Understanding the Motherboard

Understanding the Motherboard

This section prepares you to meet the exam objective of identifying popular motherboards and their components, architecture, and compatibilities. I can’t overemphasize the importance of this material for the exam. It has its own domain in the exam blueprint, and it is reflected throughout the exam.

Every essential component directly or indirectly involved with making the PC function is either on, attached, or connected to the motherboard. For all intents and purposes, the motherboard is the computer. A computer without a motherboard is simply an empty metal box that just sits there.

The primary components of the PC attach or plug into the motherboard, which creates the functionality of the PC. The major components included on or connected to the motherboard include the CPU, memory, expansion cards, disk drives, keyboard, mouse, and monitor. You know — all of the really important parts of the PC.

By any other name, it’s still mother

The motherboard is often referred to as a systemboard (at one time there was a distinction between the two). A systemboard integrated video, audio, graphics, and other device support into the board’s architecture; a motherboard didn’t. IBM has always called its motherboard a systemboard. Apple Computer calls its motherboard a logic board, while a few others refer to theirs as a planar board. These terms are still around today; for the most part, they are interchangeable because most motherboards are now systemboards and vice versa. I favor the term motherboard, but I may call it a systemboard for variety.

A PC motherboard is a large printed circuit board that’s home to many of the essential parts of the computer, including the microprocessor, chipset, cache, memory sockets, expansion bus, parallel and serial ports, mouse and keyboard connectors, and IDE, EIDE, or SCSI controllers. The motherboard binds the PC’s operational components together. Even devices (such as printers, hard drives, and CD-ROMs) are either connected to or controlled by the devices or controllers on the motherboard.

A wide variety of shapes, sizes, and types of motherboards are available. Regardless of a PC’s age and its form factor (see “Motherboard form factors,” later in the chapter), at least one manufacturer probably produces a motherboard to fit it. Manufacturers attempt to set their motherboards apart from the others and increase their value by incorporating more or fewer controllers, expansion buses, processor sockets, external connectors, and memory slots. For consumers, a wide range of motherboards with a deep list of features is available to fit into an even wider range of PCs. However, if you don’t do your homework before buying a new motherboard, this wide range of selection can be bad news, and you can end up with lower-quality components than you want.

¬†Remember ¬†Motherboards and systemboards are manufactured under a number of competing standards. Each was designed to solve a particular design, engineering, or marketing problem. Motherboards come in every size — from tiny to huge. Some styles even divide the motherboard into several interconnecting pieces.

For the A+ Core Hardware exam, you need to know a lot about the various components that populate any motherboard, as shown on Figure. However, you need to know about only a few specific motherboard form factors and what differentiates them.

Click To expand
Figure: The primary components of a typical mother-board

Motherboard form factors

The shape, packaging, and to a certain extent, the function of a motherboard are defined by its form factor. Many different form factors are available — some are generally accepted in the industry and others are open to interpretation by manufacturers. However, the exam blueprint for the A+ Core Hardware exam lists only the three most commonly used motherboard form factors:

  • AT: This motherboard is patterned after the original IBM PC AT motherboard.

  • Baby AT: This motherboard is a smaller version of the AT form factor motherboard.

  • ATX: Similar in size to the Baby AT, the ATX adds features. This is the most often used form in today’s PCs. The ATX motherboard allows for easier installation of full-length expansion cards and cables and is easier to cool.

More information on each of these form factors is included later in the chapter in the section “Motherboard Sizes, Shapes, and Styles.”

The components on the motherboard

The motherboard consists of layers of components added to the basic circuit board, similar to the layers of a pizza. Using the pizza analogy, think of the motherboard as the crust; the components, which add its functionality, are the toppings. For the A+ Core Hardware exam, you need to know what makes up the crust and each ingredient. In this chapter, I cover the details of the motherboard and the chipset; the other major components of the motherboard have their own chapters (which is a clue of the importance of these topics).

In addition to the motherboard, processor, and CMOS, you need to know the components listed in Figure. These components are usually found inside the system unit. After they are installed, they are considered a part of the motherboard’s sphere of control.

Figure: Motherboard Components You Must Know for the A+ Exam


Where You Can Find It in This Book


Chapter 4“BIOS”

Bus architectures

Chapter 5“Bus Structures”

Cache memory

See “Caching In on a Good Thing” later in this chapter


Chapter 6“Microprocessors”


Chapter 7“Memory Systems”

Storage devices

Chapter 8“Storing Data”

Power supply

Chapter 9“Powering and Cooling the PC”

I/O ports

Chapter 10“Input/Output Ports”

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