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

The P4's bus, unlike the Athlon's EV6, isn't a Point-to-Point bus, meaning that all CPUs must share the same 3.2GB/s of available system bandwidth. With a Point-to-Point bus, although it's more complicated to implement, each CPU in a multiprocessor environment gets its own connection to the North Bridge meaning that in the case of the Athlon's EV6 bus, each CPU in a multiprocessor setup would get a 200MHz connection to the North Bridge.

Point-to-Point Bus Protocol - AMD EV6

Shared Bus Protocol - Intel NetBurst Bus

Intel also informed us that the Pentium 4 would strictly be a uniprocessor part, meaning it won't even work in multiprocessor boards. We'll have to wait for the SMP version of the CPU, currently called Foster, before we can see what the Pentium 4 can do in a multiprocessor environment. Its 400MHz FSB should help considerably in dual processor systems which are currently forced to share a 100MHz FSB, at least on Intel platforms.