56 lines
2.4 KiB
Plaintext
56 lines
2.4 KiB
Plaintext
__________________________________________________________________
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STACKER NOTE Stac Electronics Technical Note
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Subject: Performance differences between Stacker software and
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coprocessor versions.
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Tech010- 2/20/92
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Page 1 OF 1
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__________________________________________________________________
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STACKER's software version is supplemented and enhanced by the
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coprocessor card. The STACKER coprocessor card yields the highest
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compression of data, the smallest device driver and the fastest I/O.
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Note: For a coprocessor install checklist, see tech008.
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Q: What types of performance increases will I see with the
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coprocessor ?
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A: 1. Hardware compression offers as much as 10-20% more disk
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space;
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2. Disk reads and writes are 5-15% faster;
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3. The higher performance is especially apparent on slower
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machines.
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4. The device driver memory requirements with the card are
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as little as 14k vs. 26k for the software version.
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Q: What is the difference between the XT/8 coprocessor and the
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AT/16 ?
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A: 1. The AT/16 is a 16 bit card designed for At class
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machines such as 286, 386 and 486s. The XT/8 is an 8 bit card
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designed for XT class machines.
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2. The AT/16 uses an I/O address whereas the XT/8 requires a 16 K
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upper memory address. Note: on 386/486 machines, the XT/8
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requires its 16K upper memory range to be excluded from use
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by memory managers. Neither card requires an IRQ.
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3. Both coprocessors incorporate the same compression chip so
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they will achieve the same amount of compression.
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Q: What if some hardware conflict prevents the coprocessor from
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functioning ?
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A: If the coprocessor card does not install correctly or load at
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boot time, STACKER will still run ("Coprocessor card not
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functioning--invoking software driver") and data will still be
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both compressed and accessible. You would just be operating
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without the benefits of the card.
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*Upgrading to the coprocessor version from software only:*
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Upgrading from the software to the coprocessor version does not
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require re-installing STACKER. However, only those files written
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to the drive with the coprocessor benefit from the higher
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compression. With version 2.0, the files can be recompressed
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using SDEFRAG with the /R parameter. Recompressing the files
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under version 1.x requires that the files be reloaded into the
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Stacker drive.
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