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Using QEMM's Analysis Procedure to Find Memory Conflicts
This QEMM 7 technote is an abridged version of a technical
bulletin that is available through our standard support channels.
The information contained in this version pertains ONLY to QEMM
version 7.0. If you need information relating to earlier versions
of QEMM or if you are interested in a lengthier discussion of this
subject, you can obtain the unabridged version from the following
sources:
Quarterdeck Technical Support BBS: EXCLUDE.TEC
CompuServe: EXCLUD.TEC
Q/FAX: #239
Subject: Finding potential conflicts in the address space between
640K and 1MB by using QEMM's Analysis procedure. An important
note for users on network workstations.
The purpose of this document is to explain the use of QEMM's
ANALYSIS feature. ANALYSIS is a procedure used to find address
space between 640K and 1024K that is used by your hardware (or,
in rare cases, by software programs) but whose use is undetected
by QEMM during bootup. To prevent memory conflicts, these areas
must be excluded explicitly on the QEMM386.SYS line of the
CONFIG.SYS. PLEASE NOTE: If you are using Stealth ROM, you
should refer to our Stealth ROM troubleshooting technical
bulletin STEALTH.TEC.
WHAT IS ANALYSIS?
Whenever QEMM is "on" it monitors the use of the first megabyte
of address space. The QEMM/ANALYSIS screen of MANIFEST points
out portions of the address space that need to be excluded from
QEMM's use because they are being used by a hardware device
installed in your PC or by a piece of software you are running.
Such addresses are indicated on the ANALYSIS screen by the letter
X (which appears red on color monitors.)
WHY SHOULD I USE ANALYSIS?
If you are getting an Exception #13 error message, are unable to
access your network when QEMM is installed, cannot access a
floppy, use your printer, or run some program, are experiencing
lock-ups at some identifiable point in operating your computer
(from booting the system to running your word processor), or have
some other problem when running QEMM that you do not have when
you do not run QEMM, then the ANALYSIS procedure may be a useful
diagnostic process.
You may also want to use ANALYSIS in order to find address space
that is NEVER accessed by your hardware or software so that these
areas can be INCLUDED for QEMM's use, increasing your available
High RAM.
WHY IS THIS NECESSARY?
This procedure may be necessary at times because some Adapter
ROMs and Adapter RAMs do not identify themselves in such a way as
to be detected properly by QEMM. Adapter ROMs are supposed to
identify their length in the third byte of the ROM itself, but
sometimes report a smaller size. Adapter RAM that is not active
at bootup time looks exactly like unoccupied address space. QEMM
maps memory into unused address space between 640 and 1024K, and
will map over such adapter ROMs and RAMs.
Also, some special CGA video cards have two pages of video: one
at B800-BBFF, the second at BC00-BFFF. QEMM may map over the
second page, causing a conflict if you run a program that tries
to use the second page. In rare situations a program may use
portions of the upper address space directly.
HOW DOES ANALYSIS WORK?
The QEMM/ANALYSIS screen of MANIFEST is a cross-reference between
the QEMM/TYPE and QEMM/ACCESSED screens. The TYPE screen shows
who QEMM thinks is using the address space: Video, ROM, Page
frame, High RAM, etc. The ACCESSED screen shows whether the
address space has been accessed. The ANALYSIS screen reports
that address space should be excluded from QEMM's use when ALL of
the following conditions exist:
1) QEMM is not itself accessing the upper address space (as it
will when the RAM parameter is on the QEMM386.SYS line of the
CONFIG.SYS.
2) QEMM is finding that some portion of the address space is
being accessed.
3) QEMM is not detecting the existence of a video card, ROM,
adapter RAM or ROM, or the like in this same portion of the
address space, but is finding it "mappable" instead.
How do I use ANALYSIS to find EXCLUDEs?
1. The first step is to determine if QEMM's Stealth ROM feature
is enabled. At the DOS prompt, type QEMM and press Enter.
A report summarizing QEMM's status is displayed. If you see the
line Stealth Type = M or Stealth Type = F, Stealth ROM is
enabled; make a note of the mode being used (M or F.)
2. Use a text editor to edit your CONFIG.SYS file and type REM
followed by a space at the beginning of the line that starts as
follows:
DEVICE=C:\QEMM\QEMM386.SYS (REM causes the line to be ignored).
The line should look something like this:
REM DEVICE=C:\QEMM\QEMM386.SYS (parameters not shown)
3. Add a new line directly below the line you just edited. What
the line says depends on whether Stealth ROM is enabled on your
system.
If you are using Stealth ROM: Add the following line,
substituting the appropriate Stealth ROM letter, M or F for the x
in ST:x.
DEVICE=C:\QEMM\QEMM386.SYS ON MAPS=0 ST:x FSTC:Y
If you are not using Stealth ROM: Add the following line:
DEVICE=C:\QEMM\QEMM386.SYS ON MAPS=0
4. Save your CONFIG.SYS file and reboot your PC.
Now you are ready to use the program or device that has been
giving you trouble since you installed QEMM. If the problem is
with a piece of software, run that program and access the
features you normally use. If you are having trouble with a
particular hardware operation, perform that operation.
If you are attempting to find addresses that can be INCLUDED for
QEMM's use, use every piece of software that you might use during
the course of your workday and use as many features as possible.
Access every hardware device. If you use DESQview, run it but
then exit without running any programs inside of it.
PLEASE NOTE: The new QEMM line you added for the Analysis
procedure did not include the RAM parameter. That means you no
longer have High RAM, so device drivers and TSRs will load low
and you will not have as much conventional memory to run
programs. We will add the RAM parameter back later.
5. Without rebooting your computer, run Manifest by typing MFT at
the DOS prompt. Look at the QEMM/ANALYSIS screen. If you see
any "X's" these areas must be excluded by adding an appropriate
EXCLUDE statement to the QEMM device line. If you see "I's" you
can try to INCLUDE them. The green "I's" that you see on the
QEMM/ANALYSIS screen indicate that this portion of the address
space has not been accessed by anyone YET and QEMM is not mapping
this portion of the address space. It is quite possible that
this portion of the address space will be accessed later. (As an
example: The portion of the system BIOS ROM that contains the
code for controlling the floppy drive may report that it is
includable until you actually use the drive. If you INCLUDE it
you will have no problem until you access a floppy.) In essence
what Manifest is saying is "You may be able to use these upper
memory addresses to load drivers and TSR's. But maybe not." If
you notice any problems after adding INCLUDEs, remove them one by
one until you determine which you can safely use.
6. Our final step is to edit the CONFIG.SYS file. Delete the
word REM from the original QEMM386.SYS line. Then use EXCLUDE
statements to prevent QEMM from mapping memory into addresses
used by your devices and/or software, as determined by the
ANALYSIS procedure. If the ANALYSIS screen suggested areas to be
INCLUDED, add INCLUDE statements also. If you are not sure of
the correct syntax to use for INCLUDE and EXCLUDE statements,
refer to your QEMM manual.
Delete the QEMM device line we created for our ANALYSIS, then
save the new CONFIG.SYS file and rerun Optimize. (This is
necessary whenever you do something which alters your regions of
High RAM.)
CAN ANALYSIS FAIL?
Some hardware devices may use upper address space, but only
momentarily. For instance, there is a Bernoulli drive that has
an Adapter ROM that goes in the upper address space. When the
device driver for the Bernoulli Box loads it searches for itself
at the beginning of every 8K portion of the address space
beginning at C800. If the Adapter ROM happens to be located at
DC00, then the device driver will access every other 4k of the
address space from C800 to DC00, causing Xs to appear on the
ANALYSIS screen every other block in this area. These areas,
however, are only being used during the searching process and
need not be excluded except, possibly, the DC00-DEFF, where the
Adapter ROM of the Bernoulli actually resides. In such a case,
it would be necessary to experiment with each exclude in order to
find out what exclusion is really needed.
Additionally, QEMM is not active while you are running Microsoft
Windows in its 386 Enhanced mode and the ANALYSIS process is not
useful for the period of time that you are in Enhanced Mode.
WHAT IS THE COST FOR EXCLUDING AN AREA OF UPPER MEMORY?
EXCLUDing a portion of the address space will cost you some
usable High RAM. It will not make your system malfunction in any
way. While you do not want to forfeit any usable High RAM by
excluding a larger area of upper memory than necessary, failing
to exclude an area used by your hardware can cause your system to
lock up or malfunction in some other way.
SUMMARY
QEMM does its best to identify upper memory address space that is
being used by your hardware and software, but is not always 100%
successful. ANALYSIS is a tool to allow you to identify address
space between 640K and 1024K that is being used by your hardware
(or, in rare cases, by a piece of software) which cannot be
identified through the documentation accompanying the product.
******************************************************************
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) 1990-93 by Quarterdeck Office Systems
******************** E N D O F F I L E ***********************