Category : Alternate Operating Systems - Quarterdeck DesqView, CP/M, etc
Archive   : QWHITE13.ZIP

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ID:LC QEMM-386: Getting Large Contiguous Regions of High RAM
Quarterdeck Technical Note #244 Filename: LARGCONT.TEC
by Greg Goode CompuServe: LARGCO.TEC
Last revised: 6/08/92 Category: QEMM

Subject: Large, single contiguous regions of High RAM are typically more
advantageous than several smaller ones. This note explains how to
configure your system to maximize the size of your High RAM regions.

So you want large contiguous regions of High RAM for TSRs and device drivers
that don't have enough space to load high? Well there are many methods for
getting those large High RAM regions.

Use QEMM-386's Stealth feature. QEMM-386's Stealth feature is only available
with QEMM-386 versions 6.00 and above. Stealth hides your PC's ROM code and
maps High RAM into the ROM address space, which is then available for loading
TSRs and device drivers. For more information on using QEMM-386's stealth
feature, see your QEMM-386 manual. If you have trouble using Stealth, get
Quarterdeck's Technical Note #205, "Trouble-shooting Stealth."

This technote gives detailed information regarding the use of QEMM-386's
Stealth feature, and provides tips for using Stealth on your system.
Technotes may be obtained from the Quarterdeck BBS (310-314-3227), by calling
QFAX (our automated FAX-back service, at 310-314-3214: call and request by
number), on Compuserve (GO QUARTERDECK, library 2), or BIX. Many technotes
are also available on large local BBSs, often in "DESQview" or "multitasking"
file areas.

If you are using a version of QEMM-386 that does not support the Stealth
feature, there are other methods for gaining those large High RAM regions. If
the applications that you use do not need expanded memory, you can disable
QEMM-386's ability to provide expanded memory. Since expanded memory is
accessed via a 64k page frame, by disabling expanded memory you will gain 64k
of High RAM. To disable expanded memory, you must add the FRAME=NONE parameter
to the line that loads QEMM-386. This line is located in your config.sys
file. The line that would need editing looks something like this:


Disabling expanded memory in the above example would make the line look like


Please note that adding the NOEMS parameter to the QEMM-386 line will mean
that your system will be unable to use expanded memory. You will also be
unable to use QEMM-386's Stealth feature, since this option requires an EMS
page frame.

Another method for gaining more High RAM, and potentially larger High RAM
blocks is to run through QEMM-386's Analysis procedure. Analysis suggests
command line parameters that could be given to QEMM-386 to more efficiently
use high memory. For more information on QEMM-386's Analysis, refer to
Manifest manual (look in the "Analysis" section of the "QEMM" chapter or the
QEMM-386 manual (look in the "Analysis" section of the "QEMM.COM" chapter).

The above 3 methods for getting larger High RAM regions involve increasing the
amount of High RAM available. But you may have plenty of High RAM, but
because it is broken up into different High RAM regions, no one region is
large enough to initialize and load your large TSRs or device drivers. This
may be due to the hardware on your system using high memory addresses for
their own use. Many adapters (such as network cards and disk controllers) use
addresses into which QEMM-386 could map High RAM, and the area that they use
could be right in the middle of what would otherwise be a large High RAM

Fortunately, many adapters have the ability to change which area of High RAM
they occupy. For example, suppose you have a network card that is configured
to use the address space D000-D3FF for its adapter ram. Let us further
suppose that you have 32k of High RAM available from C800-CFFF and 48K of High
RAM available from D400-DFFF. If you were to move the network adapter's 16k
of adapter ram to C800-CBFF, the previously used address of D000-D3FF would
become available as High RAM. Hence, the entire 80k region from CC00-DFFF
would become available as one large High RAM block.

Using the techniques described above could potentially give you a single
contiguous High RAM region as large as 191 kilobytes.

* Trademarks are property of their respective owners. *
*This technical note may be copied and distributed freely as long as it*
*is distributed in its entirety and it is not distributed for profit. *
* Copyright (C) 1992 by Quarterdeck Office Systems *
************************ E N D O F F I L E *************************