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1990-08-30
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ID:AB Intel AboveBoard Plus
Quarterdeck Technical Note
by Stan Young
Q: How do I set up my Intel AboveBoard Plus to best support
DESQview or for use with QRAM?
The Intel AboveBoard Plus supports in hardware many of the features of
the EMS 4.0 software specification that DESQview and QRAM would like to
use.
It is capable of mapping EMS memory below the 640K barrier to support
DESQview's multitasking. It also can map EMS memory into high memory
addresses above 640K and below 1 Megabyte, a feature which is useful to
both DESQview and QRAM in order to get more DOS memory.
Obtaining these features, however requires that the board be set up in
specific ways, and there are some restrictions in the way the board and
driver work that are important to understand.
1. Backfilling Motherboard Memory:
Backfilling motherboard memory is NOT important to the operation of
QRAM. But, as in the examples given in Appendix B of the DESQview manual,
for Enhanced Expanded Memory Boards if you want to have large expanded
memory partitions in which you can multitask programs, it is necessary to
disable motherboard memory and have the AboveBoard Plus fill memory out to
640K. The lowest the AboveBoard Plus will place EMS4 pages is from 256K,
so it is not to your advantage to backfill any lower than that, even if
your machine will support backfilling from a lower address. If your
machine will allow the board to fill out from 256K, you will be able to get
expanded memory partitions of 384K. Unlike the examples in the manual shown
for EEMS cards, the partitions will be 384K regardless of the type of video
card you have, as the Intel hardware will not allow for any EMS expanded
memory pages to be mapped into the video areas.
Once the board is backfilling motherboard memory addresses, one very
important configuration item remains relative to the driver. You must
specify the "MC" (Map Conventional) parameter to the EMM.SYS driver.
Reference to this parameter is somewhat buried in the Intel manual, but
this parameter must be specified in order to have the driver set expanded
memory pages in the 256K-640K range.
2. Set the "Page Frame" as low as possible:
This is important for BOTH DESQview and QRAM users. The AboveBoard Plus
driver will only map memory above 640K as one contiguous block, starting
with the original 64K EMS page frame. For any other memory to be mapped,
it must be directly above and contiguous with the page frame. This might
be changed in a future release of the driver, as other EMS 4.0 drivers are
not so restrictive as to where the additional memory resides.
Because of this requirement, and because some versions of the Intel
installation program default the page frame to a "D000" address, memory
addresses that might be mapped are often bypassed. To get best use from
the memory, set the page frame as low as possible.
The AboveBoard driver which became available when Intel started shipping
QRAM with its boards defaults the frame to the lowest possible address.
Upgrade drivers are available from Intel directly and are posted on Intel's
electronic bulletin board.
If you do not have such a driver, we have determined that the easiest
way to be sure the frame is low is to change the CONFIG.SYS file so the the
frame assignment (usually D000) is set to C000. While it is often the case
that a C000 page frame setting might be in conflict with video ROMS or
other installed devices, it is our observation that the Intel driver
generally detects these devices and on boot will determine that the setting
is inappropriate and will select instead the lowest frame setting that is
free -- just what we wanted. This method, while easy, may not be
foolproof, so if you encounter difficulty with the frame the Intel driver
selects, you will have to do some digging into your hardware documentation
to see what area might be available.
3. Install the QEXT.SYS driver:
Assuming you have an AT, you can configure some of the Intel AboveBoard
Plus memory as exTENDed memory. By loading the QEXT.SYS driver in your
CONFIG.SYS file (see page 148 in the DESQview manual), this driver allows
you to take 60K of extended memory and make it available for running some
of DESQview's code, thus lowering the overhead of DESQview in DOS and
increasing your Maximum Available Conventional Memory by 60K as shown by
the Memory Status program.
Early versions of the AboveBoard Plus only allow you to configure
extended memory in increments of 512K, so on these systems, you have to
reserve 512K of extended memory to support the 64K QEXT driver. The
remaining memory might be used as a VDISK, or by a disk cache, but will not
be available as expanded memory. Intel has recently begun shipping boards
which can allocate memory in 128K segments, and an upgrade for existing
boards is available.
If you have other extended memory on the machine, you may not want to
allocate any of the AboveBoard as extended memory. You would simply install
the QEXT.SYS driver and as long as the extended memory starts at 1 megabyte
(1024K), QEXT will use it.
As is usual, when using an expanded memory system, you will want to load
DESQview using the XDV.COM loader as indicated on page 139 of the DESQview
manual. The settings above should allow you to get the best memory sizes
for DESQview. Your Memory Status program will probably show figures
somewhat less than listed in the DESQview manual. This is because the
AboveBoard Plus will not map into the video memory area, but the memory
obtained in the windows should be adequate for most purposes.
Intel Tech Support: 800-538-3373
Intel BBS: 503-645-6275
Intel Support FAX back: 503-629-7576
Copyright (C) 1990 by Quarterdeck Office Systems
* * * E N D O F F I L E * * *