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

 
Output of file : ACCESSED.TEC contained in archive : QWHITE13.ZIP

ID:TA QEMM: Type and Accessed Screens
Quarterdeck Technical Note #169 Filename: ACCESSED.TEC
by Al Huck CompuServe:
Last revised: 2/23/92 Category: QEMM

Subject: Using QEMM.COM's Type and Accessed screens to detect possible memory
conflicts.


Q: How can I use the Type and Accessed screens of QEMM.COM to detect possible
memory conficts?

Start by changing the QEMM386.SYS line in the CONFIG.SYS file to the
following:

DEVICE=C:\QEMM\QEMM386.SYS ON MA=0

Reboot your computer and try to duplicate the problem. If the problem does
not recur, get to a DOS prompt. Type CD \QEMM (your QEMM directory) and press
the ENTER key. Next, type in the following line and press the ENTER key.

QEMM TYPE MAP

The following screen will appear.

QEMM TYPE SCREEN

n=0123 4567 89AB CDEF + = Mappable
0n00 XXXX XXXX XXXX XXXX * = Rammable
1n00 ++++ ++++ ++++ ++++ F = Page Frame
2n00 ++++ ++++ ++++ ++++ H = High RAM
3n00 ++++ ++++ ++++ ++++ M = Mapped ROM
4n00 ++++ ++++ ++++ ++++ X = Excluded
5n00 ++++ ++++ ++++ ++++ V = Video
6n00 ++++ ++++ ++++ ++++ A = Adapter RAM
7n00 ++++ ++++ ++++ ++++ R = ROM
8n00 ++++ ++++ ++++ ++++ / = Split ROM
9n00 ++++ ++++ ++++ ++++
- An00 VVVV VVVV VVVV VVVV
- Bn00 ++++ ++++ VVVV VVVV
- Cn00 RRRR RRRR ++++ ++++
- Dn00 ++++ ++++ ++++ ++++
- En00 FFFF FFFF FFFF FFFF
- Fn00 RRRR RRRR RR** RRRR

The area marked with "-" to the left is the "reserved area". This is where
the memory conflict is probably occurring. The "reserved area" is where
devices such as disk controllers, video boards, network cards etc. reside and
QEMM's job is to determine exactly how much of this area is unused and reclaim
this free space for additional memory. We will concentrate on this area.

Changing the RAM parameter to ON tells QEMM-386 not to overwrite any addresses
in the reserved area in order to create High RAM. Therefore, no High RAM will
exist, and the program or device driver that is accessing this area will not
cause a conflict. The areas marked with "+" and "*" on the chart below
(copied from our QEMM TYPE screen above) are not being used by QEMM-386 right
now. If one of these areas is already in use, QEMM-386 isn't able to detect
it yet. Our procedure will aid us in informing QEMM-386 that something is
there, even if QEMM-386 can't see it.

n=0123 4567 89AB CDEF

- An00
- Bn00 ++++ ++++
- Cn00 ++++ ++++
- Dn00 ++++ ++++ ++++ ++++
- En00
- Fn00 **

Write these locations down. Next, Type in the following command:

QEMM ACCESSED MAP

The following screen will appear.


QEMM ACCESSED SCREEN

n=0123 4567 89AB CDEF U = Unaccessed
0n00 WWWA AAAA AAAW WWWW A = Accessed
1n00 WWWU UAUW UUUU WWWA W = Written
2n00 AAAA AWAU WWWW WAUU
3n00 WWUU UUUW WWUU UUUU
4n00 UUUU UUUU UUUU UUUU
5n00 UUUU UUUU UUUU UUUU
6n00 UUUU UUUU UUUU UUUU
7n00 UUUU UUUU UUUU UUUU
8n00 UUUU UUUU UUUU UUUU
9n00 UUUU UUUU UUUU UUUU
- An00 WWAA AAAA AAAA AAAA
- Bn00 WAUU UUUU WWWW WWWW
- Cn00 WWWW WWWW UUUU UUUU
- Dn00 UUUU UUUU UUUU UUUU
- En00 UUUU UUUU UUUU UUUU
- Fn00 AUUA WAAU UAUU WAAW


Again, like the TYPE screen we are only concerned with the reserved
area ( - ). And we are only interested in the areas that were
marked with the "+" or "*" on the TYPE screen. Example:

n=0123 4567 89AB CDEF

- An00
- Bn00 WAUU UUUU
- Cn00 UUUU UUUU
- Dn00 UUUU UUUU UUUU UUUU
- En00
- Fn00 UU


All of the areas that were marked "+" or "*" on the Type screen should be
Unaccessed (U). If something has been Written to (W) or Accessed (A), then
that is where the conflict is occurring. Notice in this example on the Bn00
row, that the 0 and 1 column have a W and A. This is where the conflict is
happening in this case. To solve this problem, simply add the following
EXCLUDE, or X, parameter to the QEMM386.SYS line in the CONFIG.SYS file:

|<-added--->|
DEVICE=C:\QEMM\QEMM386.SYS RAM X=B000-B1FF

QEMM-386 will now be able put High RAM in the remainder of the reserved area
and will not conflict with the device or program that is using the part we
excluded from QEMM-386's use.

The way we found B000-B1FF to be the problem is by looking at row Bn00, Column
0 and 1 where the "W" and "A" are displayed. The top of this screen says the
following.

n=0123 4567 89AB CDEF

Replace the "n" of Bn00 with the number on top. B000 and B100 are the starting
hexadecimal addresses for these blocks. The B000 block starts at address B000
and ends at address B0FF. The B100 block starts at B100 and ends at B1FF. All

blocks start at ??00 and end at ??FF. Because the blocks causing the problem
in the example were right next to each other, we excluded both blocks at
once, starting at the beginning of the first and stopping at the end of the
second.

If after reading this technical note, you still have problems with High RAM,
call our technical support team. Here are some ways to contact Quarterdeck
Technical Support:

Technical Support (310) 392-9701
BBS (310) 314-3227
CompuServe "GO QUARTERDECK"
FAX (310) 314-3217
Q/FAX (310) 314-3214 (Automatic FAX download service:
call from your fax-machine telephone)

************************************************************************
* 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) 1993 by Quarterdeck Office Systems *
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