PowerPC 604

The PowerPC 604 is a series of PowerPC processors used by Apple Computer in their second-generation high-end Power Macintosh systems. They were also used by Macintosh clone manufacturers, including Power Computing, which had marketed them aggressively. These processors were developed by the AIM alliance, which included Apple, IBM, and Motorola.

Development history
The PowerPC 604 was designed for high-end workstations and supported multiprocessor configurations. It featured an 16KB instruction cache and 16KB data cache, twice as much as early PowerPC 603 processors. Its 64-bit floating point unit could also execute instructions in half as many cycles as the 603.

Processors

 * PowerPC 604 — introduced in the Power Macintosh 7600, 8500 and 9500 at 120 MHz and above.
 * PowerPC 604e — used in the updated Power Macintosh 7600, 8600 and 9500 at 180 Mhz and above. The 9500 offered a dual-processor option.
 * PowerPC 604ev — higher speed versions (250 MHz and above) used in the 8600 and 9600.

Successors
Motorola produced a PowerPC 620 with upgraded features of the 604 in the first full implementation of 64-bit PowerPC architecture. However, real-world performance was poor and it saw limited use as integer performance of the PowerPC G3 exceeded it. Some elements of the 604, such as the 64-bit floating point unit, evolved into the PowerPC G4.