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    AST RESEARCH, INC.          TECHNICAL BULLETIN # 1467               3-21-96

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    		  Manhattan P5133 Reboots and Hangs at POST 38

    PROBLEM

    1. Windows NT may hang at POST 38h or "Hardware Malfunction Error".
    2. Netware may "Abend with NMI Error." (Manhattan P5133 only).

    CAUSE

    "Ground Bounce" occurs within the second level cache.

    ADDITIONAL INFORMATION

    During Cache Reads from the CPU, "Ground Bouncing" may occur in the
    second level cache if the internal data bus transitions from low to high, on
    multiple data lines, within the same cycle.  This "Ground Bounce" can result
    in a "glitch" on the CPU data bus, during a critical sampling period, which
    results in incorrect data sampled by the CPU.
    The incorrect data results in a parity error when the CPU performs a parity
    check.  The CPU responds by asserting a Non Maskable Interrupt (NMI)
    which is intercepted by the Operating System.  Windows NT responds to the
    NMI in one of two ways

    1.) NT will reboot and hang at POST 38h.
    2.) NT will hang with a "Hardware Malfunction Error" on the screen.

    The type of error reported by Windows NT depends on the setting of the
    "System Recovery" options in Control Panel.  Netware will respond to the
    NMI with an "Abend: NMI Parity Error".

    NOTE: This failure only occurs on the 133Mhz CPU due to it's stringent
    noise rejection characteristics.  See 1398TB.TXT for other causes of POST
    38h or "Hardware Malfunction Error" under NT.

    SOLUTION

    Install the AST CPU Termination Module.

    ADDITIONAL INFORMATION

    AST has designed a CPU Termination Module that will slow down the rise
    time on the data bus.  This change in rise time helps attenuate the amount of
    current required by the cache to drive the data bus and therefore minimizes
    the "Ground Bouncing" effect.

    SYSTEMS AFFECTED

    All 133Mhz Manhattan P Servers built prior to March, 18 1996.

    AST Part Number and Description

    501830-XXX               Manhattan P/5133 All Models

    PARTS REQUIRED
    AST Part Number and Description

    590014-001      AST CPU Termination Module
    501617-004      AST CPU Termination Module with CPU Installed

    To request a Termination Module, contact AST Technical Support at
    1-800-727-1278, or at any international AST Authorized Reseller.  Request

    AST Part Number 590014-001 (Termination Module)
    or
    AST Part Number 501617-004 (Termination Module w/CPU).

    PROCEDURE

    For single CPU systems, install the AST CPU Termination Module
    (AST P/N 590014-001) in the secondary CPU ZIF Socket.

    For systems with dual CPUs, remove the secondary CPU and install the
    AST CPU Termination Module with a pre-installed CPU
    (AST option kit 501617-004). This kit will contain an Intel Pentium 133MHz
    CPU with the termination module already installed.
    Return the old CPU to AST.

    NOTE

    Do not attempt to manually install a CPU directly into the termination
    module.  The force required to properly install the CPU manually will break
    the CPU chip and/or bend its pins.

    DISCLAIMER

    AST can not be held liable for any damage to any CPU inserted into the
    Termination Module, including damage to the processor chip, CPU socket, or
    Termination Module.

    ADDITIONAL INFORMATION

    Systems built after March 18, 1996 are not affected by this problem.
    The Termination Module will be installed in the second CPU socket at the
    time of manufacture.  The date of manufacture can be determined by
    inspecting the serial number for the following properties:

    Complete Serial  Number:  WWYLPP123456

    WWY    = Week and Year of manufacture
    L      = Manufacturing Location
    PP     = Product Code
    123456 = Sequential numbering

    To identify systems built after March, 18 1996, the first three digits will
    be 126, indicating the twelfth week of 1996.

    Systems shipped from the factory with the Termination Module installed,
    may also be identified by visually inspecting the second processor socket on
    the CPU board.  The socket will have a small module installed, with a sticker
    covering the CPU chip installation holes.  This sticker will read,

          "To install a second microprocessor, remove this adapter and insert
           AST part number 501617-004."

    Pentium is a registered trademark of Intel Corporation.