Unlike the Pentium III, which we looked at in March of 1999, the architecture of the Pentium 4 is the product of a serious redesign. Whereas the move from Pentium II to Pentium III added two million transistors, the Pentium 4 sports a whopping 42 million - 14 million more than the currently available Pentium III Coppermine processors. This massive increase in transistor count correlates directly with die size, so naturally, the Pentium 4 is significantly larger than its predecessor. As we have seen with past processor products, manufacturers normally strive to shrink the die, saving money and increasing the number of processors that can be fashioned from a silicon wafer. So why did Intel decide to make the Pentium 4 larger? Since the .13-micron process is not quite ready yet (and won't be until next year), the P4 will be etched using the same .18-micron, aluminum trace process as the Coppermine. It does not take a mathematician to realize that 42 million transistors will not fit in a smaller space than a current product with 28 million. The question then becomes - what purpose do the extra transistors serve?

For the first time since the Pentium Pro, Intel has revamped their micro-architecture; adding features that they say will allow them to deliver leading performance for the next several years. It is important to recognize the significance of this move, since we have not seen a micro-architecture change since the Pentium Pro was released about four years ago.

The first important point to consider is that processor performance is not determined solely by frequency (raw MHz). Rather, it is a function of frequency multiplied by IPC, or instructions per clock cycle. In order to overcome the frequency limitations of the P6 architecture implemented in Pentium II and III systems, Intel developed an architecture that slightly reduced the number of instructions per clock but also reaped significantly higher frequency capabilities. Several new features comprise the new architecture so in order to better understand the workings of the Pentium 4 we have broken them down individually.