New Star Software Collection/NSS_Collection.iso/3-069 qemm 603/1.ima/DVMAN/APPEND-B.DEV

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Appendix B

Using DESQview with Expanded Memory, Extended Memory, or a 386 PC

The most important resources available to DESQview are the speed of your
computer and the amount and type of memory you have installed.  The faster
your PC is, the more quickly DESQview (or any other program) can perform
its functions.  But speed is not DESQview's most critical resource; memory
is.  How much memory you have, and how that memory is configured is very
important to DESQview.  The reason is that most programs written for DOS
2.x to 4.x may access only the first 1024K (one megabyte) of memory, and
typically they only use the first 640K, since the other memory areas are
resvered for special functions.  The maximum amount of memory that most
programs and data can occupy is 640K, including DOS.

When you run a single program on your PC, 640K is the maximum size of DOS,
your program, and its data.  So, on a 640K system, the size of the largest
single program you can ever run inside DESQview is about 430K ~dash~
because DOS takes approximately 60K and DESQview takes about 150K.

If you run multiple programs, 430K is the maximum size of all the programs
you can run concurrently, including all their data.  (The term concurrently
means that multiple programs are both loaded into the 0K-640K area of
memory and may run simultaneously in this area.)  This amount of memory can
be very limiting for many of today's DOS programs, so ways of reducing DOS
and DESQview overhead are often used in order to increase the size of
memory available for each program.

~Subhead~ ExTENDed Memory

 The first 640K of memory is called conventional memory.  An 80286 or 386
or i486 PC can also have many megabytes of another type of memory, called
exTENDed memory.  ExTENDed memory begins at 1024K and continues from there;
it is NOT located between 640K and 1024K.  A new classification of
programs, using a "DOS extender" can actually run in exTENDed memory and
use some of the lower 640K to handle their work with DOS.  These programs
are specially written to be DOS extended by the program's developer.  Lotus
1-2-3 Release 3 is an example of one such program.  Except for DOS extended
programs, exTENDed memory is severely limited in utility by the fact that
most existing DOS programs can't use it, either to run themselves or to
store data.

DESQview, however, is an exception ~dash~ it can run 64K of itself in the
first 64K of exTENDed memory.  So, if you have an 80286 or 386 PC with
exTENDed memory installed, DESQview's overhead (in conventional memory)
drops by 64K to about 85K ~dash~ and the largest program you run
accordingly increases by 64K to 495K.  DESQview was the first DOS program
to use this area.  Other programs have now also been modified to use it as
well.  The first 64K of exTENDed memory is usually called the "High Memory
Area" (HMA), and may be used by only one program.

~Subhead~ ExPANDed Memory

 In order to access more than 640K on all types of DOS computers (including
8088 and 8086), another type of memory was invented ~dash~ called exPANDed
memory (EMS). It is possible to both store data and run programs in
exPANDed memory, but only when the memory is configured properly and
managed effectively.  DESQview can manage exPANDed memory for multiple
programs, even if those programs have not been modified to understand
expanded memory themselves.  It is the "control program" you need to
actually make use of all the capabilities of the EMS memory technology.

~Subhead~ 386 or i486 PCs

 On a 386 or i486 PC, you DO NOT need a special EMS memory board.  All you
need is standard 386 exTENDed memory, Quarterdeck Expanded Memory Manager
386 (QEMM-386), and DESQview.  QEMM-386 converts a 386 or i486 PC's
exTENDed memory into expanded memory.  DESQview acts as the "control
program" to take advantage of the ability of the 386 PC's virtual 86
machine architecture to emulate EMS memory.  To DESQview and QEMM-386, an
80386SX or i486 PC has the same memory management features as a 386 PC.

~Subhead~ Determining the Largest Program Size in DESQview

 The table below shows how having EMS memory or a 386 PC, DESQview can
reduce its overhead substantially ~dash~ even to zero in some cases ~dash~
by loading part of itself in both exTENDed and EMS memory.  Your values may
be slightly smaller or much larger depending on your use of the LOADHI
programs which come with QRAM and QEMM.

~Subhead~ About this Appendix

 Below is the table of contents for the rest of this appendix.  All of you
should read the first three sections, pages 135-139.  The Expanded Memory
Technology is for the more technically minded ~dash~ and can be skipped if
you're not interested in the details.  Optimizing How DESQview Uses EEMS
Memory and Reducing Your System's Memory aren't mandatory reading either,
but you may need to take some of the steps described in these sections to
get the Largest Program Size listed above.

 DESQview's power increases when you add an expanded memory board to your
PC, PC-XT, or PC-AT, or when you run DESQview on a 386 PC in conjunction
with Quarterdeck Expanded Memory Manager 386

~Begin footnote~

If you use a 386 expanded memory manager other than QEMM-386 (such as the
Compaq Expanded Memory Manager), you may not be able to take advantage of
all of DESQview's 386 PC capabilities.

~End footnote~

(QEMM-386).  There are two standard types of expanded memory.  DESQview
supports both:

~Item~ Expanded memory that follows the Lotus/Intel/Microsoft Expanded
Memory Specification Version 3 or Version 4.  This is usually abbreviated
as EMS memory, EMS3 memory, EMS4 memory, LIM memory, or sometimes LIM-EMS
memory.

~Item~ Expanded memory that follows the AST/Quadram/Ashton-Tate Enhanced
Expanded Memory Specification.  This is usually abbreviated as EEMS memory
or sometimes enhanced-EMS memory.

Memory boards which were originally designed for EMS3 can have an EMS4
driver written for them, but they will not gain all of the new features of
EMS4 because they lack the necessary hardware to perform the advanced
functions such as mapping more than 64K of memory at one time.  EEMS memory
boards can become EMS4 memory boards by simply obtaining an EMS4 software
driver from the manufacturer, because the extra hardware necessary for the
advanced functions is built into EEMS boards.  Almost all references to
EMS4 in this manual apply to EEMS as well.

The extra DESQview capabilities available to you are directly related to
the amount and type of expanded memory you have.  DESQview uses either type
to its fullest potential and automatically detects its presence, as long as
you've loaded an expanded memory manager~dagger~ (EMM) when you booted your
system.

DESQview is not compatible with expanded memory emulators on 80286 PC's
which convert exTENDed memory or disk space into exPANDed memory without
additional hardware.  These programs use significant amounts of memory
below 640K and are not fast enough to perform effectively with DESQview.

~Subhead~ Determining If You Have Expanded Memory

 You have expanded memory that's compatible with DESQview:

~Item~ On a PC, PC-XT, or PC-AT, only if you've purchased an expanded
memory board and installed it on your PC along with the corresponding
expanded memory manager driver program.  Examples of these are:

 ~dash~  EMS Version 3 (EMS3) boards, such as the Intel AboveBoard,
BocaRAM, and Everex RAM 3000 and others which can only use 64K of expanded
memory at any one time.

 ~dash~  Enhanced-EMS (EEMS) boards (which include EMS3 memory as a
subset), such as the AST RAMpage, AST SixPakPremium, AST Advantage Premium,
and PC Technologies RAMpartner.

 ~dash~  EMS Version 4 (EMS4) boards (which also include EMS3 memory as a
subset) such as the Intel AboveBoard Plus, All Computers CHARGECARD,
Computer Peripherals CPI-XMA, Everex RAM 8000, Newer Technologies
Concentration, STB Rapidmeg, Teletek X-Bandit, Dakota Research ???, and any
of the EEMS boards with an EMS4 driver.  These boards can access more than
64K of expanded memory at any one time.

~Item~ On a 386 PC, only if you have installed Quarterdeck Expanded Memory
Manager 386~dagger~ (QEMM-386).

 An exPANDed memory board is not the same as an exTENDed memory board.  The
similarity of names makes this a confusing point.  Unless your memory board
explicitly says that it's an expanded memory board that supports the EMS or
EEMS standard (or you have a 386 PC and QEMM-386), you don't have expanded
memory.  (See page ?qext?for information on using DESQview with exTENDed
memory.)

~Heading~ How DESQview Uses Expanded Memory

 DESQview uses expanded memory in three ways:

~Item~ As data storage, for programs that explicitly know about and use EMS
memory for data ~dash~ such as 1-2-3 Release 2 or Release 3, WordPerfect 5,
Paradox, and so forth.

~Item~ As a "swapping" area, to temporarily store programs when DESQview
needs additional space to load other programs or to save "graphics
screens".

~Item~ As program memory ~dash~ which is to say, as memory that programs
can run in.

Expanded memory can also be used for RAM disks, print spoolers, and disk
caches.  When used for these, load these driver programs before you start
up DESQview, so that all the programs you run can take advantage of their
features.

~Subhead~ Using Expanded Memory as Data Storage

 Many programs ~dash~ such as 1-2-3 Release 2 ~dash~ use exPANDed memory to
make large amounts of data available quickly.  When DESQview is used on a
system with expanded memory, it extends this capability by allowing several
programs to use expanded memory at the same time.  DESQview ensures that
each program's use of expanded memory doesn't interfere with any other
program's use of it.

 For example, you could have 1-2-3 Release 2 and WordPerfect each storing
data in expanded memory while running in its own window.  DESQview
automatically manages the allocations of expanded memory so that each
program "sees" only its own expanded memory area.

~Subhead~ Using Expanded Memory as a "Swapping" Area

 When all the programs you want to run at the same time won't fit in
memory, DESQview automatically manages memory for you by "swapping"
programs in and out as you need them.  Although swapping can be done to a
hard disk, a RAM disk, or expanded memory, it's fastest when done to
expanded memory.  Any type of expanded memory may be used for swapping.

When you start up a program, DESQview begins by finding a place in memory
for it to run.  If there's an unused area large enough, DESQview puts the
program in that area.

Programs loaded in the first 640K can run concurrently, since they're
running in the memory that DOS knows about and supports.  However, if
there's no unused area large enough for the program to fit in, one or more
of the programs already loaded are swapped out to make room ~dash~ which is
to say, they're removed from memory and stored somewhere else temporarily.

 Programs that are swapped out are frozen (suspended) ~dash~ because those
programs are no longer "in memory", where they must be for your PC to
execute them.  When you switch back to a swapped out program, it's reloaded
into memory and resumes where it left off when it was swapped out.
(Programs that can't be arbitrarily suspended ~dash~ such as communications
programs ~dash~ must be nonswappable.)

The amount of time it takes to swap one program out and another program in
is highly variable.  If you're swapping to a hard disk, the time depends on
the size of your program and the speed of your hard disk.  Hard disk times
vary enormously.  A "fast" disk may swap three or even five times faster
than a "normal" disk.

Swapping to a RAM disk is faster, but still not optimal because, even
though RAM disk is "memory", accessing it still incurs DOS overhead.  The
fastest method is swapping to expanded memory.  It's virtually
instantaneous.

~Subhead~ Using Expanded Memory as  "Program" Memory

 Although "swapping" programs to expanded memory is nice, "running"
programs in expanded memory is even better. You can run programs in
expanded memory only if you have fully hardware compatible EMS4 memory,
ENHANCED expanded memory (EEMS), or are using a 386 PC in conjunction with
QEMM-386.

Running programs in expanded memory means that you can run more programs
than would normally fit in 640K.  In fact, you can run as many programs
simultaneously as will fit in your entire expanded memory, up to 32MB
worth.  The size of each program is less than 640K (not counting the data a
program may store in expanded memory), and the total amount of memory used
for running programs can be many megabytes.

You cannot run programs in expanded memory if you have EMS3 memory.  The
reason is that with EMS3 your PC can only "see" one 64K chunk of EMS memory
at any one time while, with fully hardware compatible EMS4 memory, or EEMS,
it can "see" enough memory to run most existing DOS programs.  It is
important to note that an EMS3 board may have an EMS4 driver, but this does
not allow the extra hardware features of EMS4 such as multitasking.

However, you only get capability to run programs in EMS4 memory when
DESQview manages your EMS4 memory.  Note that DESQview runs off-the-shelf
programs in EMS4 memory.  You don't need any special versions or have to
upgrade your existing software.  The programs you now own will run in EMS4
memory as they stand.

 But, this capability doesn't come without some work on your part.  To
properly use EMS4 memory, you may need to "disconnect" some of your
conventional memory (below 640K) and substitute EMS4 memory for it.
Although you may be reluctant to "disconnect" perfectly good memory, if you
don't, you severly limit the number and size of programs you can run in
EMS4 memory.  In the worst case, you can't run any programs in EMS4 memory
~dash~ see Optimizing How DESQview Uses EMS4 Memory on page 149.  Note that
"disconnecting" conventional memory usually just involves changing switch
settings, and doesn't require you to modify you hardware.  Also, there is
no need to "disconnect" memory on a 386 PC.

~Heading~ Installing Expanded Memory

 It's not necessary to do anything special to make expanded memory work
with DESQview.  Each time you start up DESQview, it checks for the presence
of expanded memory and automatically uses it if it's available.  So, it
doesn't matter to DESQview whether you install DESQview first, expanded
memory first, or both at the same time.

~Subhead~ If You Have a PC, PC-XT, or PC-AT

 When you install an expanded memory board on a PC, PC-XT, or PC- AT, be
sure to follow the board manufacturer's instructions carefully.  You must
perform at least these four basic steps:

~Step~ Verify that the default factory switch settings are correct for your
hardware configuration and, if they're not, make them correct.

~Step~ Open up your PC chassis and install the board in an empty slot.

~Step~ Install the expanded memory manager (EMM) for the board on your boot
disk and in your CONFIG.SYS file.

~Step~ Reboot your system to load this expanded memory manager.

Although it's sufficient to follow these steps, there are additional steps
we recommend ~dash~ but that aren't mandatory ~dash~  depending on the type
of expanded memory board you've installed:

~Item~ EMS3 board.  We recommend that you use part of your EMS3 board for
swapping programs and "graphics screens".  This occurs automatically unless
you've run the Setup program and specified an explicit SWAP drive to use
(see Appendix A).  Also, you can reduce DESQview's overhead if you have 64K
of exTENDed memory (see page ?qext?) which may require you to change your
EMS board's settings if you don't already have exTENDed memory.  There's no
way to improve how DESQview uses EMS3 memory or to use EMS memory to run
programs.  This is a fundamental limitation of the EMS3 hardware design.

~Item~ EMS4 or EEMS board.  We strongly recommend that you optimize the use
of EMS4 or enhanced expanded memory by taking the following two steps:

 ~dash~  Use as much of the unused area between 640K and 1024K as can be
controlled by your board.  This means that you should be sure you are using
DV.COM (which is a copy of XDV.COM) in place of DV.EXE (the INSTALL
procedure does this for you), and possibly using QRAM from Quarterdeck (a
separate product) to move resident programs and parts of DOS into the
unused areas.

 ~dash~  "Disconnect" part of your conventional memory (below 640K) and let
your EMS4 board provide it instead.  See Reducing Your System's Memory on
page 156 of this appendix for the steps involved.

 The remaining sections of this appendix, starting on page 140, discuss how
expanded memory works and why it's advantageous to follow these steps.

~Subhead~ If you Have a 386, 386SX, or i486 PC

 If you have a 386, 386SX, or i486 PC (they're all the same to DESQview and
QEMM-386), there's no need to install a special expanded memory board
because, on a 386 PC, standard 386 exTENDed memory can act like expanded
memory.  There are only three things you must do:

~Step~ Install Quarterdeck Expanded Memory Manager 386

~Begin footnote~

Or, install the expanded memory manager supplied with your 386 PC, if it's
compatible ~dash~ such as the Compaq Expanded Memory Manager (CEMM)
supplied with the Compaq Deskkpro 386.  However, if you don't use QEMM-386,
you may not be able to take advantage of all of DESQview's 386 PC
capabilities.

~End footnote~

(QEMM-386) on your hard disk and in your CONFIG.SYS file.

~Step~ Reboot your system to load this expanded memory manager.

~Step~  Use as much of the unused area between 640K and 1024K as possible.
This means that you should be sure you are using DV.COM (which is a copy of
XDV.COM) in place of DV.EXE (the INSTALL procedure does this for you), and
possibly using LOADHI from Quarterdeck (which comes with QEMM-386) to move
resident programs and parts of DOS into the unused areas.

 If you have a 386 PC, but don't have an expanded memory manager (EMM),
contact your dealer or Quarterdeck for information on QEMM-386.

~Subhead~ Verifying That  Expanded Memory is Correctly Installed

 Once you've installed your expanded memory board (except on a 386 PC),
installed the expanded memory manager, and rebooted your system, it's
useful to be able to determine whether you've installed everything
correctly:

~Item~ When you reboot, watch the screen for information about expanded
memory ~dash~ generally in the form of a count-up as expanded memory is
tested.  If no expanded memory information appears, you've done something
wrong.

~Item~ If you're familiar with DESQview, run the Memory Status program (see
pages 160-161).  If a nonzero number appears under Total Expanded Memory,
DESQview has recognized that you have expanded memory installed.  If the
number is zero, you've done something wrong.

If DESQview won't start up, you probably have a memory conflict in the
640K to 1024K area.  See Appendix E, Troubleshooting for hints on how
pinpoint the conflicting memory area and get DV.COM (XDV.COM) to avoid it.

Something else you might want to do, for your programs that store data in
expanded memory, is to limit the amount of expanded memory the program can
use ~dash~ by entering a value for Maximum Expanded Memory Size (in K) on
the Change a Program menu for the program (see page 115).  This is
especially important for programs that immediately seize all of expanded
memory when they start up.

 REMEMBER:  An expanded memory manager (EMM) must be loaded by your
CONFIG.SYS file when you boot your system before DESQview or any other
program can use expanded memory.

~Heading~ The Expanded Memory Technology

 This section offers a brief discussion, for the more technically minded,
of how expanded memory works and of how DESQview takes advantage of the
EMS4 memory technology to run multiple, large programs concurrently.

~Subhead~ PC Memory:  an Overview

 Three types of memory can be installed on a PC:

~Item~ Conventional memory is memory between 0K and 1024K (1MB).  It's the
area of memory in which all programs must run ~dash~ because DOS 2.x/4.x
only recognizes and supports programs loaded into this area.  Even DOS
extended programs need to use some portion of conventional memory.

~Item~ ExTENDed memory is memory above 1024K (1 megabyte) on a PC-AT or 386
PC.  (You can't install it on a PC or PC-XT.)  Unlike conventional memory,
exTENDed memory has an important limitation: exTENDed memory cannot be used
for running most existing programs under DOS 2.x/4.x.  It can only be used
for RAM disks, print spoolers, and disk caches, or DOS extended programs
~dash~ with one exception.  DESQview can run 64K of itself in exTENDed
memory (see page ?qext?).

~Item~ ExPANDed memory is a special kind of extra memory.  Unlike
conventional and exTENDed memory, expanded memory doesn't occupy a specific
range of fixed addresses.  Instead, any area of expanded memory can be
instantly "substituted for" (or mapped into) a like-sized area of
conventional memory.  There are two types of expanded memory.  EMS3 memory
is used to store data and swap.  EMS4 (or EEMS) memory is used, in
addition, to run programs.

 The following diagrams illustrate the basic configurations of memory that
are possible,  ExTENDed and expanded memory are optional.

 These areas represent conventional memory ~dash~ the memory between 0K and
1024K (1MB).  The first 640K is used to run programs, and the remaining
384K is reserved for the system.

 These areas represent exTENDed memory ~dash~ the memory starting at 1MB
and continuing to the end of the available address range.  The stacking of
exTENDed memory on top of conventional memory illustrates that exTENDed
memory extends the 1MB of conventional memory.ExTENDed memory cannot be
used for running most existing programs under DOS 2.x/4.x.  It can only be
used for RAM disks, print spoolers, and disk caches, or DOS extended
programs ~dash~ with one exception.  DESQview can run 64K of itself in
exTENDed memory (see page ?qext?).

These areas represent exPANDed memory ~dash~ a special kind of extra
memory.  On a PC, PC-XT, or PC-AT, expanded memory and exTENDed memory are
physically different entities ~dash~ each requiring its own, special
hardware memory board.

~Begin footnote~

Although expanded memory boards can be configured to use part of their
memory as exTENDed memory, exTENDed memory boards cannot be used as
expanded memory ~dash~ except on a 386 PC.

~End footnote~

This is illustrated by the fact that expanded memory is a separate block
of memory that sits beside conventional and exTENDed memory.  On a 386 PC,
however, exTENDed memory can act like expanded memory ~dash~ by loading
Quarterdeck Expanded Memory Manager 386 (QEMM-386) when you boot your
system.

~Subhead~ How Conventional Memory Works

 Conventional memory is memory between 0K and 1024K (1MB).  It's the area
of memory in which all programs must run ~dash~ because DOS 2.x/4.x only
recognizes and supports programs loaded into this area.  Conventional
memory is divided into three areas:

~Item~ Motherboard memory is the basic memory that comes with every PC.
It's called "motherboard memory" because it's located on your computer's
basic system board ~dash~ the "motherboard".  It varies from 64K to 640K,
depending on your PC.

~Item~ Add-on memory is used to extend the motherboard memory when it's
less than 640K.  For example, if there's 256K on your motherboard, you
could "add on" up to 384K of additional memory.  It's also called "add-on"
memory because you must "add on" a physical memory board that contains this
memory.

~Item~ Reserved memory is the memory between 640K and 1024K (1MB).  It's
called "reserved memory" because it's reserved for use by the system ~dash~
for the ROM BIOS and hardware devices, such as display adapter boards,
network boards, and hard disk controllers.  Unused addresses in this region
have no physical memory in them.

The motherboard and add-on memories must form one contiguous block,
starting at 0K and extending to a maximum of 640K.  The reserved memory,
however, is usually a collection of disjoint areas ~dash~ depending on your
hardware configuration.

The following diagram illustrates how conventional memory is divided up.
The use of the first 640K is the same for all PCs.  The allocation of
memory in the reserved memory area, however, varies according to whether
you have a PC, PC-XT, PC-AT  or 386 PC (see the diagrams on the next page).
The address values are in hexadecimal on one side of the chart, and in
decimal on the other.

Graphic not shown

~Subhead~ Why There's a 640K Limit

 When the IBM PC was first introduced in 1981, the standard "personal
computer" was based on an 8080 processor, which could address a maximum of
64K of memory.  The IBM PC, however, was built around the 8086/8088
processor, which could address up to 1024K (1MB) of memory.

Initially, the IBM PC's designers split the 1024 in half ~dash~ 512K for
programs and 512K for the ROM BIOS and hardware devices.  Then, a short
time later, they changed their minds and "unreserved" the first 128K of the
second 512K area.  That's where the 640K limit came from: 640K=512K + 128K.
High resolution graphics adapters such as the EGA or VGA have their own
memory at 640K, this keeps programs which need graphics from using any
contiguous addresses larger than 640K.

~Subhead~ How Reserved Memory is Allocated

 Reserved memory has three main uses:

~Item~ As the area for the ROM BIOS ~dash~ that part of DOS that's built
into every PC and manages the hardware basics, such as reading the
keyboard, driving the printer, and displaying information on the screen.

~Item~ As the"screen buffer" (or "video display RAM") ~dash~ the area of
memory that stores the information that appears on the video display
monitor.

~Item~ As the area for hardware-specific ROMs ~dash~ for example, the ROM
for the enhanced graphics (EGA) display adapter and the hard
diskcontroller.

 The diagrams on the next page illustrate the way that reserved memory is
usually configured.  The LIM-Data Area is the 64K area where most programs
can "see" expanded memory.  Unused areas are used by DESQview to run
programs and parts of itself; the DV.COM program places parts of DESQview
into these unused areas.

~Subhead~ How ExTENDed Memory works

 ExTENDed memory is memory starting at 1024K (1MB).  It's only available on
286 and 386 PCs.

Unlike conventional memory, exTENDed memory has an important limitation:
exTENDed memory cannot be used for running most existing programs under DOS
2.x/4.x.  It can only be used for RAM disks, print spoolers, and disk
caches, or DOS extended programs ~dash~ with one exception.  DESQview can
run 64K of itself in exTENDed memory (see page ?qext?).

~Subhead~ How Expanded (EMS) Memory Works

 It's not necessary to understand how expanded memory works to use it,
since DESQview handles all the details for you automatically.  There are,
however, "right" and "not so right" ways to use it.  So, a basic
understanding of the concepts and processes involved can help you be sure
that you're getting the most out of your expanded memory board.

 Expanded memory is a special kind or extra or "shadow" memory.  To have
expanded memory on your system, you must purchase and install a separate
(expanded) memory board ~dash~ except on a 386 PC.  On a 386 PC, standard
386 exTENDed memory can act like expanded memory (by loading QEMM-386).

There are two types of expanded memory.  Conceptually, both work the same.
The difference is in their limitations (which are imposed by the hardware
design):

~Item~ EMS3 memory is only used to store data and to swap programs and
"graphics sceens".  Only 64K of expanded can be "seen" at one time.

~Item~ EMS4 (or EEMS) memory is also used to store data and to swap but, in
addition, it can be used to run programs because more than 64K of memory
can be "seen" at one time.

The fundamental concept to understand about expanded memory is that DOS
doesn't know it exists.  As far as DOS is concerned, there's only 1MB of
memory addresses, 0K to 1024K, but DOS does not know whether any memory is
in all of these addresses.

Given this, the way expanded memory works is basically simple.  Any 64K
chunk (which is a group of four 16K chunks) of expanded memory can be
"mapped" into an unused 64K area of reserved memory.  The key concept is
mapping.  Mapping is a technical term.  What it means is that there's
hardware on the expanded memory board that "fools" the PC into thinking
that a 64K area of expanded memory is really in the unused 64K area of
reserved memory.

This is very much like looking at the ocean through the porthole of a ship.
You can't see the whole ocean through the porthole, only the area directly
outside.  If you turn the ship, then you can see a different area of the
ocean.  The whole ocean is always there, you are just looking at a certain
piece of it at one time.

With expanded memory, if your program tells the expanded memory board to
"map" some 64K chunk of expanded memory into the 64K area of reserved
memory that starts at 784K then, when the program reads or stores data in
the 784K to 848K area, it would, instead, actually be reading or storing in
a 64K chunk of expanded memory ~dash~ as the following diagram illustrates.

Effectively, the mapped 64K area of reserved memory is a porthole onto a
larger area of expanded memory.  It's just that, when you look through the
porthole you can only "see" things that are exactly that size.  If you want
to see different "view" through the porthole you have to tell the window to
"shift views" (like turning the ship).  Then, you see only the new view you
selected.

And that's exactly how expanded memory works.  A program that's been
modified to know about expanded memory can access up to megabytes of data
by looking at it in 64K chunks.  The program might start by telling the
expanded memory manager (the program that controls the "view") that it
wants to use (view) a particular 64K area of expanded memory.  Then it
fills this area with data.  When this 64K area is full, it then tells the
expanded memory manager that it wants to use another 64K area.  The
information in the first 64K area is still there.  It just can't be
accessed until it is placed back into the viewing area.

By switching among 64K areas of expanded memory, a program can thus access
up to many megabytes of memory.  Note that no information is moved.  All
the program's data is really stored in expanded memory and available at
normal memory speeds.  It's just that only one 64K area can be accessed at
a time.

~Subhead~ How EMS4 and Enhanced Expanded Memory (EEMS) Works

 The deficiency of EMS3 memory is that most programs are larger than 64K
and thus can't run in expanded memory (since 64K is the maximum area "seen"
at one time).  They can only use it for data storage.  Two methods have
been developed to remove this restriction.  The first was the
AST/Quardram/Ashton-Tate Enhanced Expanded Memory Specification (EEMS
memory or enhanced-EMS memory).  The second was EMS Version 4.  Both EEMS
and EMS4 are supersets of EMS memory. This means that they do everything
that EMS3 memory does, in a 100% compatible way, and more besides.  The
major difference between EEMS and EMS4 is how the software driver is
accessed, and DESQview can determine the correct method automatically.
Each of these newer specifications can:

~Item~ Map an area larger than 64K (in fact any area from 16K to 1MB in
size).  This increases the amount of expanded memory which can be "seen" at
one time.

~Item~ Map several non-adjacent areas.  (An EMS3 board can only map to a
single 64K area of reserved memory.)

~Item~ Map areas of memory below 640K as well as above 640K. This is where
programs run, so if enough expanded memory can be mapped below 640K a
program can actually be run from expanded memory.

Taken together, these "enhanced" expanded memory capabilities make it
possible to run not just one, but multiple programs concurrently in
expanded memory.  The process of multitasking (letting several programs run
simultaneously by giving each a "slice" of time in turn) is now viable
because context-switching (the process of allocating these time slices) can
be done by simply changing the piece of expanded memory which is "seen"
below 640K.

 Still, to take advantage of these "enhanced" capabilities, you might think
that existing programs would have to be modified to take advantage of EMS4
(or EEMS) memory.  DESQview, however, eliminates this need.  It conceals
all the EMS4 mechanisms from the program and makes it appear (to the
program) that it's running by itself in the PC's conventional (0K-640K)
memory area.  The program doesn't know it is running from expanded memory.

~Subhead~ The Capabilities of a 386 PC

 When you have a 386 PC, the need for a separate exPANDed memory board
disappears because, on a 386 PC, standard 386 exTENDed memory can act like
exPANDed memory, and almost all of the conventional memory becomes exPANDed
memory as well. This is possible because the 80386 processor chip already
has the necessary mapping capability built in. (In contrast, none of the
conventional or exTENDed memory on a PC, PC-XT, or PC-AT can be mapped.)

~Subhead~ How DESQview Works WithExpanded Memory

 When you load DESQview, it examines your memory configuration and loads
itself to take best advantage of your specific configuration:

~Item~ PC, PC-XT, or PC-AT

 ~dash~  If you've installed an EMS3 memory board and also loaded the
exPANDed memory manager (EMM) for the board, DESQview recognizes and uses
EMS memory.

 ~dash~  If you've installed an EMS4 or EEMS memory board and also loaded
the exPANDed memory manager (EMM) for the board, DESQview recognizes and
uses either EMS4 or EEMS memory.

~Item~ 386 PC

 ~dash~  If you've loaded QEMM-386,  which makes standard exTENDed memory
act like EMS4 exPANDed memory, DESQview recognizes and uses it. DESQview
also activates its special 386 features such as screen virtualization and
program protection, thus becoming DESQview 386.

~Item~  If you have only EMS3 memory on your system:

 ~dash~  DESQview allows multiple programs that store data in EMS memory to
share the Page Frame simultaneously ~dash~ by monitoring program requests
to the exPANDed memory manager and sorting them all out so that each
program thinks it's the only program using exPANDed memory.

 ~dash~  DESQview swaps to exPANDed memory when it needs additional space
to load other programs or to save graphics screens.

~Item~ If you have EEMS or fully hardware capable EMS4 memory on your
system:

 ~dash~  DESQview additionally uses the enhanced features available to run
multiple programs concurrently.

When you start up DESQview, DESQview first examines your memory and figures
out if the area immediately above 640K is available. (It generally will be
when you have a monochrome or CGA display adapter board installed.)  If
memory is available, DESQview uses it to enlarge the 640k contiguous area
that DOS uses for running programs.

DESQview then examines the memory above your "screen buffer" and figures
out if there are any other unused areas available in high memory
(640K-1024K). If there are additional mappable memory areas, it puts part
of itself in these areas (if you've started up DESQview using DV.COM). This
frees up additional memory below 640K for running programs. (DESQview may
also run small programs in these areas, in some cases.)

The net result is that DESQview frees up the largest contiguous area below
640K it can find for running programs. DESQview examines the area between
0K and 640K to see if it is under the control of an exPANDed memory
manager. If it is, then the capabilities of running programs in the
exPANDed memory areas below 640K are enabled. The size of this area is the
"Largest Available Expanded Memory" number in the Memory Status display.

~Subhead~ How DESQview Multitasks Your Programs in ExPANDed Memory

 Assuming the optimal configuration for any PC ~dash~ where the most memory
possible below 1024K can be mapped ~dash~ DESQview can switch application
programs in and out of conventional memory to run several large programs,
even if their memory requirements, when added together, total more than
640K. Programs are not really running concurrently; DESQview is switching
between them at speeds measuring in milliseconds. How this works is by
tricking DOS into thinking each program is actually running in memory below
640, when really it is being mapped into the lower 640K from different
areas of exPANDed memory. This tremendous enhancement in memory management
is made possible by the capability to map, or substitute, one memory
address for another very quickly.

For instance, when you start Program A as the first window, all processing
is done as if it is the only program in memory and is running in
conventional memory; it is. Then, when you start another program, Program
B, it is put into exPANDed memory, however DESQview, by sleight-of-hand
known as bank-switching, makes it look like it's running in the lower 640K.
What bank-switching does is to substitute a "pseudo-address" for the
program's real memory address. (In a moment, we'll look at how DESQview, by
using the features of your memory card, actually does this.) But this can
only happen if that lower 640K is mappable. On a 386 with QEMM-386 loaded,
it always is. On other machines, it must be made available by disabling the
conventional memory and allowing the memory card to backfill that memory
with exPANDed memory.

 The advantage ExPANDed memory has over conventional memory is that the
hardware supports mapping registers. Mapping registers hold specific memory
addresses which are placemarks for particular information your application
programs want at run time. Once the data are so mapped, DESQview ~dash~ and
thus your programs ~dash~ know where to find them.

DESQview takes control of the memory mapping, tracking where it puts
information for each program. In effect, then, each program running in a
DESQview window has its own map. When the time slice switches from Program
A to Program B, DESQview looks at the area of memory where Program B's
information is stored, leaving program A's information where it was.
DESQview remembers where the information for program A is mapped so that
the next time information is needed for Program A, DESQview can find it
immediately.

Instantly, DESQview "shows" what it finds in program B's area to the memory
below 640K-the conventional program area. How it does this is to
substitute, or bank-switch one memory address for another.  The program's
real address may be in exPANDed memory, but its pseudo-address (where
DESQview shows it to DOS) is in conventional memory-below 640K: it is
mapped into conventional memory. Neither DOS nor the program know that the
information comes from exPANDed memory.

 DESQview rapidly switches back and forth between each program's assigned
exPANDed memory area each time that program is due a time slice. This
movement is managed completely and transparently by DESQview. The only time
you may be aware of it is when you see a minute hesitation in program
operation, for instance, a scrolling screen display, as DESQview gives
another window its time slice according to how you have set the ratio in
Setup or Tune Performance. DESQview knows the program's information is in
exPANDed memory, but the program does not. The program expects the
information below 640K and as far as it knows, it gets it.

 The way programs execute their tasks for you is to store and retrieve
information in memory addresses. Each piece of information is assigned an
address and when a program asks for the data at a particular address, the
memory card responds with the requested information. What DESQview, in
combination with an exPANDed memory card and a memory manager really does,
then, is to reassign, or "remap" the addresses to which the programs refer.
DESQview can move between mapped addresses at normal memory speeds and can
be pointing at information required for any number of programs ~dash~ not
at the same time, but each in turn.

The previous paragraphs describe how a normal DOS program, which only knows
about memory below 640K, is handled. DESQview also knows about programs
which have been written to use EMS. If the program itself is one which
knows how to access exPANDed memory, what it does normally is to store data
in exPANDed memory using the Page Frame. A Page Frame is a 64K block of
memory whose address is assigned by the memory manager. The page frame is
the program's "window" into exPANDed memory and is accessed at the memory
address assigned by the memory manager.

All programs which require a page frame use the same page frame inside of
DESQview, in turn. (Outside DESQview all programs requiring a page frame
also all use the same one ~dash~ the address of the page frame remains
constant, unless you change it via the memory management software.) If the
program has information stored in the page frame, DESQview saves the
information when the program's time slice runs out and restores it the next
time its time slice comes up. The program pages in and out of EMS as it
would normally ~dash~ through the page frame ~dash~ to read and write its
data. DESQview manages the program itself much like any other program, with
the exception of altering how much exPANDed memory is available if the
"Maximum Expanded Memory Size (in K)" is set in the Change a Program menu,
and additionally saves and restores any mapping the EMS-aware program may
do on its own.

The whole point of disabling memory below 640 (on a PC or AT) and
backfilling it in with exPANDed memory is so that MORE than 64K (which is
the maximum a page frame can handle) can be mapped at a time. DESQview can
make a significantly larger segment of memory visible below 640K where it
can be used to run a program. Using DESQview memory management, the whole
program is mapped at once. The important concept is that mapping is the
process that makes it appear that a program residing in exPANDed memory is
running below 640K. When that feat has been accomplished, DESQview can
change the mapping very quickly between programs: the multitasking effect.

 Programs, then actually run in exPANDed memory, when their information can
be addressed below 640K. What happens is, as each window comes up for its
time-slice, the program is visible to DOS as if it were stored in the
memory area below 640 ~dash~ and runs in exPANDed memory with a
conventional memory address. When your system is optimally configured,
DESQview can then run multiple programs, whose combined memory requirement
total more than 640K, optimally, storing the programs in exPANDed memory
and addressing them in conventional memory.

~Heading~ Optimizing How DESQview uses EMS4 or EEMS Memory

 The amount of power you get from your EMS4 or EEMS board depends on how
you configure you computer's memory. Whether you choose the best or worst
memory configuration, you can always have multiple programs active at the
same time. Your memory configuration determines how many of these active
programs are also concurrent ~dash~ that is, how many of these programs are
both loaded into memory and simultaneously able to process information in
foreground or background:

~Item~ If you install your EMS4 or EEMS board without making any changes to
your memory configuration, you're only guaranteed to be able to run
concurrently the number of programs that, collectively, fit in 535K

~Begin footnote~

The 535K value applies to a PC-AT or 386 PC with an EGA or VGA display
adapter.  With a monochrome or hercules display adapter, you get 580K. With
a CGA display adapter, you get 610K. See technical notes at the end of this
appendix.

~End footnote~

 or less on a 640K system. (535K is called the size of the "first"
program.)

~Item~ If you run one large program that takes most of the 535K3
available, you may or may not be able to run other programs concurrently,
depending on whether you can disconnect motherboard memory below 640K on
your particular PC.

~Item~ If you are able to run "other" programs, each of them will have the
same maximum size ~dash~ which is dependent on how much motherboard memory
you've disconnected.  This maximum size can vary from 0K to 528K3,  and is
called the size of the "other" program.

If you modify your memory configuration to be the best possible for your
overall hardware configuration, you are guaranteed to be able to run
concurrently:

~Item~ In the worst case (on a system with an EGA and whose motherboard
memory has been reduced to 256K), one 535K3  program and multiple 384K3
programs.

~Item~ In the best case (on a system with a CGA and whose motherboard
memory has been reduced to 128K or less), one 610K3 program and multiple
608K3 programs.

Therefore, we strongly recommend that you optimize the use of exPANDed
memory by disconnecting part of your conventional memory (below 640K) and
letting your EMS4 or EEMS board provide it instead. You also must use
DV.COM.

IMPORTANT: The memory values (535K

~Begin footnote~

The 535K value applies to a PC-AT or 386 PC with an EGA or VGA display
adapter.  With a monochrome or Hercules display adapter,  you get 580K.
With a CGA display adapter, you get 610K. See technical notes at the end of
this appendix.

~End footnote~

and so forth) used here and elsewhere in this appendix are based on the
hardware configuration described in note 3 on page 177. These values may
not be correct for your system. In fact, if you have a monochrome,
Hercules, or color/graphics (CGA) display adapter, your values will be
larger than those described. Be sure to read note 3 carefully, and also
consult the tables on pages 173-174 and the other notes in the Technical
Notes section on page 177. These values will definitely be incorrect if you
don't use DV.COM or if you load any drivers (except the exPANDed memory
manager), or any memory-resident programs when you boot or before you start
up DESQview.

~Subhead~ An Overview

 Three factors affect how optimally your system is configured for using
exPANDed memory:

~Item~ What brand and model of PC your have.

~Item~ What type of display adapter board (monitor) you have.

~Item~ If you're not running a 386 PC, how much memory you have installed
below 640K.

Based on these considerations, the optimal configuration is 64K IBM PC-XT
or a 386 PC with a color/graphics (CGA) display adapter. However, this does
you little good if you don't have this configuration. As a practical
matter, optimizaton is confined to modifying the amount of memory installed
below 640K.

As noted above, if you don't make any changes to your memory configuration,
you're always able to run concurrently any number of programs that,
collectively, fit in 535K~dagger~ or less. Only when you run a large
program, or otherwise fill the 535K3, does your memory configuration make
any difference.

If you have a PC or PC-AT for which it's impossible to disconnect any
memory below 640K, no programs can run in exPANDed memory.  The size of the
programs that can run in exPANDed memory is directly related to the amount
of memory below 640K that's been disconnected and supplied by your EMS4 or
EEMS board instead. The purpose of disconnecting memory is to open up a
large "porthole" below 640K into the exPANDed memory board. The larger the
"porthole" below 640K, the more memory available to run a program in the
exPANDed memory.

The goal of optimization is to maximize the size of the "other" programs
you run, after you fill the first 535K3. (Each of these "other" programs
has the same maximum size.) The two primary factors that determine this
maximum size are the display adapter board you're using and the amount of
memory below 640K you've disconnected and let your EMS4 or EEMS board
provide instead.

~Subhead~ How the Brand and Model of Your PC Affect Optimization

 The brand and model of your PC affect how much you can optimize your
system. Although all PCs have the same basic structure, hardware details
differ. For optimization, you need to know the minimum amount of
motherboard memory your PC can have. This sets the limit for how much
memory you can disconnect, because you usually can't disconnect all
motherboard memory.

Most IBM and Compaq machines can have a minimum motherboard memory of 256K.
On Microchannel Architecture PS/2 computers such as the PS/2 Model 50 or
60, all of the motherboard memory can be disabled and filled in with
exPANDed memory automatically when using QEMM-50/60, another product of
Quarterdeck. If you have another brand or model of PC, you must consult the
technical manual for that PC (or your dealer or the PC's manufacturer) to
determine its minimum motherboard memory configuration.

~Subhead~ How Your Display Adapter Board Affects Optimization

 The type of display adapter board installed on your PC also affects how
much you can optimize your system ~dash~ because each different type of
display adapter board uses a different amount of memory in the 384K of high
memory between 640K and 1024K. DESQview will use whatever high memory
addresses the display adapter doesn't use to expand the area in which you
can run programs.

The amount of high memory that DESQview can use to run programs is affected
by the type of display adapter board you have:

~Item~ If you have a monochrome or Hercules display adapter board, DESQview
can use 64K of high memory to run programs.

~Item~ If you have a color/graphics (CGA) display adapter board, DESQview
can use 96K of high  memory to run programs.

~Item~ If you have an enhanced graphics (EGA) or Video Graphics Array (VGA)
display adapter board, there is no additional high memory available for
DESQview to run programs unless you are not using any graphics.  f you are
not using any programs which use graphics, then the VIDRAM program
available with QRAM, QEMM-50/60, and QEMM-386 can recover up to 96K more
memory from the video area that can then be used to run programs .

Also, DESQview may use other parts of high memory to run parts of DESQview
itself ~dash~ depending on your particular hardware configuration and the
capabilities of your exPANDed memory manager. For example, if you are using
an EGA or VGA adapter and a color monitor, DV can place up to 32K of itself
in the area reserved for the monochrome display (since that area isn't
being used). The area is only available if your exPANDed memory manager
controls it, though.

~Subhead~ How Your Memory Configuration Affects Optimization

 As discussed in the section, The Expanded Memory Technology, a fully
hardware capable EMS4 or any EEMS board achieves its power over an EMS3
board by virtue of three additional capabilities that an EMS3 board doesn't
have:

~Item~ An EMS4 or EEMS board can map any area of memory between 0K and
1024K (1MB), whereas an EMS3 board can map only a fixed 64K area which must
be in high memory.

~Item~ An EMS4 or EEMS board can map multiple, non-adjacent areas
simultaneously, whereas an EMS3 board can only map a single, 64K area.

~Item~ An EMS4 or EEMS board can map any area from 16K to 1MB (in 16K
increments), whereas an EMS3 board can only map four, contiguous 16K areas.

However, there is a limitation to EMS4 or EEMS memory.  An EMS4 or EEMS
board can only map an area of memory for which it supplies the RAM. It
cannot map areas of memory already filled in by your PC's motherboard,
network adapter, disk controller, or by an add-on or exTENDed memory board.

For example, if you have 512K of conventional memory and let EMS4 or EEMS
memory provide the missing 128K (to make 640K), only a single program can
use the 512K area ~dash~ because it isn't EMS4 or EEMS memory and therefore
can't be mapped.  On the other hand, if you disconnect 256K of conventional
memory and let EMS4 or EEMS memory supply 384K (256K+128K), only 256K is
restricted for use by a single program. The size of multiple programs that
can be running simultaneously in exPANDed memory therefore increases from
128K to 384K ~dash~ as the diagrams on the opposite page illustrate.

Therefore, if you have an EMS4 or EEMS board, it may be to your advantage
to disconnect part of your motherboard memory and remove any add-on boards
from your system. (There is no advantage in doing this if you have an EMS3
board or a 386 PC.)

The optimal configuration occurs if you disconnect all your conventional
memory. Then, all of conventional memory would be mappable and multiple
programs up to 528K3 could be run simultaneously in exPANDed memory. But,
you can't really disconnect all the memory on most PCs, PC-XTs, and PC-ATs
~dash~ because there is no provision for a 0K system.  However, on a 386 PC
you always get the optimal configuration ~dash~ because all of standard 386
memory can be mapped, right down to 0K.

 You don't get the full 640K in the optimal configuration because DOS,
device drivers, memory-resident programs, and parts of DESQview still
occupy part of lower memory and can't be mapped. See note 3 on page 177 for
an explanation of where the 535K value comes from. This value may not be
correct for your system. Be sure to read note 3 carefully, and also consult
the tables on pages 173-174 and the other notes in the Technical Notes
section starting on page 177.

 These areas represent memory that's provided by your motherboard or by an
add-on memory board. Since it's not provided by EMS4 or EEMS memory, it
can't be mapped and can thus only be used by one program.

 These areas represent high memory that's not available for running
programs.

 These areas represent a single block of EMS4 or EEMS memory that's being
mapped into a like-sized block of conventional memory below 640K. Since
different blocks of EMS4 or EEMS memory can be mapped simultaneously into
the same block of conventional memory, different programs can be running
concurrently in the same conventional memory ~dash~ at least as far as your
PC'S processor is concerned.

 These areas represent blocks of EMS4 or EEMS memory that are available to
run additional programs ~dash~ or, for data storage, for use as a RAM disk,
print spooler, or disk cache, or for swapping graphics screens.

~Subhead~ Choosing the Optimization That Serves You Best

 The best way to optimize your system is by maximizing the "other" program
size for your particular hardware configuration, since there's little you
can do to affect the maximum "first" program size (see note 4 on page 177).
The easiest way to understand your options is to examine the tables on
these pages that apply to your particular PC. The table below summarizes
the way memory is allocated for different PC configurations. The tables on
the opposite page show in more detail the effects of different memory
configurations on the "first" and "other" sizes.

Table not shown.

~Subhead~ Table Legend

 The first four rows of each table list the hardware options that affect
optimization.  For the tables on the opposite page, the last two rows
indicate the resulting "maximum" program sizes for the given amount of
conventional memory. As Largest "Other" Program indicates, the smaller the
amount of conventional memory installed on your system, the greater the
maximum size of the "other" programs will be.

 These tables assume you've booted your system under MS-DOS 3.2, loaded an
exPANDed memory manager (or QEMM-386 on a PC), allocated 15 file buffers,
have DESQview "common" memory set to 17K, and have started up DESQview
using DV.COM (XDV).  These values will increase slightly if you run under
DOS 2.0 through 3.1. They'll decrease if you use DOS 4.x or higher, load
other device drivers or memory-resident programs (by the program's sizes)
or if you don't start up DESQview with DV.COM (by an amount that's highly
dependent on your hardware configuration ~dash~ see note 1 on page 177).

~Subhead~ Table Notes

 1  "Mono/Hercules" means a monochrome or Hercules display adapter, "CGA" a
color/graphics display adapter, and "EGA/VGA" an enhanced graphics or Video
Graphics Array display adapter.

 2  "PC/XT" means a PC or PC-XT.  "AT/386" means a PC-AT or 386 PC.

 3  "Conventional Memory" is the amount of memory installed in the 0K-640K
area ~dash~ excluding memory supplied by an EMS4 or EEMS board.  On a 386
PC, you always get the 0K values, because all 640K can be mapped. 0K isn't
possible on most other PCs.

 4  Since exPANDed memory on a PC-AT or 386 PC can be used as exTENDed
memory, there's no reason to have this configuration on these machines
~dash~ since you'll always get better "first" and "other" program sizes if
you allocate part of your exPANDed memory as exTENDed memory.

 5  DESQview uses 60K of exTENDed memory to load and run part of itself
~dash~ so, you must have at least 64K of exTENDed memory installed (see
page 134).

~Heading~ The Memory Status Program

 This appendix has discussed the concept of "first" and "other" program
sizes and how they apply to running programs on systems with particular
hardware and memory configurations. The Memory Status program

~Begin footnote~

The Memory Status program is included on your DESQview diskette.  You will
find it on the Open Window menu.

~End footnote~

lets you see the actual "first" and "other" sizes (and other memory
allocation information) for your system ~dash~ because Memory Status
dynamically displays the current memory usage of your running system at any
given moment.

When you run Memory Status, the following window appears:

The rows list the three memory areas of interest:

~Item~ Common Memory refers to the amount of memory in DESQview's Common
Memory Buffer (see Appendix A). The values it shows are in bytes, not K.
Generally, you can ignore these values. If Largest Available drops below
1,000 bytes, you might want to allocate more "common memory" by running the
Setup program and add another 2K to the table.

~Item~ Conventional Memory refers to the memory available to you for
running programs in the 0K-640K memory area of a PC. It consists of
motherboard memory, add-on memory, and exPANDed memory used to fill out
your system to 640K. On PCs with EMS4 or EEMS memory and 386 PCs with
QEMM-386, this may include areas of memory above 640K that DESQview uses to
run programs.

 Expanded Memory refers to the memory supplied by exPANDed memory boards.
It excludes exPANDed memory used to fill out the 0K-640K area and exPANDed
memory that was allocated to RAM disks, print spoolers or disk caches when
you booted your system or before you started up DESQview.

The columns list the current sizes of each of these memory areas:

~Item~ Total Memory is the total memory available on your system for the
given memory category. This value is fixed at the time you start DESQview
and depends on your hardware and memory configuration and on the device
drivers, memory-resident programs, and disk buffers you loaded when you
booted your system or before you started DESQview.

~Item~ Total Available is the total memory available at the current moment
in the given memory category. This may consist of pieces of fragmented
memory and thus doesn't necessarily reflect the contiguous memory needed to
run a program.

~Item~ Largest Available is the largest area of contiguous memory available
for a program at the current moment . You must subtract the 9K7 DESQview
overhead from the Conventional Memory and Expanded Memory values.

The most important numbers are:

~Item~ Largest Available Conventional Memory (middle right),  which gives
the size of the largest program that can be loaded at the current moment
without swapping other programs or running the program in EMS4 or EEMS
memory (also know as the "first program" size ~dash~ when Memory Status is
run all by itself).

~Item~ Largest Available Expanded Memory (bottom right), which gives the
size of the largest amount of exPANDed memory below 640K a  program that
can be run in  at the current moment. This number will always be 0K if you
don't have exPANDed memory, or if you have not backfilled conventional
memory with exPANDed memory, or if you only have an EMS3 board installed on
your system (even if it has an EMS4 driver).

Because these numbers tell you:

~Item~ The largest program (less about 9K7) that you can run at the current
moment without swapping a program to disk. This is the larger of Largest
Available Conventional Memory and Largest Available Expanded Memory.

~Item~ The maximum "other" program size for your system. When you start up
DESQview, the Largest Available Expanded Memory specifies this number, and
should correspond to the red size shown in the tables on pages 154-155
~dash~ less the 9K DESQview overhead and the space taken by device drivers
and memory-resident programs you loaded when you booted or before you
started DESQview. This number will always be 0K if you don't have EMS4 or
EEMS memory. It will also be 0K (zero) if you do not have any exPANDed
memory available below 640K.

The Memory Status program is small ~dash~ about 7K, including  DESQview
overhead. It runs in background and therefore dynamically reflects changes
in memory usage on your system as they occur.

This section only applies if you have an enhanced expanded memory (EEMS)
board or EMS4 board installed on a PC, PC-XT, or PC-AT.  It doesn't apply:

If you have a regular expanded memory (EMS3) board.  There are no steps
you can take to improve how DESQview uses EMS3 memory or to use EMS3 memory
to run programs.  This is a fundamental limitation of the EMS3 hardware
design. There are also no steps you can take to improve an EMS3 board which
has an EMS4 software driver; the extra steps described here refer to
hardware features not available for these boards.

 However, if you have a PC-AT, you should consider reconfiguringsome of
your EMS memory as exTENDed memory (see page)  ~dash~  because DESQview can
run part of itself inexTENDed memory.  Doing this reduces the amount of
conventional memoryDESQview uses by 60K, and thus increases the size of the
largest programyou can run by 60K.

 If you have less than 1MB of EMS4 or EEMS memory installed on your system.

 If you have a 386 PC.  All the optimizations described in this section are
done for you automatically.  You always get the "best" possible memory
configuration  ~dash~  if you have at least 1MB of 386 exTENDed memory and
have installed QEMM-386.

 The most important resources available to DESQview are the speed of your
computer and the amount and type of memory you have installed. The faster
your PC is, the more quickly DESQview (or any other program) can perform
its functions. But speed is not DESQview's most critical resource; memory
is. This appendix explains how knowing what kind of memory, how much of it
you have and how that memory is configured will allow you to get the
optimum performance from DESQview and the programs you run in DESQview.

~Subhead~ Expanded Memory: An Overview

 Most programs written for DOS 2.x to 4.x may access only the first 1024K
(one megabyte) of memory, and typically they only use the first 640K, since
the other memory areas between 640K and 1024K (called High Memory or
sometimes Reserved Memory or the Upper Memory Blocks) are reserved for
special functions. The maximum amount of memory that most programs and data
can occupy is 640K, less what DOS requires. This first 640K of memory is
called conventional memory. Without additional memory management, such as
loading device drivers into High Memory or using DESQview's ability to load
part of itself into memory above 640K, the largest single program you could
ever run inside DESQview would be about 430K ~dash~ because DOS takes
approximately 60K and DESQview uses about 150K. By using a memory manager
and loading part of DESQview into high memory, you can significantly
increase the amount of memory available to run programs.

If you run multiple programs on a computer with only 640K, 430K is the
maximum size of all the programs you can run concurrently, including all
their data. (The term concurrently means that multiple programs are both
loaded into the 0K-640K area of memory and are runing simultaneously in
this area.) This amount of memory can be very limiting for many of today's
DOS programs, so ways of reducing DOS and DESQview overhead are often used
in order to increase the size of memory available for each program. In
addition, DESQview, with additional memory, configured properly, can use as
much additional memory above 640K as you can add to your system.There are
differences, however, in how much and what kind of memory you can add to
different types of PC's and how DESQview can make use of that memory.

~Subhead~ ExTENDed Memory

 An 80286 or 386 or i486 PC can also have many megabytes of another type of
memory, called exTENDed memory. (You cannot install exTENDed memory on a PC
or PC-XT) ExTENDed memory begins at 1024K and continues from there; it is
NOT located between 640K and 1024K. A new classification of programs, using
a "DOS  Extender" can actually run in Extended memory and use some of the
lower 640K to handle their work with DOS. These programs are specially
written to be DOS Extended by the program's developer. Lotus 1-2-3 Release
3 is an example of one such program. Except for DOS Extended programs,
exTENDed memory is severely limited in utility by the fact that most
existing DOS programs can't use it, either to run themselves or to store
data. A memory manager, however, can turn exTENDed memory into exPANDed
memory, which DESQview can use.

DESQview can also run 64K of itself in the first 64K of exTENDed memory
(the High Memory Area or HMA). So, if you have an 80286 or 386 PC with
exTENDed memory installed, DESQview's overhead (in conventional memory)
drops by 64K to about 85K ~dash~ and the largest program you run
accordingly increases by 64K to 495K. DESQview was the first DOS program to
use the High Memory Area. Other programs have now also been modified to use
it as well. The  HMA may be used by only one program, so  it  should be
used by the program which fills it the most. DESQview uses practically all
of the HMA. Do not confuse high memory (the reserved memory between 640K
and 1024K) with the HMA (High Memory Area), which is another piece 64K of
memory starting at 1024.

~Subhead~ ExPANDed Memory

 In order to access more than 640K on all types of DOS computers (including
8088 and 8086), another type of memory was invented ~dash~ called exPANDed
memory (EMS). It is possible to both store data and run programs in
exPANDed memory, but only when the memory is configured properly and
managed effectively. DESQview can manage exPANDed memory for multiple
programs, even if those programs have not been modified to understand
exPANDed memory themselves. DESQview is the "control program" you need to
actually make use of all the capabilities of the EMS memory technology. EMS
stands for ExPANDed memory Specification.

~Subhead~ 386 or i486 PCs

 On a 80386 or i486 PC, you DO NOT need a special EMS memory board. All you
need is standard exTENDed memory, the Quarterdeck Expanded Memory Manager
386 (QEMM-386), and DESQview. QEMM-386 automatically converts a 386 or i486
PC's exTENDed memory into exPANDed memory. DESQview acts as the control
program to take advantage of the ability of the 386 PC's virtual 86 machine
architecture to emulate EMS4 memory. To DESQview and QEMM-386, both an
80386SX or i486 PC have the same memory management features as a 386 PC, so
all references to a 386 PC or an 80386 processor in this manual apply to an
80386SX or an i486 computer as well.

~Subhead~ Determining the Largest Program Size in DESQview

 The table below shows how DESQview allocates memory. With EMS or a 386 PC
DESQview can reduce its overhead substantially ~dash~ even to zero in some
cases ~dash~ by loading parts of itself in both exTENDed and EMS memory.
Your values may be slightly smaller or much larger depending on your use of
the LOADHI programs which come with Quarterdeck's QRAM and QEMM.
~Subhead~ About this Appendix

 Below is the table of contents for this appendix. Everyone should read the
first three sections. Pages 148-156, The Expanded Memory Technology is for
the more technically minded ~dash~ and can be skipped if you're not
interested in the details. Optimizing How DESQview Uses EMS4 or EEMS Memory
isn't mandatory reading either, but you may need to take some of the steps
described in that section to get the Largest Program Size listed above.

~Subhead~ Expanded Memory That DESQview Supports

 DESQview's power increases when you add an expanded memory board to your
PC, PC-XT, or PC-AT, or when you run DESQview on a 386 PC in conjunction
with Quarterdeck Expanded Memory Manager 3861
Begin footnote
Notes start at the end of this appendix
End footnote
. (QEMM-386). There are three standard types of exPANDed memory. DESQview
supports all of them:

~Item~ Expanded memory that follows the Lotus/Intel/Microsoft Expanded
Memory Specification Version 3. This is usually abbreviated as EMS memory,
EMS3 memory LIM memory, or sometimes LIM-EMS3 memory. EMS3 is a completely
compatible subset of EMS4.

~Item~ Expanded memory that follows the Lotus/Intel/Microsoft Expanded
Memory Specification Version 4. This is usually abbreviated as EMS memory,
EMS4 memory, LIM4 memory, or sometimes LIM-EMS4 memory.

~Item~ Expanded memory that follows the AST/Quadram/Ashton-Tate Enhanced
Expanded Memory Specification. This is usually abbreviated as EEMS memory
or sometimes enhanced-EMS memory.

Note that memory boards which were originally designed for EMS3 can have an
EMS4 driver written for them, but they will not gain all of the new
features of EMS4 because they lack the necessary hardware to perform the
advanced functions. The most important of these is the ability to map more
than 64K of memory at one time. EEMS memory boards can become EMS4 memory
boards by simply obtaining an EMS4 software driver from the manufacturer,
because the extra hardware necessary for the advanced functions is built
into EEMS boards. Almost all references to EMS4 in this manual apply to
EEMS as well.

The extra DESQview capabilities available to you are directly related to
the amount and type of exPANDed memory you have. DESQview uses each type to
its fullest potential and automatically detects its presence, as long as
you've loaded an exPANDed memory manager1~dagger~ (EMM) when you booted
your system.

~Subhead~ Expanded Memory NOT Supported By DESQview

 DESQview is not compatible with exPANDed memory emulators on 80286 PC's
which convert exTENDed memory or disk space into exPANDed memory without
additional hardware. These programs use significant amounts of memory below
640K and are not fast enough to perform effectively with DESQview.

~Subhead~ Determining If You Have Expanded Memory Compatible with DESQview

 You have exPANDed memory that's compatible with DESQview:

~Item~ On a PC, PC-XT, or PC-AT, only if you've purchased an exPANDed
memory board and installed it in your PC along with the corresponding
exPANDed memory manager driver program. Examples of these are:

 ~dash~  EMS Version 3 (EMS3) boards, such as the Intel AboveBoard,
BocaRAM, and Everex RAM 3000 and others which can use only 64K of exPANDed
memory at any one time.

 ~dash~  EMS Version 4 (EMS4) boards (which also include EMS3
compatibility) such as the Intel AboveBoard Plus, All Computers CHARGECARD,
Computer Peripherals CPI-XMA, Everex RAM 8000, Newer Technologies
Concentration, STB Rapidmeg, Teletek X-Bandit, DakotaRAM board, and any of
the EEMS boards with an EMS4 driver. These boards can access more than 64K
of exPANDed memory at any one time.

 ~dash~  Enhanced-EMS (EEMS) boards (which include EMS3 memory as a
subset), such as the AST RAMpage, AST SixPak Premium, AST Advantage
Premium, and PC Technologies RAMpartner.

~Item~ On a 386 PC,  if you have installed the Quarterdeck Expanded Memory
Manager 3861

~Begin footnote~

Notes start at the end of this appendix

~End footnote~

An exPANDed memory board is not the same as an exTENDed memory board. The
similarity of names makes this a confusing point. Unless your memory board
explicitly says that it's an exPANDed memory board that supports the EMS3,
EMS4 or EEMS standard (or you have a 386 PC and QEMM-386), you don't have
exPANDed memory. (See page 134 for information on using DESQview with
exTENDed memory.)

 If you have Quarterdeck's Manifest program, you can determine what kind of
memory you have, how it is configured and how DESQview and other programs
can use it.

~Heading~ How DESQview Uses Expanded Memory

 DESQview uses exPANDed memory in three ways:

~Item~ As a "swapping" area, to temporarily store programs when DESQview
needs additional space to load other programs or to save "graphics
screens."

~Item~ As data storage, for programs that explicitly know about and use EMS
memory for data ~dash~ such as 1-2-3 Release 2 or Release 3, WordPerfect 5,
Paradox, and so forth.

~Item~ As program memory ~dash~ that is, memory that programs can run in.

ExPANDed memory can also be used for RAM disks, print spoolers, and disk
caches. When used for these, load these driver programs before you start up
DESQview, so that all the programs you run can take advantage of their
features.

~Subhead~ Using Expanded Memory as a "Swapping" Area

 When all the programs you want to run at the same time won't fit in
memory, DESQview automatically manages memory for you by "swapping"
programs in and out as you need them. Although swapping can be done to a
hard disk, a RAM disk, or exPANDed memory, it's fastest when done to
exPANDed memory. Any type of exPANDed memory may be used for swapping.

When you start up a program, DESQview begins by finding a place in memory
for it to run. If there's an unused area large enough, DESQview puts the
program in that area.

Programs loaded in the first 640K can run concurrently, since they're
running in the memory that DOS knows about and supports. However, if
there's no unused area large enough for the program to fit in, one or more
of the programs already loaded are swapped out to make room ~dash~ which is
to say, they're removed from memory and stored somewhere else temporarily.

Programs that are swapped out are frozen (suspended) ~dash~ because those
programs are no longer in memory, where they must be for your PC to execute
them. When you switch back to a swapped out program, it's reloaded into
memory and resumes where it left off when it was swapped out.  (Programs
that can't be arbitrarily suspended must be designated as nonswappable in
your .DVP file.)

The amount of time it takes to swap one program out and another program in
is highly variable. If you're swapping to a hard disk, the time depends on
the size of your program and the speed of your hard disk. Hard disk times
vary enormously. A "fast" disk may swap three or even five times faster
than a "normal" disk. Swapping to a RAM disk is faster, but still not
optimal because, even though RAM disk is "memory," accessing it still
incurs DOS overhead. The fastest method is swapping to expanded memory.
It's virtually instantaneous.

~Subhead~ Using Expanded Memory as Data Storage

 Many programs ~dash~ such as 1-2-3 Release 2 ~dash~ use exPANDed memory to
make large amounts of data available quickly. When DESQview is used on a
system with exPANDed memory, it extends this capability by allowing several
programs to use exPANDed memory at the same time.  DESQview ensures that
each program's use of exPANDed memory doesn't interfere with any other
program's use of it.

For example, you could have 1-2-3 Release 2 and WordPerfect each storing
data in exPANDed memory while running in its own window. DESQview
automatically manages the allocations of exPANDed memory so that each
program "sees" only its own exPANDed memory.

~Subhead~ Using Expanded Memory as "Program" Memory

 Although swapping programs to exPANDed memory is nice, running programs in
exPANDed memory is even better. You can run programs in exPANDed memory
only if you have fully hardware compatible EMS4 memory, ENHANCED exPANDed
memory (EEMS), or are using a 386 PC in conjunction with QEMM-386.

Running programs in expanded memory means that you can run more programs
than would normally fit in 640K. You can run as many programs
simultaneously as will fit in your entire exPANDed memory, up to 32MB
worth. The size of each program is less than 640K (not counting the data a
program may store in exPANDed memory), and the total amount of memory used
for running programs can be many megabytes.

You cannot run programs in exPANDed memory if you only have EMS3 memory.
The reason is that with EMS3 your PC can only "see" one 64K piece of EMS
memory at any one time,  while with fully hardware compatible EMS4 memory,
or EEMS, it can "see" enough memory to run most existing DOS programs. You
only get capability to run programs in EMS4 memory when DESQview manages
your EMS4 memory.

~Subhead~ Optimizing The Use of the Memory You Have by Backfilling

 You may have to make sure the memory you have is available for optimal use
by DESQview by backfilling conventional memory with EMS. If you do not have
an 80386 PC, to properly use EMS4 memory, you may need to disconnect some
of your conventional memory (below 640K) and substitute EMS4 memory for it.
This is called backfilling conventional memory with exPANDed memory.
Although you may be reluctant to disconnect perfectly good memory, if you
don't, you severely limit the number and size of programs you can run in
EMS4 memory. In the worst case, you can't run any programs in EMS4 memory
~dash~ see Optimizing How DESQview Uses EMS4 or EEMS Memory on page 167.
Note that disconnecting conventional memory usually just involves changing
switch settings on your memory board and the documentation for the board
will usually explain how to do it. If not, contact your dealer or technical
support at your EMS board's manufacturer.

~Heading~ Installing Expanded Memory

 Each time you start up DESQview, it checks for the presence of exPANDed
memory and automatically uses it if it's available.  So, it doesn't matter
to DESQview whether you install DESQview first, exPANDed memory first, or
both at the same time.

~Subhead~ If You Have a PC, PC-XT, or PC-AT or PS2

 When you install an expanded memory board on a PC, PC-XT, or PC- AT, be
sure to follow the board manufacturer's instructions carefully.  You must
perform at least these four basic steps:

~Step~ Verify that the default factory switch settings are correct for your
hardware configuration and, if they're not, make them correct.

~Step~ Open up your PC chassis and install the board in an empty slot. We
recommend the board be populated with at least 2MB of memory.

~Step~ Install the exPANDed memory manager (EMM) for the board on your boot
disk and in your CONFIG.SYS file.

~Step~ Reboot your system to load this exPANDed memory manager.

Although it's sufficient to follow these steps, there are additional steps
we recommend depending on the type of exPANDed memory board you've
installed:

~Item~ EMS3 board.

 ~dash~  We recommend that you use part of your EMS3 board for swapping
programs and graphics screens. This occurs automatically unless you've run
the DESQview Setup program and specified an explicit SWAP drive to use (see
Appendix A).  Also, you can reduce DESQview's overhead if you have 64K of
exTENDed memory (see page 134) which may require you to change your EMS
board's settings if you don't already have exTENDed memory. There's no way
to improve how DESQview uses EMS3 memory or to use EMS memory to run
programs. This is a fundamental limitation of the EMS3 hardware design even
if an EMS4 software driver is in place.

~Item~ EMS4 or EEMS board.

 ~dash~  We strongly recommend that you optimize the use of EMS4 or
enhanced exPANDed memory by disabling part of your conventional memory and
backfilling it with EMS4 memory. If you do, DESQview and QRAM, if you are
using it, will automatically make optimal use of the memory your hardware
makes available.

~Subhead~ If you Have a 386, 386SX, or i486 PC

 If you have an 80386, 386SX, or i486 PC (they're all the same to DESQview
and QEMM-386, as far as memory management is concerned) there's no need to
install a special exPANDed memory board because, on a 386 PC, standard 386
exTENDed memory can act like exPANDed memory. There are only three things
you must do:

~Step~ Install Quarterdeck Expanded Memory Manager 386 (QEMM-386) on your
hard disk and in your CONFIG.SYS file.

~Step~ Reboot your system to load this exPANDed memory manager.

~Step~  Use as much of the unused area between 640K and 1024K as possible.

 ~dash~  Installing DESQview, QEMM-386 and running OPTIMIZE will usually do
this for you automatically.

~Subhead~ Verifying That Expanded Memory is Correctly Installed

 Once you've installed your exPANDed memory board (except on a 386 PC),
installed the exPANDed memory manager, and rebooted your system, it's
useful to be able to determine whether you've installed everything
correctly:

~Item~ When you reboot, watch the screen for information about exPANDed
memory ~dash~ generally in the form of a count-up as expanded memory is
tested. If no exPANDed memory information appears, something is wrong.
Recheck your hardware for the proper configuration.

~Item~ If you're familiar with DESQview, run the Memory Status program (see
page 175). If a nonzero number appears under Total Expanded Memory (bottom
left number), DESQview has recognized that you have exPANDed memory
installed. If the number is zero, you've done something wrong.

 Once your hardware is properly set up, you can also control DESQview and
your programs use that memory by using the Change A Program Menu, DESQview
Setup and the Tune Performance menu, as explained in appropriate sections
of this manual.

~Heading~ The Expanded Memory Technology

 This section offers a brief discussion, for the more technically minded,
of how exPANDed memory works and of how DESQview takes advantage of the
EMS4 memory technology to run multiple, large programs concurrently.

~Subhead~ PC Memory:  an Overview

 Three types of memory can be present on a PC: The following diagrams
illustrate the basic configurations of memory that are possible.

These areas represent conventional memory ~dash~ the memory between 0K and
1024K (1MB). The first 640K is used to run programs, and the remaining 384K
is reserved for the system.

 These areas represent exTENDed memory ~dash~ the memory starting at 1MB
and continuing to the end of the available address range. ExTENDed memory
extends the 1MB of conventional memory. Most 286 and 386 PCs with 1 MB of
memory have 640K of Conventional memory and 384K of exTENDed memory; they
do NOT have memory between 640K and 1024K.   ExTENDed memory can only be
used for RAM disks, print spoolers, and disk caches, or DOS extended
programs ~dash~ with one exception: DESQview can run 64K of itself in
exTENDed memory (see page 134).

 These areas represent exPANDed memory ~dash~ a special kind of extra
memory.  On a PC, PC-XT, or PC-AT, expanded memory and exTENDed memory are
physically different entities ~dash~ each requiring its own, special
hardware memory board.

~Begin footnote~

Although exPANDed memory boards can be configured to use part of their
memory as exTENDed memory, exTENDed memory boards cannot be used as
exPANDed memory ~dash~ except on a 386 PC.

~End footnote~

Expanded memory is a separate block of memory that sits beside
conventional and exTENDed memory. On a 386 PC, however, exTENDed memory can
act like exPANDed memory ~dash~ by loading Quarterdeck Expanded Memory
Manager 386 (QEMM-386) when you boot your system.

~Subhead~ How Conventional Memory Works

 Conventional memory is memory between 0K and 1024K (1MB).  It's the area
of memory in which all programs must run ~dash~ because DOS 2.x/4.x only
recognizes and supports programs loaded into this area. Conventional memory
is divided into three areas:

~Item~ Motherboard memory is the basic memory that comes with every PC.
It's called "motherboard memory" because it's located on your computer's
basic system board ~dash~ the "motherboard." It varies from 64K to 640K,
depending on your PC.

~Item~ Add-on memory is used to extend the motherboard memory when it's
less than 640K. For example, if there's 256K on your motherboard, you could
"add on" up to 384K of additional memory.  It's also called "add-on" memory
because you must "add on" a physical memory board that contains this
memory.

~Item~ High memory is the memory between 640K and 1024K (1MB). It's
sometimes called "reserved memory" because it's reserved for use by the
system ~dash~ for the ROM BIOS and hardware devices, such as display
adapter boards, network boards, and hard disk controllers. Unused addresses
in this region have no physical memory in them.

The motherboard and add-on memories must form one contiguous block,
starting at 0K and extending to a maximum of 640K. High memory, however, is
usually a collection of disjoint areas ~dash~ depending on your hardware
configuration.

The following diagram illustrates how conventional memory is divided up.
The use of the first 640K is the same for all PCs. The allocation of memory
in high memory, however, varies according to whether you have a PC, PC-XT,
PC-AT or 386 PC (see diagrams on the following page). The address values
are in hexadecimal on one side of the chart, and in decimal on the other.

~Subhead~ How High Memory is Allocated

 High memory has three main uses:

~Item~ As the area for the ROM BIOS ~dash~ that part of DOS that's built
into every PC and manages the hardware basics, such as reading the
keyboard, driving the printer, and displaying information on the screen.

~Item~ As the video display RAM, which stores the information that appears
on the video display monitor.

~Item~ As the area for hardware-specific ROMs ~dash~ for example, the ROM
for the enhanced graphics (EGA) display adapter and the hard disk
controller.

The next diagram illustrate how high memory is usually configured. The Page
Frame is the 64K area where most programs can "see" exPANDed memory. Unused
areas are used by DESQview to run programs and parts of itself; the DV.COM2
program places parts of DESQview into these unused areas. These areas may
also be used by the LOADHI feature of QRAM and QEMM.

~Subhead~ How ExTENDed Memory works

 ExTENDed memory is simply more memory starting at 1024K (1MB).  It's only
available on 286 and 386 PCs. It may only be used when the PC is in
"protected mode." DOS cannot function in "protected mode."

Unlike conventional memory, exTENDed memory has an important limitation:
exTENDed memory cannot be used for running standard DOS programs under DOS
2.x/4.x. It can only be used for RAM disks, print spoolers, and disk
caches, or DOS extended programs ~dash~ with one exception:  Some special
programs, like DESQview, can run 64K of themselves in exTENDed memory (see
page 134).

~Subhead~ How Expanded (EMS) Memory Works

 It's not necessary to understand how exPANDed memory works to use it,
since DESQview handles all the details for you automatically.  There are,
however, "right" and "not so right" ways to use it. So, a basic
understanding of the concepts and processes involved can help you be sure
that you're getting the most out of your expanded memory board.

There are three types of exPANDed memory. Conceptually, they work the same.
The difference is in their limitations, which are imposed by the hardware
design (see explanations of EMS3 and EMS4/EEMS earlier in this appendix).

The fundamental concept to understand about exPANDed memory is that DOS
doesn't know it exists.  As far as DOS is concerned, there's only 1MB of
memory addresses, 0K to 1024K, but DOS does not know whether any memory is
in all of these addresses.

~Subhead~ EMS3 Only Maps 64K At A Time

 Any 64K piece of exPANDed memory can be "mapped" into an unused 64K area
of high memory. The key concept is mapping. What it means is that there's
hardware on the exPANDed memory board that "fools" the PC into thinking
that a portion from the exPANDed memory board is really in an unused area
of conventional memory. The previously unused area now has memory in it.
The piece of memory at this location can be changed to some other piece
without losing the original data.

With exPANDed memory, if your program tells the exPANDed memory board to
"map" some 64K chunk of exPANDed memory into the 64K area of high memory
that starts at 784K then, when the program reads or stores data in the 784K
to 848K area, it would, instead, actually be reading or storing in a 64K
chunk of exPANDed memory ~dash~ as the following diagram illustrates:

Effectively, the mapped 64K area of high memory is a porthole onto a larger
area of exPANDed memory. It's just that, when you look through the porthole
you can only "see" things that are exactly that size and you can only see
one "view" at a time. If you want to see a different "view" through the
porthole, you have to tell the window to "shift views" Then, you see only
the new view you selected.

A program that's been modified to know about exPANDed memory can access
megabytes of data by looking at it in 64K chunks. The program might start
by telling the exPANDed memory manager (the program that controls the
"view") that it wants to use (view) a particular 64K area of exPANDed
memory. Then it fills this area with data. When this 64K area is full, it
then tells the exPANDed memory manager that it wants to use another 64K
area. Note that no information is moved. All the program's data is really
stored in exPANDed memory and available at normal memory speeds. It's just
that only one 64K area can be accessed at a time.

~Subhead~ How EMS4 and   Enhanced Expanded Memory (EEMS) Can Map More
Memory

 The deficiency of EMS3 memory is that most programs are larger than 64K
and thus can't run in exPANDed memory (since 64K is the maximum area "seen"
at one time). They can only use it for data storage. Two methods have been
developed to remove this restriction. The first was the
AST/Quardram/Ashton-Tate Enhanced Expanded Memory Specification (EEMS
memory or enhanced-EMS memory).  The second was EMS Version 4. Both EEMS
and EMS4 are supersets of EMS memory. The major difference between EEMS and
EMS4 is how the software driver is accessed. DESQview can determine the
correct method automatically. Each of these newer specifications can:

~Item~ Map an area larger than 64K (in fact any area from 16K to 1MB in
size).  This increases the amount of exPANDed memory which can be "seen" at
one time.

~Item~ Map several non-adjacent areas. (An EMS3 board can only map to a
single 64K area of high  memory.)

~Item~ Map areas of memory below 640K as well as above 640K. This is where
programs run, so if enough exPANDed memory can be mapped below 640K a
program can actually be run from exPANDed memory.

Taken together, these "enhanced" exPANDed memory capabilities make it
possible to run not just one, but multiple programs concurrently in
exPANDed memory. The process of multitasking is now viable because
context-switching (the process of allocating these time slices) can be done
by simply changing the piece of expanded memory which is "seen" below 640K.
DESQview conceals all the EMS4 mechanisms from the program and makes it
appear (to the program) that it's running by itself in the PC's
conventional (0K-640K) memory area.

~Heading~ Technical Notes

 The notes in this section provide additional technical information about
using an EMS4 or EEMS board with DESQview. Notes 1-6 are referenced by the
text of this appendix. Notes 7-10 are not referenced in the text, but provide
technical information not directly addressed elsewhere.

 1      If you use a 386 expanded memory manager other than QEMM-386 (such as
the Compaq Expanded Memory Manager), you may not be able to take advantage of
all of DESQview's 386 PC capabilities.

 2     All program sizes used in this appendix assume that you start up
DESQview by invoking DV.COM (which is a copy of XDV.COM) rather than DV.EXE.
When you start up DESQview using DV.COM, part of DESQview is loaded into
exPANDed memory areas between 640K and 1024K in addition to the page frame,
thus increasing the amount of conventional memory available to run programs.
For more information on DV.COM, see Installation Notes.

 DV.COM won't work if exPANDed memory mapped between 640K and 1024K conflicts
with some other device such as some types of local area network boards, or if
the first 64K of exTENDed memory (the HMA) can't be accessed properly with
some PC- compatibles. (This is the reason both DV.COM and DV.EXE are
provided.) If DV.COM doesn't work on your system, you should try to isolate
the reason. If you cannot get it to work, then delete DV.COM (a copy of it is
saved as XDV.COM).

 3     The memory sizes marked with a 3 in this appendix are computed for the
following configuration:

 Hardware. An IBM PC, IBM PC-XT, IBM PC-AT, IBM Personal System/2, Compaq
Deskpro 386, 100% IBM PC-compatible, or Deskpro 386 compatible with an
enhanced graphics (EGA) or Video Graphics Array (VGA) display adapter, add-on
memory removed or set to 0K, motherboard memory reduced to 256K, and an EMS4
or EEMS memory board with a minimum of 1MB (see note 5).

 Software. Booted under MS-DOS 3.3, an exPANDed memory manager loaded, 15
file buffers allocated (in CONFIG.SYS), DESQview "common memory" set to 17K
(see Appendix A), DESQview started using DV.COM (see note 2), and no other
device drivers or memory- resident programs loaded when you booted your
system or before you started up DESQview.

 DESQview also requires about 9K overhead per program, which has already been
subtracted out of all memory sizes used in this appendix (see note 7).

 See the tables on page 173-174 for more detailed information for your
particular hardware configuration.

 The memory limits used in this appendix refer only to the amount of memory
used by the program itself. If you're running a program ~dash~ such as
1-2-3 Release 2, Symphony, Framework II, or Paradox ~dash~ that uses exPANDed
memory to store data, these programs still have full use of the exPANDed
memory for data storage.

 4     The primary way to improve the "first" program size is to delete all
memory-resident programs (like Sidekick) from your AUTOEXEC.BAT file ~dash~
in fact, we recommend running such programs in DESQview windows anyway (see
Appendix E). You might also check that you aren't loading any unnecessary
device drivers in CONFIG.SYS. We recommend against reducing the number of
file handles (FILES in CONFIG.SYS) below 15, if you can. You can also use the
LOADHI program which comes with QEMM or QRAM to move items loaded below 640K
into the 640K to 1024K region. Loading a lot of items into this area may
force some of DESQview to reside below 640K.

 5     Maximum program sizes are ultimately limited by the total amount of
memory installed on your system ~dash~ that is, by the sum of your
motherboard memory, your add-on memory, and your EMS4 or EEMS memory.

 For example, if you have 128K of motherboard memory, 128K of add-on memory,
and 2,048K of EMS4 memory, your total memory is 2,304K.  Thus, the total of
all programs loaded and running concurrently cannot exceed 2,304K ~dash~ less
any memory you've set aside for RAM disks, print spoolers, disk caches. If
you load more than 2,304K of programs, the remainder is swapped out to disk.

 The maximum amount of memory that DESQview can use for running programs is
limited only by the amount of EMS4 memory that can be installed on your
system ~dash~ generally, 32MB on a PC, PC-XT, or PC-AT and 64MB or more (with
QEMM-386) on a 386 PC.

 6     Some add-on memory boards (such as the AST SixPakPlus) permit you to
disconnect all their memory by setting the switches to 0K. Most boards,
however, don't allow a 0K setting. If your memory board doesn't allow 0K, you
must remove it. If your memory board does allow a 0K setting, and has a clock
or communications port, you may want to leave it installed so you can
continue to use these features.

 7     DESQview requires about 9K overhead per program (for most programs),
which has already been subtracted from the "first" and "other" program sizes
listed in this appendix. However, the 9K DESQview overhead has not been
subtracted out of the sizes listed by the Memory Status program. So, the
Total Available Conventional Memory and Largest Available Conventional Memory
sizes will always be about 9K larger than the largest program you can run.

 When you use the Change a Program menu (see Chapter 7) to change a program's
size, the number you enter for Memory Size (in K) should not include
DESQview's overhead. So, when specifying a minimum memory size, always
subtract 9K from numbers given by the Memory Status program before you enter
that number in the Memory Size (in K) field. (To run very large programs you
should enter a maximum program memory size, see page 121.)

 The overhead per program isn't always exactly 9K. For program script buffers
above 1K, add the size over 1K. If your program uses EGA or VGA text modes
that display more than 25 lines, add in the numbers in the table on page 123,
less 4K (which is already included in the standard 9K value). For programs
that have the Displays graphics information option set to ON, add 12K (for a
total of 21K) if you have a CGA and you don't have any exPANDed memory. Also,
most programs that come with DESQview ~dash~ DOS Services, Add a Program,
Change a Program, and DESQview Companions ~dash~ require additional overhead
varying from 1K-10K.

 8     If you have a Hercules, enhanced graphics (EGA) or Video Graphics
Array (VGA) display adapter, and run graphics programs that use EGA modes,
DESQview tries to use exPANDed memory to retain the contents of the screen
when you switch away to another program. It uses exPANDed memory because an
EGA or VGA can have 64K, 128K, or 256K or more of data displayed on the
screen ~dash~ an amount of information that can be saved quickly only by
being moved to exPANDed memory. (If you don't have exPANDed memory, or not
enough is available, "graphics screens" are saved on disk.)

 9     When you run a communications program that you want to work in
background, turn OFF its Can be swapped out of memory option (see page 120)
and  load it first if you want it to do high-speed communications  ~dash~
except on a 386 PC.If you have any other nonswappable programs, load them
immediately after your communications program so as not to fragment memory.

 10      Expanded memory is allocated on a request basis. When a program that
supports exPANDed memory requests exPANDed memory, that memory is removed
from the total pool of available exPANDed memory and is thus not available to
run programs ~dash~ until the program releases it back to the pool or the
window is closed.

 11      Alternate Maps is a feature of EMS4 which DESQview will use if they
are available. An "alternate map" is a method of remembering the way exPANDed
memory is configured for a particular program. When "remembered" in an
alternate map, a particular memory configuration can be reset very quickly;
much faster than re-mapping many individual pages. If there is only one
alternate map (in addition to the mapping hardware required for normal EMS
operations, DESQview sets the alternate map to remember the original memory
set-up when DESQview was started.  If there is more than one alternate map,
then DESQview uses one for itself and then allocates one alternate map per
program. Thus the first windows opened will each be able to be brought back
into memory as quickly as possible. When the alternate maps are exhausted,
DESQview must resort to mapping individual pages for those programs.

 Alternate maps are an optimal feature of EMS4. DESQview will use them
automatically if they are present. To find out if your exPANDed memory
manager supports this feature you can use Quarterdeck's Manifest.  Manifest
lists Alternate Maps under "Expanded" ~dash~ and you must run manifest
outside DESQview to determine whether or not your memory board supports this
feature.