Intel Pentium

Microarchitecture: P5

Kicking off Intel's P5 architecture, the Pentium served as an overhaul of the x86 line, not only abandoning its namesake "x86" branding,
but also bringing about a new superscalar architecture that was able to execute many instructions per clock.

In total, though the underlying architecture remained largely the same, there would be roughly four major variants of the P5 architecture: The P5, the P54C, P54CS, and P55C, with a fifth variant codenamed "Tillamook" integrating a 430TX chipset onto a mobile CPU module.

Variant: P5
The P5 is the first major architecture for the original Pentium. Technically known as i586 (to carry on the x86 moniker), the P5 marked the beginning of a new era for Intel.

Variants: P54C, P54CQS/CS, P24T
The P54C served largely as a process shrink for the original P5 architecture, bringing with it also a new socket: Socket 5, incompatible with the previous Socket 4 used by the original P5. The succeeding P54CQS/CS would also mark the use of smaller manufacturing processes, although they migrated to Socket 7, which this time was backwards-compatible with Socket 5. The P24T, also known as the "Pentium OverDrive", was a drop-in upgrade for older 486-based systems that contained a modified P54 core that was compatible with the 32-bit 486 bus, contained double the L1 cache, and contained an integrated heatsink, fan, and power regulator.

Variants: P55C, P54CTB
Also known as the "Pentium w/MMX™ tech" or "Pentium with MMX Technology", the Pentium MMX's P55c microarchitecture served as an iterative improvement over the original Pentium's P5 and its variants. The P54CTB, or "Pentium OverDrive with MMX Technology" (whew, that's a mouthful!) is, as its name suggests, a Pentium MMX meant speficially for use in upgrading older Pentium-based systems that may otherwise not support a standard P55C Pentium.

The Pentium MMX's new features, namely its namesake MMX instruction set extensions, were primarily targeted towards multimedia functions. Along with this addition would came additional performance improvements to branch prediction, instruction decoding, and instruction pipelining.

Variant: Tillamook
An enhanced, mobile variant of the Pentium MMX/P55C core. The PCB that this core was commonly mounted on also contains a chipset and external L2 cache, but otherwise is simply a die shrink of the previous core.