A+ Certification / Beginners

---

Looking at Popular Intel Processors

In this section, overview of the Pentium-class processors and their characteristics, including data bus, address bus, registers, and the amount of cache memory supported on these processors. You will also be introduced to any new or unique processor features that each processor offers.

Pentium

The original Pentium processor was released in 1993 and was developed at speeds of 60 MHz and 66 MHz. The Pentium processor was a PGA chip that was placed in Socket 5 or Socket 7. Soon after its release, Intel marketed Pentium processors in 75 MHz, 90 MHz, 100 MHz, 120 MHz, 133 MHz, 150 MHz, 166 MHz, and 200 MHz flavors, which were really just clock multipliers of the original 60 MHz or 66 MHz systems.

Clock multiplying is the concept that the processor will run faster than the motherboard that the processor sits in. For example, the original Pentium processor ran on 60 or 66 MHz motherboards. Say that the computer is marketed as being a Pentium 90. Since we know that the motherboard runs at 60 or 66 MHz, we can determine that the 90 comes from 60 * 1.5 - meaning that the processor runs 1.5 times the speed of the motherboard. This is important because, as a consumer, when you purchase a computer, you want to make sure you know what the motherboard speed is, too, not just the advertised speed of the processor.

From a consumer's point of view, clock multipliers become important when you take a look at computers such as the Pentium 133 and the Pentium 150. Which is faster? The obvious answer is the Pentium 150, the system with the higher megahertz speed. But is it really? The Pentium 133 is a clock double of the 66 MHz board, while the Pentium 150 is a clock double and a half of the 60 MHz board. My point being that the overall performance of the system is controlled by more than just the speed of the processor - you need to consider other components such as the speed of the motherboard.

By looking at the motherboard speeds of the Pentium 133 and the Pentium 150, you could assume that the computer running the Pentium 133 may be able to keep up with, if not outperform, the one running the Pentium 150. Table below compares the speed of the motherboard and processor for the different Pentium systems.

Pentium Clock Multipliers

Processor	Motherboard Speed (MHz)	Multiplier	Processor Speed (MHz)
Pentium 90	60	1.5	90
Pentium 100	66	1.5	99
Pentium 120	60	2	120
Pentium 133	66	2	132
Pentium 150	60	2.5	150
Pentium 180	60	3	180
Pentium 200	66	3	198
Pentium II	100	4.5	450

The Pentium processor has a 32-bit address bus, 32-bit registers, and a 64-bit data bus. It also has 16K of L1 cache that is divided into two 8K channels. One channel is for data cache and the other for application code cache.

Before the Pentium came along, processors used one instruction pipeline. This meant that when an application executed, it would run each stage of the application job one step after the other. For example, if an application has three lines of code each line of code can only be processed after the previous line of code is fully completed. This creates a delay, or wait time, that slows performance.

The Pentium processor introduced a feature called superscalar design, which is the fact that the processor has two instruction pipelines, named U and V. Having two instruction pipelines enables the processor to execute two instructions at the same time. Thus, the three lines of program code can be quickly executed on a Pentium processor because Lines 1 and 2 are processed at the same time, causing Line 3 to be processed that much sooner. Notice that Lines 1 and 2 execute parallel to one another; therefore, parallel processing is taking place.

An application has to be designed to take advantage of two instruction pipelines. These applications are often labeled something like "Pentium Aware" or "Pentium Ready."