Pentium III and a brief history of PC processors

Question: I see a lot of advances in the power of computers nearly every day, and a lot of great deals. My current system is equipped with an Intel Pentium II 300 Mhz processor. Now we are seeing Celeron and Pentium III and Xeon chips – what are the differences? There seem to be some really good deals on systems with Celeron processor systems. What benefits and disadvantages are there to each? The top-dog seems to be the 500 Mhz processor. Is there a limit to our need for speed? What does a good system need for the average home user? – D.W.

Answer: Let me walk you through the evolution of PC processors, and then I’ll get to your extended questions, the answers to which will send chills up your spine.

There were earlier Intel chips, including their first, the 4004, and the follow-up chip, the 8008. The 8080 chip was shipped in the first personal computer called the Altair, which was an electronics hobbyist personal computer (look down Memory Lane, at an Altair brochure including prices, here). Microsoft founders Paul Allen and Bill Gates wrote the BASIC programming language for it.

The personal computer revolution didn’t really start until Intel created a chip called the 8088 processor. At the same time they created the 8086, which was a slightly more advanced chip. These chips were used in the IBM PC, which became known as the XT. That was 1978.

The 286 was next. It was also known as the 80286 and was the first Intel processor that could run all the software written for its predecessor. Within six years of its release, an estimated 15 million 286-based personal computers were in use around the world.

In 1985, the first multi-tasking chip arrived. It was known as the 386. This multi-tasking ability allowed Windows to do more than one function at a time. It was a phenomenal hit.

The 486 generation of chips really advanced the point-and-click revolution. The processor was also the first chip to offer a built-in math coprocessor, which gave the central processor the ability to do complex math calculations, which is required for complex programs and advanced graphical displays.

When Intel lost a bid to trademark the 586, to protect its brand from copycats, it coined the name Pentium for its next generation of chips. Informally this chip is known as the Pentium Classic, but only to differentiate it from the Pentium MMX chip, which was the same chip, but with a new set of chip instructions that boosted multimedia performance.

The P6 architecture includes the Celeron chip, the Pentium Pro, the Pentium II and the Xeon chips. Each is based on the same fundamental architecture, but there are subtle differences. The Pentium II is essentially the Pentium Pro with MMX technology built in. The Celeron and Xeon chips are based on the Pentium II, but differ in what cache they use, and how.

First a bit about cache:

• Hardware cache is essentially a form of memory. It’s used to store frequently used data so it’ll load quickly when the processor needs it. Some memory caches are built into the architecture of microprocessor chips – the Intel 80486 chip contains 8K of memory cache, and the Pentium has a 16K of cache.
• Those internal caches are often called Level 1 or L1 caches. The Level 2 cache is a secondary cache. It is larger and can be slightly slower. It is usually 64 KB to 2 MB in size. The Celeron chip is cheaper because it has 128 K of L2 cache built into the chip. The Pentium II cache is 512K in size. The PII L2 cache is external to the chip itself and runs at half the clock speed of the processor. So the L2 cache in a PII 400 Mhz chip runs at 200 Mhz. Not so on the Pentium II Xeon chip. Its L2 cache is 1 Meg in size and runs at the same clock speed as the chip.

The Celeron chip is Intel’s budget chip. The Pentium II chip is good for standard home or office usage and the Xeon chip is typically used for heavy-duty applications such as rendering animation or as a server. Clock speed, by the way, is a measurement of the chip’s processing speed. One MHz is equal to 1 million cycles per second. A cycle is the time it takes to execute one instruction, so a 400 MHz chip can perform 400 million instructions a second.

The Pentium III processor, which is the latest Intel chip, is based on the Pentium II architecture, except that it has a whole new series of multimedia instructions built into it to accelerate audio, video, and other applications. “We saw a trend in marketplace to a move to heavy Internet usage and technology that uses streaming to move data around on the Internet,” said Doug Cooper, Intel’s Canadian marketing manager. “We design the Pentium III to give better performance with Internet activity and voice recognition.”

I’ve described the new Pentium III extensions before as MMX on steroids, but Cooper said while Intel tries not to associate the new extensions with MMX, the analogy isn’t far off. The company has worked with Web browser plug-in developers to use the new Pentium III commands (known as SIMD extensions) to make Web-based multimedia more fluid (plug-ins are add-on bits of software that improve the functionality of a Web browser).

So what does a household need in a computer? I always say buy what you can afford, and if possible, go with the second best technology on the market. That gives you at least 18 months of use out of your computer without worrying that new software titles will overtake the capability of hardware in your PC. I bought a Pentium II 400 MHz Dell when the best system on the market was a Pentium II 450 MHz. With the money I saved, I doubled up the memory on board from 128 Megs of RAM to 256 Megs.

By the end of the year, you’ll see a Pentium III machine with clock speeds in excess of 550 MHz on the market, Cooper said. Intel recently demonstrated a prototype Pentium III 1000 MHz processor at a trade show. Expect that on the market toward the end of the second half of 2000. The chip is codenamed Merced and has a 64-bit architecture. That means that chunks of data zip around in 64-bit chunks, as opposed to 32-bit chunks in existing Pentium II and Pentium III chips.

If you want to look into the future, peek at the book The Age of Spiritual Machines: When Computers Exceed Human Intelligence by Ray Kurzweil, which theorizes that we will see a $1,000 computer with the same computing power as the human brain by 2019, a prediction based on an extrapolation of the rate of current chip improvements.