the priority number of a
    AST 4000 should contact AST for complete directions.

    The workaround to the second problem is simply to update or reinitialize
    the driver using the Apple HD SC Setup.



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