Pentium “Deschutes”

A 333MHz incarnation of the Pentium II, codenamed Deschutes after a river that runs through Oregon, was announced at the start of 1998, with 400MHz and higher clock speeds planned for later in the year. The name Deschutes actually refers to two distinct CPU lines.

The Slot 1 version is nothing more than a slightly evolved Pentium II. Architecture and physical design are identical, except that the Deschutes Slot 1 part is made using 0.25-micron technology introduced in the autumn of 1997 with the Tillamook notebook CPU rather than the 0.35-micron fab process which is used for the 233MHz to 300MHz parts. Using 0.25 micron means that transistors on the die are physically closer together and the CPU uses less power and consequently generates less waste heat for a given clock frequency, allowing the core to be clocked to higher frequencies.

Everything else about the Slot 1 Deschutes is identical to a regular Pentium II. Mounted on a substrate and encased in a single-edge contact (SEC) cartridge, it incorporates the MMX instruction set and interfaces with its 512K secondary cache at half its core clock speed. It has the same edge connector and runs on the same motherboards with the same chipsets. As such, it still runs with the 440FX or 440LX chipsets at 66MHz external bus speed.

In early 1998 a much larger leap in performance came with the next incarnation of Deschutes, when the advent of the new 440BX chipset allowed 100MHz system bus bandwidth, reducing data bottlenecks and supporting clock speeds of 350MHz and above. By early 1999 the fastest desktop Pentium II was the 450MHz processor.

The other processor to which the name Deschutes refers is the Slot 2 part, launched in mid-1998 as the Pentium II Xeon processor. Intel has pitched the Slot 1 and Slot 2 Deschutes as complementary product lines, with the Slot 1 designed for volume production and Slot 2 available for very high-end servers and such like, where cost is secondary to performance.

The table below shows the various incarnations of the Pentium II processor from its launch in 1997 up until the introduction of the Pentium Xeon:

Date Codename Transistors Fabrication (µm) Speed (MHz)
1997 Klamath 7,500,000 0.28 233/266/300
1998 Deschutes 4,500,000 0.25 333/350/400