__________________________________________________________________ STACKER NOTE Stac Electronics Technical Note Subject: Performance differences between Stacker software and coprocessor versions. Tech010- 2/20/92 Page 1 OF 1 __________________________________________________________________ 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. *Upgrading to the coprocessor version from software only:* Upgrading from the software to the coprocessor version does not require re-installing STACKER. However, only those files written to the drive with the coprocessor benefit from the higher compression. With version 2.0, the files can be recompressed using SDEFRAG with the /R parameter. Recompressing the files under version 1.x requires that the files be reloaded into the Stacker drive.