Black Box 4/BlackBox.cdr/textinfo/drtips.arj/1301.TXT

Text File | 1991-11-26 | 5.4 KB | 116 lines

Document 1301
Basic Memory Optimization

Initials:
        11/26/91
    DRDOS 6.0

Description:

 System Memory Optimization

Because the DR DOS 6.0 operating system has been designed to work
with all IBM-compatible personal computers and software applications,
there is no single perfect memory setup that will optimize
memory use for all situations. Memory optimization will depend both
on your particular hardware setup and the software applications you
will be using. However, with a bit of trial-and-error system fine
tuning, you can optimize DR DOS memory management to meet your particular
needs. Below are techniques and suggestions that will help you optimize
your computer/software setup.

Changing Order of Memory Allocation

The first step in optimizing your system memory can be as simple as
rearranging the order in which memory blocks are assigned by the config.sys
and autoexec.bat files.  The general rule here is to use upper memory
and high memory as much as possible to free conventional memory for
your applications. With this in mind, you should typically use HIBUFFERS
and relocate the DR DOS kernel code to high memory by using the /BDOS=FFFF
option of the DR DOS memory management drivers, HIDOS.SYS and EMM386.SYS.
Also, if you have any add-on cards that use RAM, make sure that they are
configured so that their RAM is allocated from the beginning or end
of upper memory.  For example, place a network card immediately above
the video RAM area instead of in the middle of upper memory.

Following this, device drivers and TSRs can be loaded into upper memory.
For best memory allocation, those drivers and TSRs that occupy the
largest blocks of memory should be loaded first and contiguously.
For example, if you need to load three device drivers and two TSR
programs, order them in descending order in your config.sys file,
beginning with the driver that will occupy the most RAM, to the driver
or TSR that will occupy the least RAM. The documentation for the drivers
and TSRs should indicate the amount of RAM they require; however,
if they do not, you can determine this yourself by using the following
procedure:
1. Load the driver or TSR.
2. Use the MEM /U or /B command to see a report of your
memory usage (see Chapter 10 of the DR DOS 6.0 User Guide for
a full description of the MEM command and Chapter 12 regarding loading
device drivers and TSRs).

Expanding Files

If, after determining the size of your drivers and TSRs and loading
them into high memory, a driver or program fails to run properly or
produces an out of memory error message, the problem might
be that the driver or program is expanding itself in RAM.

Some device drivers and TSR programs occupy a minimal amount of RAM
after they are loaded into memory, but, while initializing, might
actually expand and take up considerably more RAM than they will ultimately
need.
Another method of verifying the program's true RAM size is to load
it into conventional memory (i.e., by deactivating the HIDEVICE, HIINSTALL,
or HILOAD commands), activate the program, and then run the MEM /B
command to see the actual amount of RAM the program occupies. If the
program or driver is expanding itself in RAM, and you want
to load it into upper memory, you will have to allow sufficient upper
memory RAM to accommodate the initialization size of the program.
It might be necessary to use trial-and-error to determine this size.  See
also "Using MemoryMAX with NetWare" on page 33 for an example.

Example

In the following example, let's assume you want to load Device Drivers
1, 2, and 3, and TSR programs 1 and 2, each requiring the following
amounts of memory:

Driver #1       =  13Kbyte of RAM
Driver # 2      =  10Kbyte of RAM
Driver # 3      =  16Kbyte of RAM
TSR # 1 =  4Kbyte of RAM
TSR # 2 =  6Kbyte of RAM

Using the MemoryMAX HIDEVICE and/or HIINSTALL commands, enter these
lines into your config.sys file:

HIDEVICE = C:\DRIVER#3.SYS      ; which uses 16kb RAM
HIDEVICE = C:\DRIVER#1.SYS      ; which uses 13kb RAM
HIDEVICE = C:\DRIVER#2.SYS      ; which uses 10kb RAM
HIINSTALL = TSR#2               ; which uses 6kb RAM
HIINSTALL = TSR#1               ; which uses 4kb RAM

Note:
There can be exceptions to loading TSRs and drivers in
the "largest first" system described previously. Some device
drivers must be loaded in a specific order. Read the manufacturer's
documentation carefully before installing any driver.

Note that in the above example, you can load the two TSRs with the
HILOAD command placed in the autoexec.bat file. For a discussion
of the MemoryMAX HIINSTALL, HIDEVICE, and HILOAD commands, see "MemoryMAX
System Commands and Drivers" on page 4 in the DR DOS 6.0 User Guide.

LIM Page Frame

Some applications run better with the availability of LIM memory (sometimes
called EMS, or expanded memory). The documentation for each of your
applications will indicate if LIM memory is required.

If the application does not require LIM memory, be sure that no LIM
page frame is defined. This will save 64 Kbytes of upper memory. In
the EMM386.SYS line of your config.sys file, disable the page frame
with the switch /F=NONE. If using HIDOS.SYS on a machine with a LIM
4.0 memory card, you can disable the page frame by specifying /CHIPSET=EMSALL.