Overview
The Pentium II microprocessor was largely based upon the microarchitecture of its predecessor, the Pentium Pro, but with some significant improvements.
Unlike previous Pentium and Pentium Pro processors, the Pentium II CPU was packaged in a slot-based module rather than a CPU socket. The processor and associated components were carried on a daughterboard similar to a typical expansion board within a plastic cartridge. A fixed or removable heatsink was carried on one side, sometimes using its own fan.
This larger package was a compromise allowing Intel to separate the secondary cache from the processor while still keeping it on a closely coupled back-side bus. The L2 cache ran at half the processor's clock frequency, unlike the Pentium Pro, whose off die L2 cache ran at the same frequency as the processor. However, the smallest cache size was increased to 512 KB from the 256 KB on the Pentium Pro. Off-package cache solved the Pentium Pro's low yields, allowing Intel to introduce the Pentium II at a mainstream price level. This arrangement also allowed Intel to easily vary the amount of L2 cache, thus making it possible to target different market segments with cheaper or more expensive processors and accompanying performance levels.
Intel notably improved 16-bit code execution performance on the Pentium II, an area in which the Pentium Pro was at a notable handicap. Most consumer software of the day was still using at least some 16-bit code, because of a variety of factors. The Pentium II went to 32 KB of L1 cache, double that of the Pentium Pro, as well. The Pentium II was also the first P6-based CPU to implement the Intel MMX integer SIMD instruction set which had already been introduced on the Pentium MMX.
The Pentium II was basically a more consumer-oriented version of the Pentium Pro. It was cheaper to manufacture because of the separate, slower L2 cache memory. The improved 16-bit performance and MMX support made it a better choice for consumer-level operating systems, such as Windows 9x, and multimedia applications. Combined with the larger L1 cache and improved 16-bit performance, the slower and cheaper L2 cache's performance impact was reduced. General processor performance was increased while costs were cut.
Read more about this topic: Pentium II