Category : Tutorials + Patches
Archive   : STAC0694.ZIP
Filename : 4517.TXT

 
Output of file : 4517.TXT contained in archive : STAC0694.ZIP
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STACKER NOTE STACKER NOTE
STACKER DRIVER SIZE IN MEMORY
(Applies to Stacker 4.0)
STAC FAX 4517 (05-24-1994)
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BACKGROUND

The Stacker device driver is a memory resident program. Your
system's configuration determines how much space the driver takes
in conventional memory (the first 640K RAM). The major factors
affecting the driver's size are whether your system can use DOS
Protected Mode Services (DPMS), and the size of the drive you are
compressing. Note that Stacker runs as a block device driver, and
is usually loaded into conventional memory. However, it is also
eligible to be loaded into the upper memory blocks just like any
other device driver. See StacFax 2101 for information on loading
Stacker high.

WHAT SIZE WILL THE STACKER DRIVER BE?

- Determine if your system can use DPMS
- Determine which cluster size your system will use
- Determine the approximate size of the Stacker driver
- Other factors affecting driver size

Determine if your system can use DPMS

Versions of DOS that support preloading compression drivers also
allow the use of DPMS. Generally, MS-DOS 6.x, Novell DOS 7, and
PC-DOS 6.x with file dates after 9-30-93 support preloading.
Using DPMS, a portion of the driver is loaded into a "protected"
area of Extended Memory. This significantly reduces Stacker's
driver size in conventional memory. In order to be sure that your
system is using DPMS, examine your CONFIG.SYS file. Look for the
line:

DEVICE=C:\STACKER\DPMS.EXE
If the line is present, Stacker is making use of DPMS. The line
will automatically be inserted for you during Setup if your DOS
version supports preloading.

Determine which cluster size your system will use

The size of the Stacker driver is affected by the cluster size it
uses during Setup. This in turn is determined by the size of the
drive you are compressing. As a rule of thumb you may expect the
following cluster sizes at the default compression ratio of
2.5:1: A physical drive less than 205MB will use 8K clusters. A
physical drive between 205MB and 419MB will use 16K clusters. A
physical drive over 420MB will use 32K clusters. These boundaries
are not exact and your system may vary. See StacFax 4505 for
details on cluster size. The Stacker driver uses more memory with
larger cluster sizes.

In order to determine which cluster size your system is using
type:

CHECK /D drive:
where drive: is the drive letter of your Stacker drive. Locate
the column "Stacker Drive x:". At the bottom of that column will
be a statistic "Bytes per Cluster". This is the cluster size your
system is using for that Stacker drive. If you have more than one
Stacker drive, the size of the Stacker device driver is
determined by the largest cluster size used.

Determine the approximate size of the Stacker driver

The Stacker driver uses conventional memory approximately as
follows:

8K Clusters 16K Clusters 32K Clusters
With DPMS 16K 24K 40K
Without DPMS 44K 53K 71K
One Kilobyte = 1024 bytes.

Other factors affecting driver size

These numbers are approximate because other factors also affect
the driver size. These include the number of drives you compress
and whether you turn on Automounting for a removable drive. The
driver will also be significantly larger (about 8.3K) if you are
not using DPMS and do not have the line DOS=HIGH in your
CONFIG.SYS file. Each Stacker drive you compress will add about
560 bytes to the Stacker driver. Automounting also adds about 560
bytes per drive. Also, DPMS itself uses about 2K of conventional
memory.
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Copyright 1994 Stac Electronics


  3 Responses to “Category : Tutorials + Patches
Archive   : STAC0694.ZIP
Filename : 4517.TXT

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

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