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    AST RESEARCH, INC.        TECHNICAL BULLETIN # 1097                  3-9-95

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    			 PREMMIA LX P/60 HANGS WITH PCI NETWORK CARDS

    PROBLEM

    The Racal Interlan PCI T2 board and an Adaptec 2940 rev. F board can not
    successfully share an interrupt.  When the Racal board's network software is
    invoked, the Premmia LX motherboard hangs with the following error message:

    	System Overflow
    	System Halted

    CAUSE

    The problem occurs well before the Racal board ever issues its own interrupt.
    Normal SCSI operation is "broken" once the Racal software is loaded.  A simple
    "dir" command on the SCSI drive will invoke the problem.

    The Racal software is loaded and takes over the initial handling of the
    interrupt. If the interrupt is not intended for the Racal board, a clean
    transfer to the SCSI interrupt handler should occur.  The Racal board
    determines if the interrupt is intended for the Racal board by performing
    reads to it's own register.  The Racal interrupt handler does not perform
    these reads.  The Racal interrupt also issues an "end of interrupt" command
    very early.  This "end of interrupt" command comes before the PCI interrupt
    is cleared.

    Because the PCI interrupt is level-sensitive, an additional interrupt will
    occur immediately following the "end of interrupt" command.  Additional
    interrupts follow, causing the stack overflow.

    SYSTEMS AFFECTED
    AST PART NUMBER AND DESCRIPTION

    501288-011     PREMMIA LX P60/3 8MB

    SOLUTION

    Download the software driver from Racal Interlan's BBS (508) 264-4345.
    The file name is PCODIDOS.EXE, and it is located in the ILANPCI library.