As most of you will know, Intel is the designer of the x86 architecture. Right up to the latest i7 model, all manufacturers have used (virtually) identical names for processors using this architecture. An 80386 manufactured by Intel, for example, was 100% pin compatible with an 80386 from IBM. The introduction of the 80486 processor marked a change in this convention. Cyrix, for example, offered an 80486SLC which was actually a souped-up 80386. The main advantage of the Cyrix chip was that it allowed existing ’386 motherboards to match the processing power offered by the then extremely advanced 80486DX processor. With the introduction of the Pentium and, a little later, the Pentium Pro, Intel dropped the use of the 80nnn number series to identify their processors. Instead, Intel switched to names which could be registered as exclusive trademarks. This means that a Pentium or Pentium Pro processor is invariably a processor produced by one of the Intel chip factories.
The manufacturers of Intel look-alike processors are, of course, not to be overlooked when it comes to development activity. Besides Intel, manufacturers like AMD, IBM, Cyrix and NexGen are offering processors which may be applied in PCs running the Windows operating system. An important drawback of this development is, however, that some microprocessors are tied to a certain motherboard type from the same manufacturer. The powerful NexGen processor, for example, will only run on, you guessed it, a motherboard manufactured by NexGen. By contrast, the current series of processors thrown at us by Cyrix and AMD will cheerfully run in almost any PC processor socket.
All processor manufacturers, with the exception of Intel (the reference, after all) conform with the so-called Prating system. This independent speed test (Ziff-Davis Winstone) is applied to measure and qualify the computing power of processors. A processor which matches a 150-MHz Pentium as regards computing power is given a P-150 rating.
For us plain users this kind of testing and rating system is of little use, and bound to create confusion, particularly if we remain aware of ongoing developments and the fact that the ‘distances’ between processor families may get larger.