PATHHardware Documentation > PowerBook G3 Series 1999

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G3 Microprocessor

The current family of PowerPC microprocessor designs is called "G3," for "generation three." The G3 microprocessors have several features that contribute to improved performance, including:

• larger on-chip (L1) caches, 32 KB each for instruction cache and data cache
• a built-in cache controller and cache tag RAM for the L2 cache
• a separate backside bus for the L2 cache, providing faster clock speed and overlapped bus transactions
• a microprocessor core optimized for Mac OS applications

The G3 microprocessor in the PowerBook G3 Series 1999 computer runs at a clock speed of 333 or 400 MHz. Table 2-1 shows how the speeds of the CPU clock, the backside cache, and the main memory bus are related.

The PowerPC G3 family of microprocessors includes the PowerPC 740^TM and the PowerPC 750^TM ; the PowerBook G3 Series computers use the PowerPC 750.