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4. B. Most likely the device has an option ROM, because it works.

5. A. All hardware needs BIOS!

6. A. The long repeating beep and a dead PC most likely indicate a problem with RAM.

7. C. Davos should find the CMOS clear jumper on the motherboard and then boot the computer with a shunt on the jumper to clear the CMOS information.

8. D. Please don’t hand Richard a screwdriver! Having him load Optimized Default settings will most likely do the trick.

9. A. The CMOS battery is likely dying.

10. C. Windows stores device drivers in the Registry.

CHAPTER 8

Expansion Bus

In this chapter, you will learn how to

Identify the structure and function of the expansion bus

Describe the modern expansion bus

Explain classic system resources

Install expansion cards properly

Troubleshoot expansion card problems

Expansion slots have been part of the PC from the very beginning. Way back then, IBM created the PC with an eye to the future; the original IBM PC had slots built into the motherboard—called expansion slots—for adding expansion cards and thus new functions to the PC. The slots and accompanying wires and support chips on the first PC and on the latest and greatest PC are called the expansion bus.

The expandability enabled by an expansion bus might seem obvious today, but think about the three big hurdles a would-be expansion card developer needed to cross to make a card that would work successfully in an expansion slot. First, any expansion card needed to be built specifically for the expansion slots—that would require the creation of industry standards. Second, the card needed some way to communicate with the CPU, both to receive instructions and to relay information. And third, the operating system would need some means of enabling the user to control the new device and thus take advantage of its functions. Here’s the short form of those three hurdles:

Physical connection

Communication

Drivers

This chapter covers the expansion bus in detail, starting almost at the very beginning of the PC—not because the history of the PC is inherently thrilling, but rather because the way the old PCs worked affects the latest systems. Installation today remains very similar to installation in 1987 in that you must have a physical connection, communication, and drivers for the operating system. Taking the time to learn the old ways first most definitely helps you understand and implement current technology, terminology, and practices.

Historical/Conceptual

Structure and Function of the Expansion Bus

As you’ve learned, every device in the computer—whether soldered to the motherboard or snapped into a socket—connects to the external data bus and the address bus. The expansion slots are no exception. They connect to the rest of the PC through the chipset. Exactly where on the chipset varies depending on the system. On some systems, the expansion slots connect to the Southbridge (Figure 8-1). On other systems, the expansion slots connect to the Northbridge (Figure 8-2). Finally, many systems have more than one type of expansion bus, with slots of one type connecting to the Northbridge and slots of another type connecting to the Southbridge (Figure 8-3).

The chipset provides an extension of the address bus and data bus to the expansion slots, and thus to any expansion cards in those slots. If you plug a hard drive controller card into an expansion slot, it functions just as if it were built into the motherboard, albeit with one big difference: speed. As you’ll recall from Chapter 5, “Microprocessors,” the system crystal—the clock—pushes the CPU. The system crystal provides a critical function for the entire PC, acting like a drill sergeant calling a cadence, setting the pace of activity in the computer. Every device soldered to the motherboard is designed to run at the speed of the system crystal. A 133-MHz motherboard, for example, has at least a 133-MHz Northbridge chip