March 1993 marked the beginning of a new era for the x86 microprocessor. The new CPU from industry leader Intel was launched : The Pentium! A lot was new with this processor, to begin with the CPU had a name. Instead of continuing the 86 coding scheme with 586, Intel decided to give their next generation of processors the name Pentium. Intel did this to differentiate their CPU’s from other manufacturers. They already tried to keep AMD from using 486 for their processor line but a lawsuite filed against AMD failed in court. AMD and other microprocessor manufacturers were allowed to use 486 for their CPU’s. The courts decision had to do with numbers being used for a name and that it was not possible to trademark a combination of numbers. The result was that Intel would use a name for their upcomming processor which could be trademarked. But Intel still named their 5th generation processor appropiately, Pentium is derived form the Greek word Penta which means 5.


The first version of the Pentium ,or Pentium classic as it is now known, had the code name P5 and version number 80501. It used a new socket, the 273 pin socket 4 and was manufactured at 0.80µ. Intel changed the introduction date several times, some say Intel had troubles with their BiCMOS manufacturing process and that yields as a result were very low. But it is also said that the demand for the 486 was still greater than the production capacity Intel had, so why should they introduce a new CPU?! They could affort to wait because they had a technical lead over their competitors.

At the introduction the Pentium was available in a 60MHz and a 66MHz version. The bus frequency was the same as the core speed and a major step forward from the 486 bus speeds of 25, 33, 40 or the rare 50MHz. Core voltage was 5v vcore and the packaging was PGA with or without headspreader.

Very interesting about the very first Pentium is the infamous FDIV bug. Somewhere at the end of 1994 the bomb exploded and everyone talked about it. A mathematicion, dr. Nicely who discovered the bug, had already informed Intel and then informed the press about it. The about six milion Pentiums manufactured until then had the bug and after heavy pressure from users, Intel had to give users the possibility to return their Pentium and receive a bug free one.


The next evolution of the Pentium processor was the P54 with version number 80502 which appeared a year later.This microprocessor had 296 pins and used Socket5. It was manufactured at 0.50µ and later (from 120MHz) at 0.35µ, voltage was 3.3v vcore. Available speeds were 75, 90 and 100MHz in PGA packaging with heatspreader and later all ceramic, 120, 133, 150MHz only in all ceramic and 166 and 200MHz versions in PGA and PPGA. Performance wise this Pentium had a lot to offer over the 486, but it also showed that a fast PC needs more than a high MHz CPU. For instance; the Pentium 150MHz had a front side bus of 50 MHz, that slow fsb made the P 150 only slightly faster than a Pentium 133 which had a 66MHz front side bus but cost a lot less!


This version of the Pentium is now known as the Pentium MMX. It was more or less a redesigned, more efficient P54 with a larger L1 cache, 32Kb versus 16Kb, and the much hyped MMX instructions. The Pentium MMX has 4.5 milion transistors and was manufactured at 0.28µ. 

Intel introduced the Pentium MMX in January 1997 as the new Multimedia CPU with Multi Media eXtensions. The term Multi Media eXtensions could not be trademarked so Intel always used the term MMX, because that term was trademarked by Intel. But what exactly was MMX? MMX were the 57 new instructions of the P55 which enabled the processor to perform the same function on multiple pieces of data with one instruction. It is also known as SIMD, Single Instruction Multiple Data. 

The Pentium MMX was available in three speeds, 166, 200 and 233MHz. They used Socket7 and had a split voltage design which used 2,8v. Because of the redesign, and not nessecirily the MMX instructions, the P55 was faster on a clock for clock basis than the P54. A Pentium 166MMX would even outperform a Pentium 200 Classic. In the end MMX did not make much of a difference in terms of realworld performance boosts, only a handfull of application could take advantage of the new instructions. The 233MHz version was the fastest Socket7 CPU Intel had for desktop use.


Intel had always dominated the mobile processor market with their esspecially designed low power 386SL and 486SL processors. The Pentium line had their low power level with the Tillamook. It was manufactured at 0.25µ, ran at 2,5v/1,8v and used from two to five Watts. Available speeds were 166, 200, 233 and 266MHz. Packaging was PPGA and TCP. The Tillamook was the last and fastest version of the first Pentium.

The First Pentium line was available for 4 years, in that time Intel launched 4 different versions of the processor. Almost all the time it was the most powerfull desktop processor available only AMD’s K6 and the Cyrix 6×86 could equal or surpass the Pentium, but only until Intel launched higher clock speeds. May 1997 marked the official end of the Pentium with the introduction of the Pentium II at a speed of 233 and 266 MHz.

Available models :

  • Pentium 60MHz (P5, 80501), 1 x 60MHz
  • Pentium 66MHz (P5, 80501), 1 x 66MHz
  • Pentium 75MHz (P54, 80502), 1.5 x 50MHz
  • Pentium 90MHz (P54, 80502), 1.5 x 60MHz
  • Pentium 100MHz (P54, 80502), 1.5 x 66MHz
  • Pentium 120MHz (P54, 80502), 2.0 x 60MHz
  • Pentium 133MHz (P54, 80502), 2.0 x 66MHz
  • Pentium 150MHz (P54, 80502), 2.5 x 60MHz
  • Pentium 166MHz (P54, 80502), 2.5 x 66MHz
  • Pentium 200MHz (P54, 80502), 3.0 x 66MHz
  • Pentium MMX 166 (P55, 80503), 2.5 x 66MHz
  • Pentium MMX 200 (P55, 80503), 3.0 x 66MHz 
  • Pentium MMX 233 (P55, 80503), 3.5 x 66MHz