Pentium II

Pentium II. The Pentium II was a x86 microprocessor introduced by Intel in May 1997 as the successor to the Pentium Pro. It represented a significant shift in packaging and marketing strategy, combining the core of the Pentium Pro with MMX technology and a new physical form factor. The processor was widely used in consumer desktop and workstation systems, becoming a defining product of the late 1990s personal computer market.

Overview

The development of the Pentium II was driven by the need to improve upon the Pentium Pro's performance in 16-bit code while integrating the newly popular MMX multimedia extensions. Under the leadership of executives like Craig Barrett, Intel sought to create a more marketable product for mainstream users. Its launch was a major event in the industry, competing directly with offerings from AMD and Cyrix. The processor's distinctive SECC packaging, often called a "slot processor," set it apart visually from all previous x86 designs.

Architecture and features

Architecturally, the Pentium II was based on the P6 microarchitecture first seen in the Pentium Pro. It featured a decoupled, 12-stage instruction pipeline and employed an advanced form of speculative execution and out-of-order execution. A key addition was full support for the MMX instruction set, which accelerated multimedia tasks. The design separated the CPU core and the L2 cache onto a substrate within the cartridge, connected via a dedicated back-side bus. This cache, typically 512 KB, ran at half the speed of the core processor. The chip also maintained support for the Socket 8 platform's dual-processing capabilities in certain server-oriented variants.

Models and variants

The first iteration, codenamed "Klamath," was manufactured on a 0.35-micron process and ran at speeds from 233 to 300 MHz. It was followed by "Deschutes" (0.25-micron), which extended the frequency range up to 450 MHz and introduced a 100 MHz front-side bus. For the mobile market, Intel released the "Tonga" and "Dixon" mobile Pentium II processors, with "Dixon" featuring a large integrated L2 cache. A budget-oriented, socketed version for the low-cost market was later released as the Celeron, initially without any L2 cache. For the server and workstation segments, a variant named Pentium II Xeon was launched, featuring a full-speed L2 cache and support for the Slot 2 interface.

Performance and reception

The Pentium II offered substantially better 16-bit performance than the Pentium Pro, making it excellent for mainstream Windows 95 and Windows 98 software. Its MMX capabilities were well-received for gaming and early digital media applications. Reviewers from publications like PC Magazine and AnandTech praised its balanced performance. However, in some pure 32-bit server applications, the slower L2 cache could make it slightly less performant than an equivalent Pentium Pro. It faced strong competition from the AMD K6 series, particularly on price, but generally maintained a performance leadership in floating-point operations crucial for 3D gaming, especially with the Voodoo2 graphics cards of the era.

Successors and legacy

The Pentium II was directly succeeded by the Pentium III in 1999, which introduced the SSE instruction set. Its core microarchitecture continued through the Pentium M and profoundly influenced the Intel Core series. The SECC cartridge design was short-lived, as the industry returned to socketed processors with the Socket 370. The Pentium II cemented Intel's dominance during the peak of the Wintel alliance and was instrumental in powering the proliferation of multimedia-capable home computers. Its technology also formed the foundation for the highly successful Celeron brand, which brought affordable computing to millions.

Category:Intel microprocessors Category:x86 microprocessors Category:Computer-related introductions in 1997