New Star Software Collection/NSS_Collection.iso/3-069 qemm 603/1.ima/QEMM-MAN/CH8.QEM

Text File | 1991-10-07 | 10.0 KB | 226 lines

Chapter 8

Other QEMM-386 Programs

This chapter describes two other QEMM programs, EMS2EXT and EMS,
which give additional control over expanded memory. These two
programs can be used separately or they can be used together to
give you some dynamic control over your extended memory
allocation.

If your system has EMS 4.0 expanded memory, but not extended
memory, you may want to use the EMS2EXT.SYS device driver
supplied with QEMM. EMS2EXT can supply expanded memory as
extended memory to programs that access extended memory in a
certain prescribed manner. Two such programs are IBM's
DisplayWrite and the VDISK.SYS RAM disk utility supplied with
DOS. Many disk cache utilities often use extended memory in this
way also.

~Subhead~ EMS2EXT.SYS

These and other programs can be used with EMS2EXT.SYS because
they do not require that extended memory (memory above 1024K) be
physically present, nor do they need to directly address this
memory. They make demands upon this memory in a logical as
opposed to a physical sense. And they access the contents of this
memory through requests of a memory manager, which makes this
memory available to the program. Programs which make use of
extended memory in this way provide a performance boost over
programs that rely on disk storage alone, since the in-memory
transfer is much faster.

Programs that expect extended memory to be physically present
cannot make use of EMS2EXT. Quarterdeck's QEXT.SYS driver, used
with DESQview, cannot use memory supplied by EMS2EXT.

Because this logical or virtual memory capability enhances a
programs performance, you should have little difficulty in
determining which of your applications support this memory. They
will surely mention it. And, if your complement of expanded
memory lends itself to this use, you will want to make this
memory available to these programs.

If you decide to use EMS2EXT you may also want to consider the
relative speed of the various types of memory you have in your
system. It is possible for there to be a significant speed
differential between these types of memory. EMS2EXT is capable of
determining this difference and can allocate either slow memory
or fast memory for use as extended memory.

EMS2EXT is a device driver and therefore needs to be loaded when
your system boots up. This requires a DEVICE= statement in your
CONFIG.SYS file. When you have determined the amount of memory to
ask EMS2EXT to manage as extended memory, you need to modify
CONFIG.SYS to load EMS2EXT. The statement to load EMS2EXT must
come after the one that loads your expanded memory manager and
looks like:

     DEVICE=C:\QEMM\EMS2EXT.SYS MEMORY=nnn speed

Several components of this statement need to be explained.

~Item~ The nnn parameter in MEMORY=nnn is the number of kilobytes
of expanded memory to allocate, i.e. MEMORY=512. This is
optional.

~Item~ The speed parameter is the optional specification for
using faster or slower memory for allocation. Leave this part of
the line blank or use either, FAST or SLOW.

~Subhead~ The EMS Programs

 The EMS programs provide a number of informative and powerful
functions to help you make the best use of your EMS 4.0 expanded
memory where you might have special or unusual requirements.
Although anyone might benefit from the EMS summary status report
and others by seeing the detail of expanded memory allocation,
other uses of EMS which will be described in these sections are
for the more technically minded.

Most of the functions of the two EMS programs, EMS.SYS and
EMS.COM, involve the manipulation of expanded memory handles. An
EMS handle is a reference to a block of memory (zero or more EMS
pages) that the expanded memory manager issues when it allocates
memory. A handle is represented by a number and it may be given a
name.

An expanded memory handle, its name, and the pages of memory
associated with the handle are the fundamental tokens of
interaction between an application program and an expanded memory
manager. The two EMS programs give you some of the same control
functions available to programs. The principal need for caution
when using the EMS programs arises because they give you access
to handles which may belong to other programs and EMS will not
prevent you from inadvertent mischief making.

With the EMS programs you can allocate and name a block of memory
with the CREATE option, and specify that the memory be fast or
slow memory.  You can free expanded memory pages allocated to a
handle with the FREE option. You can read data from a file into
allocated expanded memory or write the data from allocated
expanded memory to a file with the LOAD or SAVE options. An EMS
handle can be renamed, and the number of memory pages can be
changed.

Along with the report features of EMS you can experiment with the
functions using EMS as a command line interface to the expanded
memory manager.

 If parts of the expanded memory in your system runs at different
speeds, you can use EMS to pre-allocate memory of one speed
before you load a device driver or TSR so that it can only use
the memory that remains at the other speed; and you can then free
the memory for use by your other applications. Quarterdeck
Manifest can show you if your memory runs at different rates.

Developers using expanded memory may make use of the LOAD and
SAVE function to help them when they need to work with the same
context repeatedly during development and debugging.

All of these uses of EMS require an extensive knowledge of the
various aspects of your system, from the details involved in the
DOS boot sequence, to uses and capabilites of expanded and
extended memory as well as an understanding of the applications
you are attempting to control and optimize.

Both EMS.SYS and EMS.COM respond to the same command line
options. You use EMS.SYS from within the CONFIG.SYS file to
manipulate expanded memory during the system boot sequence. You
use EMS.COM from within the AUTOEXEC.BAT file at the end of the
boot sequence or directly from DOS prompt as needed.

Described below are the command line options of EMS and the
parameters required by each option. Some of the options have an
abbreviated form.  Where this is the case, the alternate form is
shown immediately following the option when it is first
introduced, and is enclosed in parentheses.

To get a summary report of your expanded memory, you issue the
EMS command from the command line without any option specified.
EMS outputs the following information:

~Item~ the total amount of expanded memory, and

~Item~ the amount currently available, and

~Item~ the address of the Page Frame.

The DIR option displays, in tabular form, a breakdown of the
current expanded memory allocated. For each allocated handle, the
number of expanded memory pages is given, the number of kilobytes
of memory those pages represent, and the name assigned to that
handle, if any.

The CREATE (CR) option is used to allocate pages of expanded
memory. It takes two parameters. CREATE requires that you provide
a name for the memory you are allocating and that you specify the
amount of memory. The name may be one to eight characters long.
The name need not be enclosed in quotation marks unless it
contains blanks. The amount of memory you are allocating may be
expressed in EMS pages (16K per page) or in kilobytes. If you
specify the number of kilobytes, the memory manager will round
the number up if necessary to determine the number of pages.
Follow the EMS CREATE command with EMS DIR command to confirm the
allocation and to determine the handle number assigned to the
name.

The CREATEFAST (CFAST) and CREATESLOW (CSLOW) options are forms
of the CREATE option that also instruct the memory manager to
allocate the memory from either faster or slower memory. Use
Manifest's Expanded Memory Timings to determine if this form of
CREATE is important to you.

The FREE option frees memory and deallocates a handle. FREE
requires that you specify the handle to deallocate~dash~by its
name or its number.

The RENAME (REN) option lets you assign a new name to a handle.
The first parameter to RENAME is the original handle. You may
refer to this handle by its number or its name. The second
argument is the new handle name.

The RESIZE (RES) option lets you increase or decrease the number
of pages assigned to a handle. Its two arguments are the same as
those of CREATE.

The SAVE option allows you to save the contents of the expanded
memory pages associated with an EMS handle to a file. This option
requires that you also specify the handle name (or number) and
the file name.

The LOAD option allows you to restore the contents of expanded
memory pages that have been stored in a file. This option
requires that you also specify the handle name (or number) and
the file name which contains the data you want to restore. The
number of pages required will be automatically allocated based on
the files size.

The EMS programs also respond to the options common to all the
programs supplied with your QEMM-386 programs:

~Item~ NOPAUSEONERROR (NOPE) instructs EMS not to pause on error.

~Item~ PAUSE instructs the program to pause while parsing
commands.

~Item~ HELP displays EMS help text.

~Item~ ? lists all EMS command parameters.

~Subhead~ Using EMS with EMS2EXT

You can load EMS2EXT as described in the EMS2EXT section of this
chapter, but without specifying any memory parameter at all.
EMS2EXT will be resident, but it will not allocate any memory. It
will, however, recognize as its memory a handle with the name
"EMS2EXT". You can then, as needed, create, grow, or shrink the
amount of extended memory for this handle using EMS.COM.

This capability should only be used in special situations when
you know how and when the program will use extended memory. For
instance, a program could be given extended memory only while it
is running. You could make a batch file which ran EMS CREATE
"EMS2EXT" 128K before running the application. When the program
terminates, another EMS statement could free the memory.