Apple’s Level 2 Cache Fix — Last week, Apple released the 54xx/64xx L2 Cache Reset extension, fixing a bug that disabled the Level 2 processor cache in machines using Apple’s "Alchemy" motherboard design. This includes Power Macintosh or Performa 6360, 5400-series, and 6400-series computers, Power Computing’s PowerBase series, and UMAX C500 and C600 models. In case you’re wondering, Level 2 cache is a bit of high-speed memory – usually 256K to 1 MB – that lives near the PowerPC processor. The CPU uses it to cache instructions and data for quick retrieval rather than returning to the (comparatively slow) RAM and disk systems to get the same information over and over again.
You need this update if you use one of the above machines and you’re running Mac OS 7.6.1, or System 7.5.3 and the 54xx/64xx Update 1.1 extension. The update re-enables Level 2 caches on the systems, producing speed gains of as much as 30 percent in some circumstances. Although this patch is a tiny disk image file (11K), you’ll need Apple’s DiskCopy 6.1 (about 500K) to mount the image and drag the extension to your System folder. [JLC]