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DISCUSSION Mac OS 7.6 is not recommended for a 68030-based computer with a 68040 upgrade card installed. If Mac OS 7.6 is installed on a computer with this configuration, it will exhibit problems starting up. The performance improvements implemented in System 7.5 update 2.0 (7.5.3) specifically for 68030-based computers, can cause cache flushing problems on the 68040 upgrade card when Mac OS 7.6 is installed. There is no workaround to user Mac OS 7.6 with these upgrade cards installed. System 7.5.x users can startup in 24 bit mode with Virtual Memory turned off, turn off the cache of their 68040 cards, and still see benefit from their upgrade card. Although Apple has not done extensive testing, cards which only increased the speed of an existing processor should work. For example, a 33 MHz 68040 upgrade card in a 25 MHz 68040 computer, or a 33 MHz or 40 MHz 68030 upgrade card in Macintosh IIci class computers. These cards should work correctly with Mac OS 7.6. Power Macintosh Upgrade Card users cannot use LaserWriter driver 8.4 in 68040 mode. LaserWriter driver version 8.4, installed on PowerPC computers, will not work on computers with 68040 microprocessors. If you have a Power Macintosh Upgrade Card and switch between PowerPC and 68040 modes, you will not be able to print in 68040 mode unless you install LaserWriter driver version 8.3.4 instead of version 8.4. You can install this LaserWriter version by installing a universal system on your computer. (The universal system is a custom installation option.) This article was published in the 24 January 1997 "Information Alley." |
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| Document Information | |
| Product Area: | Mac OS System Software |
| Category: | Mac OS 7.6 |
| Sub Category: | General Topics |
| Keywords: | sys76, kalley, ktoptil |
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