Mac OS 7.6.1: 5400/6400 With L2 Cache Turned Off

A problem was found on Power Macintosh 5400 and 6400 computers with a Level 2 cache. This problem will also occur on Mac OS-compatible computers that have Level 2 cache and are based on the same logic boards as the 5400 and 6400.

After installation of Mac OS 7.6.1, the Level 2 cache is inadvertently turned off. This is an existing problem with Mac OS 7.6 in cases where the 54XX/64XX Update extension is installed.
This problem can also appear after installing Mac OS 7.6.1 Update or after installing 54xx/64xx Update 1.1. Apple is aware of the situation, and there is a solution. A software fix titled "54xx/64xx L2 Cache Reset" has been posted to Apple software update sites.

Use of the software fix requires a Power Macintosh or Performa 6360/54xx/64xx computer with either of the following installed:

- Mac OS 7.6.1 Update, or
- "54xx/64xx Update 1.1" with System Software 7.5.3 or later.

The "54xx/64xx L2 Cache Reset" software fix corrects a problem which disables the L2 cache feature on some Performa and Power Macintosh computers with a Level 2 cache. The fix also works on Mac OS-compatible computers whose logic boards are based on Apple's design. With the 54xx/64xx L2 Cache Reset" software fix, the affected computer's Level 2 cache is enabled and performance is improved.

The Tech Info Library article titled "54xx/64xx L2 Cache Reset: Read Me" offers more information on this software fix.
Published Date: Feb 18, 2012