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July 19
Newer First To Fix G4 Problems with Six-Slot Power Macs

by Tim Wilson
Man About Town™
[email protected]

Newer Technology announced today that they have identified and corrected a major problem with several symptoms on older Mac systems. The problem occurs between G4 CPU upgrades and six-slot Power Macs (9500 and 9600) and six-slot clones (Daystar Genesis and Power Computing PowerTower Pro). The problem relates to an "illegal bus condition" triggered by the dual PCI bridges in the 9500 and 9600.

Previous Newer "firsts" include the first Power Macintosh processor upgrade, first G3 PowerMac processor upgrade and the first G3 processor upgrade for the PowerMac 6100, 7100 and 8100 series. Their latest G4 upgrades run at speeds of up to 500 MHz.

A little history
Many Mac users in digital video, high-end audio or heavy graphics imaging have continued to use their older, six-slot machines because they have more slots in use than Apple provides in its current machines. Keeping them in use also allows the maintenance of what is often large amounts of RAM and a variety of peripheral devices no longer supported on new Macs.

The need for speed among such users is obviously often greater than for the Macintosh population at large, which is what makes the option of adding a processor upgrade so attractive. Indeed, some now-defunct clone manufacturers like Power Computing were quite intentional about making upgradeable processors part of their appeal.

More than faster chips, Newer's upgrade cards have offered the prospect of faster access to memory and faster data throughput via wider busses, allowing for a wide range of overall system improvements. Some serious problems arose, however, in the first attempts to add the latest enhancements to these older systems from both clone manufacturers and Apple.

These problems have nothing to do with PCI cards or six-slot computers, but was simply a compatibility issue with some G4 CPU upgrade cards—not shocking when you consider that there were no G4s, or even G3s, in existence when the six-slot architecture of these earlier computers (known as "Bandit") was developed. Previous attempts to add G4 chips to Bandit systems caused the cache and the system memory get "out of sync" with each other, disrupting what's known as "coherency." Coherency issues will cause all sorts of problems, from corrupted data to crashing apps to total computer lockups.

The bottom line
For users who want the latest in processor speed without sacrificing slots, this is obviously big news. While many such folks are already skipping ahead to start scouting out Newer's newest offerings (which start at $349, available from the usual outlets, including Newer's Web site), others will want the details of just how Newer pulled this off. Three White Papers at Newer's Web site go into great detail indeed on a number of issues related to memory timing, access to the L2 cache and more:

Supported computers for the MAXpowr G4 upgrade are:

  • Apple PowerMac 7300, 7500, 7600, 8500, 8600, 9500, 9600;
  • UMAX J700 and S900 series;
  • Power Computing PowerTower Pro and PowerWave;
  • Daystar Genesis

For more information, visit http://www.newertech.com.

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