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System Processing Core

The heart of any PC is what I call the system processing core. This set of critical components forms the logical center of any PC, and is responsible for most of the key characteristics that make a system what it is. The system processing core includes the following components:

• System processors (also called central processing units or CPUs).
• Motherboards (along with their many constituent devices such as the chipset, system buses and so on).
• System memory.
• Video cards. (The video card is also part of the video subsystem, but on modern systems so much processing can be "offloaded" from the CPU to the video processor that it can in many ways be considered a core system device.)

It should come as no surprise that the processing core is the most important collection of components within any PC. Due to their central role, they are the first components that are specified when selecting or building a PC. In fact, they are the basis by which different systems are categorized. Whenever you buy or build a new PC, you will start by selecting the components that make up this processing core.

Of all the components in this group, the CPU gets the most limelight, though it is not clear that all this attention is warranted. You will usually hear people talk about a PC on the basis of the CPU--for example, a "Celeron II PC" or an "Athlon machine". In fact, in naming the CPU, the person is really telling you a lot about the entire processing core of the machine. Sometimes this is called the platform type of the PC.

While the CPU is certainly important, I consider the motherboard to really be the heart of any system. It contains the chipset, which is the logic that interfaces all the core components together. It interfaces directly to all the core components of the PC, and its capabilities enable or limit those of the overall machine.

In fact, today, the CPU family and the motherboard are more closely related than ever before. At one time, especially in the mid-1990s, you could get a motherboard that would run several different families of CPUs, from several different manufacturers. Today this is not really the case; different CPU families usually have different interfaces and require different chipsets. This means that the choice of CPU and motherboard are even more strongly linked than they were in the past. You will almost always select these two in conjunction.

The system memory plays a slightly more secondary role in this group of four. The memory is important to performance and must match the motherboard (really, the chipset). If you want a particular memory type, you have to make sure that the motherboard will support it. In practice, few people select a motherboard and CPU in this manner, because memory technology is just one factor in the overall performance equation.

Some might make a valid argument that the video card does not even belong in the same elite group with the CPU, motherboard and memory. It's true that some of its functions are rather mundane and not tied particularly tightly to the other core components. But the focus on video performance and capability continues to increase on newer systems, especially when it comes to 3D applications. More and more, instructions that were once executed on the main CPU are running on the dedicated processor on the video card. Video cards also come in different interfaces, and acceptance of a particular interface requires support from the chipset, tying their selection inextricably to the choice of motherboard.

Next: Video Subsystem

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