Intel's NetBurst Architecture - The Pentium 4's innards get a name

Rapid Execution Engine

As we mentioned in our initial coverage of the CPU, the Pentium 4's Arithmetic Logic Units (ALUs) operate at twice the core clock frequency. This means that on a 1.4GHz Pentium 4, the ALUs are effectively running at 2.8GHz and on the 1.5GHz Pentium 4 demo we saw 6 months ago, the ALUs were effectively running at an impressive 3.0GHz. Intel refers to this feature as the NetBurst architecture's Rapid Execution Engine.

We predicted that this would give the Pentium 4 the clear advantage in Integer performance, however from our recent discussions with Intel, it seems as if the main reason for clocking the integer ALUs at twice the core frequency was to make up for the lower IPC of the NetBurst architecture.

While we can't release performance numbers today (those will have to wait until the CPU is actually released), remember that the Rapid Execution Engine might be necessary in order to make sure that the Pentium 4 can outperform the Pentium III in integer applications.

The biggest question most of you all had when we first mentioned the 2X clocked ALUs back in February was whether or not we'd see chips advertised at 3GHz just because their ALUs were effectively running that high or whether we'd see some processors with normally clocked ALUs and others with 2X ALUs. Our understanding of the matter is that Intel won't be doing anything like that, and the feature is simply a part of the NetBurst architecture. It would be very misleading if Intel attempted to pursue either of those avenues of marketing, and chances are that they won't.