Symantec Device Driver Degrades BABY/36 Performance

California Software (Santa Ana, Calif., new window) has claimed that Symantec's device driver SYMEVNT.386 can cause significant degradation to the performance of its BABY/36 product, a PC-based replication of the IBM System/36 designed to provide a Windows NT environment for RPG II applications.

According to Symantec's Web based Knowledge Base, some applications use the software interrupt INT 21 to chain between modules. The Symantec file SYMEVNT.386 also uses this software interrupt to monitor drive activity and other system events. SYMEVNT.386 hooks the front and back end of the software interrupt. Because SYMEVNT.386 hooks the back end of the interrupt, Windows 9x changes information the other application is counting on to be valid.

BABY/36 does in fact use INT 21 during SSP operations among other areas of the emulation platform. California Software’s internal testing has demonstrated as much as 10 to one degradation in Windows 98 while this driver is loaded.

A quick way to check to see if this driver is interfering with the operation of BABY/36 is to rename the driver and reboot. During the reboot Windows 9x will issue an error as it tries to load the driver. Ignore this and continue to boot the computer. Test to see if this has resolved any BABY/36 performance issues.

To permanently remove the driver without uninstalling the Symantec product you must edit the registry. Directions for doing this are located at the Symantec Web site, (new window), under "Manually Removing SYMEVNT from Windows 9x."

According to Symantec SYMEVNT.386 is used by versions 7.x, 8.x and 9.x of pcAnywhere for full screen DOS foxes, remote printing and drive security. SYMEVNT.386 is not used on Windows NT but is used by various Symantec products including pcAnywhere, Norton Antivirus and Norton Utilities.

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