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    AST RESEARCH, INC.         TECHNICAL BULLETIN # 1137                4-12-95

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    				ASCENTIA 9XXN 810 MB HARD DISK DRIVE

    This is an informational bulletin.

    The 810 Megabyte hard disk drive for the Ascentia 9XXN system has demonstrated
    full compatibility with MS-DOS 6.XX, Windows 3.1X and Workgroups, and
    OS/2 2.XX/3.XX operating systems.  The drives additionally support SCO
    Unix/Open Desktop (ODT) with the exception of two areas:

    1. While performing an infinite-loop outbound large file (>1MB) transfer using
    FTP, the Unix session which controls the transfer may freeze after a period of
    approximately 2 hours.  The system may still be shut down correctly, however,
    if a file is in the FTP queue for transmission, the data may be lost if the
    file was unsaved immediately prior to entering the queue.

    The cause for this problem is in Unix itself, as it does not support drive
    geometries which have greater than 1024 cylinders.  Even if the drive is
    partitioned for 528MB (Unix maximum) the problem may still occur due to the
    translations for CHS embedded in the drive controller code.

    2. When a user has configured the hard drive for both a Unix and an MS-DOS
    partition, the FTP activities under Unix may cause some clusters in the DOS
    partition to be erroneously marked as bad, when the user changes from the
    Unix partition to the DOS partition.

    The cause for this particular problem is that Unix uses some areas of CMOS
    for in-session configuration storage, and does not remove or reset the bits
    that were changed, causing DOS to perceive bad clusters.
    The workaround for this situation is to use CHKDISK.EXE with the /F switch,
    or SCANDISK (whichever is appropriate for the version of DOS being used)
    during the DOS session to restore clusters marked as bad in error, or to mark
    genuinely bad clusters.

    SYSTEMS AFFECTED
    AST PART NUMBER AND DESCRIPTION

    All Ascentia 9XXN systems with 810 MB hard disk drives installed or with the
    option for 810 MB hard disk drives.