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    AST RESEARCH, INC.         TECHNICAL BULLETIN # 1022A               4-12-95

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    		    AST EISA SYSTEMS WITH NCR SCSI HANG UNDER SCO UNIX

    PROBLEM

    AST EISA systems with an embedded NCR 53C810 PCI SCSI host adapter hang during
    boot, after installation of SCO UNIX rel. 3.2, ver. 4.2 while loading the
    file UNIX.TXT.

    CAUSE

    The on-board NCR SCSI adapter has a 1KB memory mapped resource region with a
    configurable address.  Because the EISA Configuration Utility (CU) configures
    the 1KB SCSI resource at the end of physical memory, UNIX writes to it when
    sizing memory, corrupting the SCSI adapter registers, and preventing further
    disk I/O.

    SYSTEMS AFFECTED
    AST PART NUMBER AND DESCRIPTION

    501457-XXX          PREMMIA GX/P90
    501500-XXX          MANHATTAN V-SERIES
    501502-XXX          MANHATTAN P-SERIES

    SOLUTION

    The SCSI adapter resource buffer address must be relocated before booting UNIX.

    Use the EISA CU to set the address of the 1K resource region to a value that
    is beyond the end of the system's physical memory.

    To change the resource region address through EISA CU do the following:

    	RUN         EISA-CU (version 3.02 or later)
    	SELECT      Step 3: View or Edit Details
    	SELECT      Embedded - PCI Board
    			  PCI Function 1      Enabled
    	PRESS   Edit Resources
    	SELECT      Memory Address
    	PRESS <+>   Until display reads 128M (or greater than system memory size)
    	PRESS  Save and Exit