
             QEMM and XtraDrive Disk Compression Software

 Quarterdeck Technical Note #199             Filename: XTRADRV.TEC
 by Robert Gaustad                         CompuServe: XTRADR.ZIP
 Last revised: June 10, 1993                 Category: SW3

 Subject: Frequently asked questions about QEMM and XtraDrive.

             QEMM and XtraDrive Disk Compression Software

 XtraDrive is a disk compression program published by Integrated
 Information Technology.  While this program is generally
 compatible with QEMM, some issues must be addressed.  Below are
 some of the most frequently asked questions about XtraDrive and
 QEMM.

 STEALTH ROM:

 Q. When I try to install XtraDrive on a system that has QEMM and
    Stealth ROM running, I get the following error message:

    "Drive 1 is being controlled by a program that appropriates
    INT13.  You cannot install XtraDrive on this drive."

    What do I have to do to fix this?

 A. Remove the Stealth ROM parameter (ST:M or ST:F) from the QEMM
    device line and try to install XtraDrive again.  You should
    only need to do this during the installation of XtraDrive.
    Once XtraDrive is installed, you can restore the Stealth ROM
    parameter.

 Q. So, I can use XtraDrive with QEMM's Stealth ROM parameter?

 A. Under most circumstances, Stealth ROM works fine with
    XtraDrive, but if you are using the XtraDrive EMS cache you
    cannot use either of QEMM's Stealth ROM parameter (ST:M or
    ST:F). The XtraDrive EMS cache accesses the disk via the page
    frame and this causes a conflict with Stealth ROM. Normally, if
    a program accesses the disk via the page frame, QEMM's DBF=2
    parameter will fix the problem.  This is not possible with
    XtraDrive.  The EMS cache will also cause problems with drivers
    such as EMSNETX.COM and Microsoft's MOUSE.COM using EMS.

 Q. Are there any other possible conflicts with XtraDrive and
    QEMM's Stealth ROM parameter?

 A. Under certain rare circumstances you may need to exclude a 4K
    region in the system ROM BIOS area.  If, after installing
    XtraDrive and QEMM with the Stealth ROM parameter, you get an
    Exception 13 or lockup you should refer to Technical Bulletin
    #205, STEALTH.TEC.  This technote will help you determine which
    area must be excluded. Keep in mind, however, that the need to
    exclude the 4k block of High RAM is very rare.   (If you are
    using QEMM 7.0, STEALTH.TEC was placed in your QEMM\TECHNOTE
    directory during installation. If you have an earlier version
    of QEMM, you can obtain this technote through our standard
    support channels.)

 EXCLUDES:

 Q. When I install QEMM on a system that has XtraDrive currently
    installed, I get a lockup or Exception 13 when I reboot the
    machine, loading QEMM. What do I have to do to allow me to boot
    the system?

 A. Simply reboot the machine and when it beeps after checking the
    memory, hold down the ALT key until prompted to press ESC to
    unload QEMM.  (If you are using QEMM 7.0's DOS-UP, you will
    first be prompted to press ESC to unload DOSDATA.)  Once you
    have unloaded DOSDATA and/or QEMM, load your CONFIG.SYS file
    into a text editor. If you have MS-DOS 5 or MS-DOS 6, you may
    load the DOS Editor, by typing EDIT C:\CONFIG.SYS and <ENTER>.
    At the end of the QEMM device line, place the following
    parameter:

    X=9000-9FFF.

    A sample QEMM device line would then read as follows:

    DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=9000-9FFF

    After adding the parameter, simply save the CONFIG.SYS file and
    reboot your machine.

 Q. When I installed XtraDrive after QEMM, XtraDrive placed an exclusion
    from 8000-A000 on the QEMM device line.  Do I need this exclusion and
    will it take away any memory from my system?

 A. Given the way that XtraDrive is currently designed, an
    exclusion is needed.  If you are using DESQview or DESQview/X,
    the exclusion will tell QEMM to not map memory into that area,
    so the amount of memory available to each DESQview window will
    be smaller. There are a couple of things you can do to increase
    your window size if you are using DESQview or DESQview/X:

 1. The default exclude is 8000-A000, a 128K block.  Our testing
    has determined that usually an exclusion of 9000-9FFF will be
    sufficient. This will decrease your window size by only 64K.
    If you are using the CONVENTIONAL MEMORY disk cache, and have
    selected more than two 16K blocks of conventional memory, you
    will need to change the exclude back to 8000-9FFF.

                                OR

 2. Load the XtraDrive driver BEFORE QEMM and take the exclude off
    the QEMM device line.  This should decrease your window size by
    only about 46K. Once again, if you are using the CONVENTIONAL
    MEMORY disk cache, your driver size will increase with each 16K
    block you add.  The default is one 16K block. If you select two
    blocks, your driver will be 66K.  If you select three it will
    be 82K.  The maximum, four 16K blocks will result in a 98K
    driver.  Your DESQview and DESQview/X window sizes will
    decrease accordingly.


  BUS-MASTERING:

 Q. If I have a SCSI bus-mastering controller, can I load the
    XtraDrive device driver into High Ram?

 A. No.  Even with double buffering, on a system with a SCSI
    bus-mastering device you will not be able to load XtraDrive
    into High Ram.  This is NOT a memory manager issue, but a
    limitation of XtraDrive.

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 *      Trademarks are property of their respective owners.       *
 *   This and other technical notes may be available in updated   *
 *     forms through Quarterdeck's standard support channels.     *
 *          Copyright (C) 1996 Quarterdeck Corporation            *
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