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STACKER NOTE Stac Electronics Technical Note
Subject: Performance differences between Stacker software and
coprocessor versions.
Tech010- 2/20/92
Page 1 OF 1
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STACKER's software version is supplemented and enhanced by the
coprocessor card. The STACKER coprocessor card yields the highest
compression of data, the smallest device driver and the fastest I/O.
Note: For a coprocessor install checklist, see tech008.
Q: What types of performance increases will I see with the
coprocessor ?
A: 1. Hardware compression offers as much as 10-20% more disk
space;
2. Disk reads and writes are 5-15% faster;
3. The higher performance is especially apparent on slower
machines.
4. The device driver memory requirements with the card are
as little as 14k vs. 26k for the software version.
Q: What is the difference between the XT/8 coprocessor and the
AT/16 ?
A: 1. The AT/16 is a 16 bit card designed for At class
machines such as 286, 386 and 486s. The XT/8 is an 8 bit card
designed for XT class machines.
2. The AT/16 uses an I/O address whereas the XT/8 requires a 16 K
upper memory address. Note: on 386/486 machines, the XT/8
requires its 16K upper memory range to be excluded from use
by memory managers. Neither card requires an IRQ.
3. Both coprocessors incorporate the same compression chip so
they will achieve the same amount of compression.
Q: What if some hardware conflict prevents the coprocessor from
functioning ?
A: If the coprocessor card does not install correctly or load at
boot time, STACKER will still run ("Coprocessor card not
functioning--invoking software driver") and data will still be
both compressed and accessible. You would just be operating
without the benefits of the card.