Ref: 09020008
Title: 3+SNA and Illegal OPT Code
date: 8/1/89

Copyright 3Com Corporation, 1991.  All rights reserved.

In 3+SNA version 3.0, this error message may appear on the
workstation screen:

    Illegal OPT code scheduler entered while locked

After the error appears, the workstation locks up.  The error
occurs during a session or when loading MP3274.  It indicates
that 3+SNA's multi-tasking Operating System, MPCOS, has run into
a conflict.

Following are possible causes for the message, and actions to
take to solve the problem.

1.  When configuring the gateway and workstation, the
    serialization option was left at "00".

    Action:  Change the serialization option to the NetBIOS
    interrupt "5C".

2.  NetBIOS parameters are not set correctly.

    Action:  Set the NetBIOS parameters to "NetBIOS /M /C".

3.  The NetBIOS parameters may be inadequate.

    Action:  Add to the NetBIOS parameters as follows.

         For workstation add  /D5
         For gateway add      /D7 /T7
         example: "NetBIOS /M /C /D5"

    Descriptions of the NetBIOS parameters can be found in
    several 3Com manuals, including the NetBIOS Programmers Guide
    and the NetBIOS Supplement.  Here is a brief description of
    what these parameters mean:

    The D parameter is for receive buffers on the workstation.
    The T parameter is for transmit buffers on the workstation.
    The M parameter is a multitasking switch.
    The C parameter is for displaying network retry messages.

4.  Your AUTOEXEC.BAT file contains Terminate and Stay Resident
    (TSR) programs.

    Action:  Remove TSRs from the AUTOEXEC.BAT file.

5.  The PRO.SYS parameters are set incorrectly.

    Action:  Set the PRO.SYS parameters as follows.

         8 2 2 workstation
         12 2 2 gateway
         40 2 2 PC concurrent server

6.  If nothing else solves the problem, it is possible the DOS
    concurrent session is interfering with 3+SNA.

    Action:  Turn off the DOS concurrent session through 3+SNA,
    following these steps:

        A.  Load 3+SNA.
        B.  Run CDOS OFF.
        C.  Load your word processor.
