Power-Programmierung/CD1.mdf/lan/driver6s/romrel.doc

Text File | 1989-08-10 | 6KB | 126 lines

        Name:
    ROMREL(.COM)

Function:
    ROMREL will release the hooks into the system BIOS made by the
    Netware Remote Boot ROM to facilitate the use of alternate
    device drivers with the network interface card (NIC).

Usage:
    ROMREL <int_number>

Version:
    2.0 - Release 08/10/89

Description:
    In order to support remote booting using Netware on a PC, the
    NIC is equipped with a special ROM, usually provided by the NIC
    manufacturer.  The ROM will take control of the NIC at cold
    boot time, and map a disk image resident on the Netware server
    as drive A: on the PC.  In order to do this, the ROM must hook
    into various BIOS disk I/O vectors, as well as the card itself.
    NET3.COM contains code to, in part, undo these hooks, thereby
    returning control of the drive to the local BIOS and the NIC to
    the IPX/SPX driver.

    The purpose of ROMREL is to emulate this "unhooking" process
    normally performed by NET3 without actually loading another
    protocol in place of the ROM, as does IPX.COM.  The goal of ROMREL
    is to leave the system vectors set as if the system were loaded
    from a local hard disk or floppy without the use of the ROM.

    ROMREL is not required in the "normal" scheme of things where
    IPX and NET3 are used in the AUTOEXEC.BAT file after remote boot
    to establish a working connection to a Netware server.  ROMREL
    is required when some device driver/protocol other than IPX/SPX
    is to be loaded, or when IPX does not actually contain the NIC
    device driver.

    For example, with ROMREL the user could utilize a Netware server
    to boot DOS, but then attach to an NFS server to map a local
    drive (say, F:) to a remote filesystem.  Alternately, ROMREL
    could be used to release the ROM so a generic network driver
    can be loaded, such as a Packet Driver conforming to the FTP, Inc.
    specification.  This would allow Netware IPX/SPX to share
    the NIC with other protocols, such as TCP/IP.  Some implementations
    of the Packet Driver are incorporated into IPX.COM so as to
    eliminate the need for ROMREL.  However, most implementations
    (especially those in the Public Domain) are designed into a separate
    TSR to be loaded before IPX.COM.  Without ROMREL, this TSR would
    conflict with the Boot ROM, as both driver and ROM would be trying
    to use the NIC at the same time.

    One thing to realize at this point is that once ROMREL is executed,
    drive A: disappears.  Therefore, ROMREL would have to be used in
    conjunction with a RAM Disk so execution could continue.  To
    accomplish this, CONFIG.SYS would be configured to create a RAM
    Disk upon boot (using VDISK, for example).  The AUTOEXEC.BAT file
    would then copy from the A: image to the RAM Drive those files
    necessary for continuing execution after ROMREL.  In the previous
    example, that would include the packet driver TSR, IPX, and NET3.
    The system can then be made to log into the server and continue
    with any other initialization as necessary.

    ROMREL will release the hooks into the system DOS/BIOS and
    optionally mask off the interrupt set on board the NIC via the
    8259 bus interrupt controller.  Masking is usually done to prevent
    any spurious interrupts which may be generated by the NIC from
    jumping to the ROM interrupt handler before the new device driver
    can be loaded.  (Also, some device drivers may not properly
    install their interrupt handling code until after some internal
    initialization takes place.  During this time the NIC could
    interrupt the system and jump to the wrong device handling code.)

    If you wish to have ROMREL release the interrupt, invoke it as:

        romrel <int_number>

    where int_number is 2-7 on a PC/XT, or 2-15 on an AT.  For example,
    if the network card is set to use IRQ 2, use:

        romrel 2

    If you do not want ROMREL to release the interrupt, specify an
    int_number of 0, as:

        romrel 0

    It is highly recommended that you specify the actual IRQ number.
    Also, be careful to specify the correct interrupt number for the
    NIC.  ROMREL does not have any way of determining that the
    interrupt you specify actually belongs to the NIC.  Using the
    wrong number could, say, disable a COM port or even the floppy
    disk driver!  Be precise.

    Furthermore, ROMREL is compatible with various network-aware
    mark and release programs if invoked before a mark is issued.
    Also, if release will be used, you should have ROMREL mask off
    the card interrupt.  If you don't, the interrupt may be pointing
    back to the Boot ROM after a release is executed, and the system
    will most likely crash.

Author:
    Glen M. Marianko

Disclaimer:
    The user of this software assumes all responsibility for its
    use.  The user has been made aware of the potentially volatile
    results of incorrect use of this software, which may lead to
    the loss of data.  The user is advised to test this software
    thoroughly before relying upon it or using it in connection with
    any valuable data, and that the user frequently perform data
    backups so as to prevent any significant loss of data.
    This software is provided AS-IS without any warranty, either
    expressed or implied, as to its performance, merchantability,
    or fitness for purpose.  The entire risk as to the results
    and performance of the software is assumed by the user.
        Should the program prove to be defective, the user assumes the
    cost of all necessary servicing, correction, and repair.

Copyrights:
    Portions of ROMREL are (C) Copyright 1983, 1988 Novell, Inc.

Bugs:
    The author is not aware of any bugs as of this writing.  Please
    report any bugs directly to the author.