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Creating A Thinking World with John Chaffee, Ph.D. @www.thinkingworld.com |
Computer Performance:
More Info On CPUs
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There are many CPUs out there. The major manufacturers for personal computers (oh! That's what the "pc" stands for!) are Intel, AMD, and Motorola. Intel's newest chip is the Pentium III. Intel has historically made CPUs for Windows PCs, and you can deduce quite a bit from their numbering system. Intel chips were called 80286 chips or 286s in the late 80s, and improved to 80386 and 80486 chips in the early 90s. The 80586 chip was called the Pentium, and the 80686, and 80786 were called the Pentium II and Pentium III. While the 486 CPUs usually ran at about 66 MHz, the current Pentium IIIs (sometimes advertised as just PIIIs or P3s) run at speeds of up to 800 MHz! One of the reasons that this improvement has been constant over the years is that other manufacturers have provided competition. AMD makes its own processors, which usually are comparable in speed to their Intel counterparts. Their CPUs are usually designated as K-5, K-6, and now K-7 CPUs. In addition to constantly improving the performance of its Pentium line of processors, Intel has come out with a lower powered processor called the Celeron. It was meant to be a low cost substitute for the Pentium. Originally, Celerons lacked an on-board cache (see cache) and that hurt the speed significantly. As a result, machines equipped with a Pentium II processor were faster than Celeron processors running at the same clock speed. Also, Celeron processors used the slower (66MHz) bus, which slowed the performance further. Currently, Celerons have improved significantly. They now sport an on-board cache, and they are running at much higher clock speeds. The Celerons have become an excellent option for people buying notebook computers since they lower the price of the unit considerably without noticeably hurting the overall performance. Motorola makes the processors for Apple's Macintosh computers. The latest CPU made by Motorola for Apple was the PowerPC chip, which went into all of the Power Macintosh computers. These processors greatly enhanced system performance, and the PowerMac became the first desktop PC to outperform Windows/Intel machines. The PowerPC processor is a RISC chip meaning that it actually reduces the number of instructions necessary to complete tasks. This speeds up overall performance noticeably, especially when using programs that were optimized for this platform. The current PowerPC chip is the G4 or fourth-generation PowerPC processor. These processors are the successors to the G3 (3rd generation), and reach clock speeds of up to 500 MHz. The reduced instruction design of the PowerPC chip brings up another point. Not all clock speeds are created equal. As the architecture of the processors improves there are improvements that may not show up on paper. For example, because of performance enhancements made by Intel, an 80486 CPU (or later) would be 20 times as fast as an 80286 CPU running at the same clock speed. Does this mean that it's always best to have the newest processor? Not necessarily, but it does pay to ask about the improvements made from one generation of CPUs to the next. |
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