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STACKER NOTE                          Stac Electronics Technical Note

Subject: STACKER 2.0 device driver memory requirements.

Tech024 - 2/20/92
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The STACKER device driver, STACKER.COM , requires a modest amount of
resident conventional memory.  The resident size of the Stacker device
driver depends on the Stacker product being used, and on the way
Stacker is configured.  During the initialization phase, as it is
loading and mounting the STACKER drives, it requires slightly more
memory than when resident.

Refer to the following tables to determine how much memory the Stacker
device driver requires.  These numbers should be used as guidelines.
Once Stacker is installed, observe the STACKER.COM display as the
system starts to see the exact amount of memory the driver is using.

STACKER 2.0
This table represents memory required for each Stacker product with a
single Stacker drive using 8k clusters.  It also shows the requirements
on a system where Stacker is using EMS memory.  When Stacker is
configured to use available EMS memory, it will use 64k of EMS for its
cache and buffers.

       Product                With EMS              Without EMS
                        (Resident/(Initial))   (Resident/(Initial))
     2.0 Software            26K/(40K)               41K/(47K)
  AT/16, MC/16, XT/8         14K/(40K)               30K/(41K)

Additional Stacker Drives:
If using more than one Stacker drive, the device driver will consume
slightly more memory to map each additional drive.

       Product                With EMS              Without EMS
         All                    1.2K                    3 K

4K vs. 8K Clusters:
A default cluster size of 8k offers better compression than 4k .
However, the device memory required to achieve the better compression
is slightly greater than the 4k option.  With 4k clusters, the base
driver size is reduced by the amount in the table below.

       Product                With EMS             Without EMS
     2.0 Software                4K                     8K
  AT/16, MC/16, XT/8                                    4K
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1992 STAC ELECTRONICS
