Processor History

Dennis Faas's picture

This week I received a question from one of our visitors which asked, "What is the difference between the Pentium, Celeron, and Athlon processors?" To best answer this question, we must first understand a bit of processor history, starting with Intel's flagship processor, the Pentium.

In 1993, Intel brought the PC to a new level with the Pentium processor. The first Pentium processor ran at an astounding 60 Mhz, had 3.3 million transistors, and performed 100 Million Instructions Per Second (MIPS). Although no one today refers to the first Pentium processor as a Pentium 1, it is the original of 4 types of Pentium processors developed by Intel.

Once the first Pentium processor technology became obsolete, the Pentium 2 was introduced. Starting at 233 MHz, the Pentium 2 took over its sibling's footsteps and was designed to run from 233 MHz to 450 Mhz. At about the same time, the Intel Celeron processor was presented; it was identical to the Pentium 2 except it was considered a "lower end" processor because of two main differences: a smaller cache and a slower bus speed. Cache is a special part of the processor which helps to process frequently used information faster; bus speed (also known as FSB or Front Side Bus) is responsible for the speed at which all parts of the computer communicate with each other. Bus speed has a dramatic effect on overall speed of the computer. In comparison, Pentium 2 processor had a 100 MHz bus, whereas the lower-end Celeron only operated at a 66 MHz bus.

Not too long after the introduction of the Celeron, the first Pentium 3 processor replaced the Pentium 2 and ran at 450 MHz. Both the Pentium 3 and Celeron processors are still in production today, reaching speeds up to 1260 MHz (or 1.26 GHz) and beyond. The Pentium 3 bus was first rated at 100 MHz but then increased to 133 MHz beginning with the 500 MHz model processor -- also known as the "500EB" model.

Even though AMD has been around for quite some time, AMD's popularity did not come into the spotlight until the introduction of the Athlon processor. At around the same time that Intel introduced their 600 MHz Pentium 3 processors, AMD wowed the world with the Athlon. The Athlon processor not only ran programs just as well as the Intel Pentium 3 and its predecessors -- its bus speed also ran twice as fast as the Pentium 3. AMD's groundbreaking technology utilized a dual bus, even though the clock-speed (MHz rating) was the same. AMD became a success story with the Athlon processor and, like Intel, began producing a lower cost processor -- the AMD Duron -- which also had less cache. In comparison to Intel's Celeron, the Duron still had a 200 MHz bus, while the Celeron ran only at a mere 66 MHz.

Today's Processors

As of late, AMD changed their processor architecture once more and has introduced their new line of Athlon processor: the Athlon XP. While still an Athlon processor, the major difference with the Athlon XP is that it does not use the conventional MHz rating to depict its speed. This is because AMD believes that a MHz rating would undermine its true performance and therefore wishes to change public perception. For those who insist of raw MHz numbers, AMD claims a 25% performance increase of their XP 1900+ compared to a Pentium 4 running at 1900 Mhz.

Since the word about AMD's success spread, Intel recently introduced the Pentium 4 with a groundbreaking speed of 1400 MHz. Although the Pentium 4 offers a bus speed of 400 MHz, the processor is still twice as expensive as the AMD's Athlon XP processor, while performing roughly the same, if not better.


The absolute most important aspect of AMD's Duron and Athlon processors is that they are half the price of Intel's Celeron and Pentium 3 and 4 processors and still outperform them in almost every instance.

AMD processors are also popular because they are extremely overclockable: that is -- with a good motherboard, they are able to go faster than what they are rated. For example: I own an AMD Athlon 850 MHz, but have it overclocked and running at 1000 MHz with a 266 MHz bus. While overclocking is an issue for the more technically inclined, I will simply state this as another reason for AMD's popularity.

Here's a quick reference chart depicting processor speeds, and their respective front side bus (FSB) ratings:

  • Pentium 1 60 - 233 66 MHz FSB
  • Pentium 2 233 - 450 100 MHz FSB
  • Celeron 300 - 66 MHz FSB up to Celeron 766 MHz
  • Celeron 800 - 100 MHz FSB
  • Pentium 3 450 - 100 MHz FSB up to Pentium 3 500 MHz
  • 133 MHz FSB starting with Pentium 3 533 MHz
  • Athlon 600 - 1400 AMD offers both 200 and 266 MHz FSB, depending on the type of RAM used: 200 MHz FSB = SDRAM, 266 MHz FSB = DDR RAM
  • Pentium 4 1400 - 400 MHz FSB (RDR RAM)
  • Athlon XP 1500+ 266 MHz FSB (DDR RAM)
Rate this article: 
No votes yet