The PowerPC 604e

The 604e built on gains made by the 604 with a few core changes that included a doubling of the L1 cache size (to 32KB instruction/32KB data) and the addition of a new independent execution unit: the condition register unit (CRU).

The previous 600-series processors had moved the responsibility for handling condition register logical operations back and forth among various units (the integer unit in the 601, the system unit in the 603/603e, and the branch unit in the 604). Now with the 604e, these operations got an execution unit of their own. The 604e sported a functional block in its back end that was dedicated to handling condition register logical operations, which meant that these not uncommon operations didn’t tie up other ...

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