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INTRODUCTION

Several years ago our hospital installed new personal computers throughout patient care areas. The machines are used for order entry, patient tracking, lab and radiology information, literature searches, and Internet access. When they were initially installed, they were quiet. Today, however, many of them have developed a continuous, high-pitched whine. Many of the health care professionals who use these computers as a part of their daily activities don’t have any idea what the noise might be. Some of them aren’t aware of the fact that there are more moving parts in a computer than those associated with the floppy drive. Most of them are not aware that this noise might be a problem.

A computer is like a living organism in many ways. Its anatomy is relatively consistent across brands. Computers sicken, age, and eventually die. There are ways to diagnose illness in a computer that refer back to its parts and their function. Like a cardiac murmur, the whine in an aging computer can only come from a moving part. Since the whine is continuous, and continues when the floppy drive is not being accessed, it must originate from a part that is moving continuously. This can only be the cooling fan or the hard disk drive. If it is the hard disk drive, and it is a new or worsening sound, it may imply that the drive is at risk for a catastrophic failure and therefore loss of the data on the drive. While this may not be particularly interesting to the individual practitioner when the computer belongs to the hospital, it becomes much more compelling when you own the computer and its data.

This chapter describes the anatomy of a generic computer, what each part does and how it works. The information is sufficiently generic that it applies to virtually all PCs including those manufactured by Apple, IBM, Dell, and others.

Before starting any discussion about hardware, a brief discussion about how computers work is in order. Computers are made of electrical circuits that are designed to understand and do things based on binary numbers—numbers where each digit is either a 0 or a 1. In the computer a 0 is represented by one electrical voltage (3.3 V) and the 1 by another (5 V). Each binary digit is called a bit, and bits are grouped together in bytes (usually 8 bits long). Depending on the context, a byte can be used to represent a number, a character, a portion of an image or an instruction. Instructions are grouped together to make programs (like a word processing program) and programs operate on groups of data (like a text document). Computers are incredibly fast and many processes (e.g., video display management and word processing) are performed in parallel, but it all comes down to electrical bits moving around in an organized fashion through a machine (Fig. 1-1).

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