    AST Research, Inc.      Technical Bulletin # 1296               8/21/95

                        Bravo MS P/90 Video Shadow Effect

    PROBLEM:

    The Bravo MS P/90 system may have a strong video "shadow effect".

    CAUSE:

    The problem is caused by noise sensitivity of the feature connector from
    the Cirrus Logic 543x video chipset.

    SYSTEMS AFFECTED:

    501651-XXX                    Bravo MS P/90
    501533-XXX                    Bravo MS P/60

    SOLUTION:

    There different solutions for each independent OS video driver.

    DOS/Windows

    1.  Download the file P-BUS.EXE from AST On-Line! BBS.

    2.  Copy the file into a temporary directory. Once copied type P-BUS for the
        file to self-extract.

    3.  At the DOS prompt type 5434_DOS to disable or enable the feature connector.

         For those user who need to use the feature connector, do not
         run this program.

    WINDOWS NT

    1.  Download the file P-BUS.EXE from AST On-Line! BBS.

    2.  Copy the file into a temporary directory on the hard drive. Once copied
        type P-BUS for the file to self-extract. Copy the files to a blank diskette.

    3.  Run the program 5434_NT to disable or enable the
        feature connector with diskette in drive A:.

    OS/2 (3.0) WARP

    1. Please refer to the video installation section on the OS/2 Drivers Installation
        Manual.

        Use Setup.cmd to install the Corrective Service Pack and then use OS/2's
        Display drivers install to install the new version of the display drivers.

        After installation is complete modify SVGADATA.PMI
        by adding two additional statements on the first [LOCK] field.

    [LOCK]

    outb(0x3c4,0x18);
    outb(0x3c5,0xc0);

         This modification in the SVGADATA.PMI will turn off the feature
         connector. If the feature connector is needed, do not modify the
         SVGADATA.PMI file.

    CAUTION

    This modification should be performed ONLY by a qualified service technician.
    It is strongly recommended that this change be completed by an AST Authorized
    Service Center.  In no case will AST Research, Inc. be liable for damage to
    the system and its components, or loss of data caused by improper modification.

    PREREQUISITES

    A full backup of all data on the hard drive in the computer is strongly suggested.

    TIME REQUIRED

    30 minutes.

    CHECK-OUT PROCEDURE

    To verify shadow effect has been eliminated.