Pentium Classic (P54C)

This chip was developed by Intel in Haifa, Israel. The processor is super scalar, meaning that it
can execute more than one instruction per clock tick. Typically, it handles two instructions per
tick. In this respect, we can compare it to a double 486. At the same time there have been big
changes in the system bus: the width is doubled to 64 bit and the speed is increased to 60 or
66 MHZ. This results in a substantial improvement from the 486 technology.

Originally, Pentium came in two versions: a 60 MHZ and a 66 MHZ. Both operated on 5 Volt.
This produced a lot of heat (it was said that you could fry an egg on them!) The next Pentium
(P54C) generation had a built in 1½ clock doubling, and ran at 3½ Volt. This took care of the
heat problem.

Since then, Intel carried two Pentium lines: those which run at 60 MHZ on the system bus (P90, P120, P150, and P180) and the best, which run at 66 MHZ (P100, P133, P166 and P200).


All modern CPU's share a common need for cooling. Make sure to include a good cooler. It has
to be matched to the size of the CPU.
  • It has to be attached properly, either with glue or a clamp, which fits the CPU.
  • It must have a substantial size heat sink - the bigger the better.
  • The fan must be mounted in roller bearings, to minimize noise.
The bigger the fan and heat sink, the better it is. The CPU will operate more reliably. It will have
a longer life span, and it can possibly be over clocked. If you buy Intel CPU's, buy them "in a
box". It is a special package, priced slightly higher than just the CPU. They always include a
good fan and a three year warranty.

Pentium with fan. Photo taken with Canon Powershot 600. JPG-file 1:30, 32 KB.

Pentium MMX (P55C)

MMX is a new set of instructions (57 new integer instructions, four new data types, and eight 64 bit registers), which expand the capabilities of the CPU. It is an addition to the original Pentium set of instructions.

The new instructions are designed for multimedia programs. The programmers can utilize these
instructions in their programs. These allow the Pentium to provide improved program execution. MMX is a new standard, which Intel will include in all their CPU's. Both Cyrix and AMD use MMX in their 6th generation CPU's (K6 and M2). Programs, which are written with MMX instructions, can still be run on, for example, a Pentium without MMX. However, execution is slower with the traditional instructions.

More L1 cache and higher clock frequency

The new P55C Pentiums are further improved with 32 KB L1 cache (the old had 16 KB). This initself is a good feature. There are also other improvements in the CPU. These improvements should provide 10-20% better performance than the old CPU's.

Dual voltage
P55C requires a new system board. Not because of MMX - that is pure software, but because
of changes in the power supply. P55C operates with dual voltage technology. To reduce heat
generation, this chip requires two different voltages: 2.8 Volt to the nucleus and 3.3 Volt to the
I/O section. The old system boards for the P54C's have only one voltage to the CPU. Thus, the
new CPU requires a new system board.


This is a low cost alternative to Pentium. The chip from the Cyrix company, which was
purchased by IBM in 1996, is a cheap Pentium copy.

The chip is Pentium compatible, since it fits in a socket 7, which is the Pentium connection to
the system board. When Cyrix suggests a 6th generation, it is because the 6X86 employs
advanced techniques, which are not found in Intel's Pentium. Thereby Cyrix gets improved
performance from their chip with the same clock speed. They market their CPU's with a
comparison to Intel's clock frequency.

As mentioned, the 6x86 chips have a lower internal speed than their name suggests. Below,
you can see the data for the different models