AMD Processor History: An overview from the K5 to the Athlon XP

AMD Processor History: An overview from the K5 to the Athlon XP


Actually, our insight into the processor history of AMD should only form a small part of our processor comparison. But it quickly became clear that even a very limited overview of AMD's last few years of development could not be dealt with in two sentences. Too many important and interesting details finally let the scope grow to a volume that was not previously planned, so we decided to publish the 'History' shortly before the review. And yet it was hardly possible to deal with every single development step down to the smallest detail. So our review begins in 1997, the year the last AMD K5 processor was released. Incidentally, with its 'performance rating' it draws a wonderful bow to the current top model, the Athlon XP.

1997: K5, the Pentium rival

AMD was founded in 1969 and is thus one of the grandfathers in the field of microelectronics. In the period from 1982 to early 1997, a total of 90 million x86 processors were sold. Between 1992 and 1997 alone, 50 million were introduced to the people. Demand was booming and interest in computers was unbroken due to falling prices. With the end of the 486 era and the call for new technologies and more performance, the guys sent out of the sunnyCalifornia put the K5 into the race, which despite some good approaches had little to oppose the former class leader 'Pentium' from Intel. The last K5 processor for the desktop market was the AMD-K5-PR166. The 'PR' in the name of the processor stood for 'Performance Rating' and should make it clear that this processor achieved at least the same or even better performance compared to an Intel Pentium 166 MHz.

The new AMD-K5 -PR166 processor delivers system performance equal to or better than a 166 MHz Pentium, as indicated by the P rating. The P-Rating, based on the Ziff-Davis Winstone 97 benchmark suite, provides the PC industry with a single, meaningful measurement of true system performance provided by the processor.

The price of the processor was upon acceptance from 1000 pieces at $ 167. Nowadays you can get an Athlon XP 1600+ processor for this money according to the current AMD price list. But despite enormous differences in performance, the nomenclature of both CPUs spans a wide arc, because the P-Rating experienced a rebirth at the end of 2001.


The following table shows both the first and the second generation of the K5 processor. The development of the K5 was largely inspired by SSA/5.

Designation P-Rating Clock frequency Bus speed x multiplier First K5 processor generation AMD K5-PR100 PR100 75 MHz 50 MHz x 1.5 AMD K5-PR120 PR120 90 MHz 55 MHz x 1.5 AMD K5-PR133 PR133 100 MHz 66 MHz x 1.5 Second K5 processor generation AMD K5-PR166 PR166 116.5 MHz 66 MHz x 2.5 (internal - 1.75x)

From this point of view, the K5 is the revised processor series of the SSA/5, but with the same clock rate thanks to some improvements could get a higher P rating. The PR of the K5 clocked at 100 MHz was now PR133 and no longer PR100, as was previously the case with the SSA/5, which was clocked at the same time.

In order to maintain the performance rating, the processor clock was simply half the system -Bus clock added. In the second generation of the K5 processor, the only representative of which was to be the K5-PR166, the performance rating was chosen as the product of the system clock with the multiplier. However, the external multiplier of 2.5 was interpreted internally by the processor as 1.75, so that the performance rating was a good 42% above the real clock rate of the processor.

On the next page: 1997: The debut of the K6