Understanding Personal Computer Hardware

ISBN: 0-387-98531-X

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This book provides a thorough yet concise description of personal computer hardware operation, including its subsystems, components, and peripherals. The book contains easy-to-do experiments that readers can perform to actually see how things work. Understanding PC Computer Hardware can be read cover to cover or used as reference source.


In general, there seem to be two kinds of books on computer "literacy." The first type provides only superficial explanations of very general computer operations—albeit with very pretty pictures. However, these books hardly scratch the surface. While such a book may look impressive on the coffee table, it serves no real practical purpose (it doesn't help the reader make buying decisions, for instance), nor does it satisfy the truly curious.

The second type of computer literacy book goes into far more detail than most interested persons would care to see—discussing at length such things as the actual electrical signals and pinouts of computer chips, or including long tables of statistical data on certain types of hardware. These books tend to be written with relatively little regard for those of us who do not carry soldering irons around in our pockets.

This book attempts to strike a happy medium between these two extremes. It is for the reasonably intelligent, and definitely curious, person who wants to understand the workings of his or her personal computer, but who doesn't even own a soldering iron!

The book is aimed at those who have at least a nodding acquaintance with an IBM-style personal computer, enough to copy a file or use a word processor. While computer experience is not as important as the desire to understand, it is easier to stay motivated after having some experience with personal computers.

I do not intend this book to be an encyclopedia. It is definitely for reading, and then hopefully will serve as a future reference. The discussion will be heavily slanted to the operation of more recent PCs. Thus, for instance, while we will discuss the entire line of Intel microprocessors that were commonly used in PCs since their inception in 1981, we will go into some detail only for the Pentium and Pentium Pro microprocessors.

Why Read This Book?

This book is devoted to perhaps the single most important and exciting technological event to occur in our lifetimes—the advent of the electronic computer.

Throughout history, there have been only a handful of technological events that can be called truly revolutionary. The inventions of the printing press (circa 1450), the steam engine (circa 1700), the internal-combustion engine (circa 1800), the telephone (circa 1870), the automobile (circa 1890), the airplane (circa 1900), the radio (circa 1900) and the television (circa 1925) are examples that come to mind (their dates did not come to mind—I had to look them up). However, since these inventions took place before most of us were born, they are second nature to us, and we cannot imagine what it would be like to live without them.

We are now witnessing the beginning of a new technological revolution that will change the course of history. I don't know about you, but this is enough to peak my curiosity. I want to be, if not directly involved in contributing to the revolution, at least knowledgeable about what is happening.

It is one thing to be able to use a computer, say to construct a letter, or enter a few numbers into a spreadsheet, or compute the balance in a checking account. This is certainly a valuable skill that everyone who wants to be successful in the modern world will sooner or later need to acquire. This level of familiarity may be likened to the ability to drive a car.

Now, it may be argued that knowing how to drive a car is enough, but of course, you might get some disagreement from the person stopped at the side of the road because his or her car refuses to run. Maybe it is just a simple fuse that needs changing. But if the person doesn't know that a car uses fuses and that many cars carry spare fuses in their fuse boxes, then it may as well be a frozen engine!

In any case, there is good reason to have more than just a passing acquaintance with the operation of a personal computer. Here are some of the reasons that come to mind:

A Note About the Experiments

I have included a number of do-it-yourself experiments throughout the book. These experiments are designed to allow you to actually get involved in the learning process. I suspect that you may find these experiments more fun than you might first think, but not unless you take the plunge. The only thing you need to do before conducting your first experiment is read the appendix entitled Trying the Experiments.

Be assured that all experiments are short and I will lead you through the steps one-by-one. All you really need to do is follow the instructions. Also, none of the experiments tamper with anything that should not be tampered with. They are primarily confined to reading memory, or displaying characters on the screen, or fiddling with a floppy diskette. Have fun and become empowered.

A Note about Writing Style

I dislike books that are written in the first person singular (except for the preface). Perhaps it is just habit on my part, or perhaps it makes me feel that I am somehow not involved in what is going on. In any case, I want you to feel involved, so I shall use the term "we" to refer to you and me. On the other hand, there will be several occasions where I will want to refer to my own PC. I don't much like the sound of "the author's PC" and it sounds stupid to say "our PC" and so I will refer to "my PC."

A Very Brief History of Computers

The development of modern computing is taking place at what seems like an incredible pace. The first large-scale digital computer was conceived by Professor Howard Aiken of Harvard University in 1937, and was built by IBM in 1944. It was called the Automatic Sequence Controlled Calculator, and mercifully referred to as the Mark I. This mostly mechanical computer contained more than 750,000 parts, was 51 feet long and weighed over 5 tons! It took about 6 seconds to perform a single multiplication. (A modern Pentium PC can perform this multiplication in about one ten-millionth of a second!) The Mark II was built by Aiken in 1947, and IBM's SSEC computer was completed in 1948. The top speed of these machines was about 1 multiplication per second.

The first all-electronic computer (with no mechanical parts) was constructed in the winter of 1944–1945. It was called the Electronic Numerical Integrator and Computer, or ENIAC. The ENIAC could do 300 multiplications per second, but it was still a cumbersome monster, containing about 18,000 vacuum tubes. Machine design continued to improve, and a computer industry developed in the 1950s. By 1960, there were about 5000 computers in existence throughout the world.

The invention of the transistor (a miniature electronic switch) in 1947 sparked a revolution in computer design. Transistors were able to replace vacuum tubes in computers during the late 1950s. Since early transistors were about 1/200th the size of vacuum tubes, not only could computers be built on a much smaller scale, but they were much faster, since electricity did not need to travel as far. Computers based on solid-state transistors could do about 100,000 multiplications per second, and were far more reliable than those based on vacuum tubes.

In the 1970s, it became possible to place tens of thousands, or even hundreds of thousands of transistors on small silicon chips no larger than the size of a thumbnail. These so-called integrated circuits produced another revolution in computer design, and made possible the world of personal computing.

In 1981, IBM introduced its first personal computer. Since then, personal computers, or PCs for short, have gone through roughly five generations, each marked by improved performance and capabilities. Today's personal computers are no larger than a suitcase, and can perform over 100 million multiplications per second!

I would like to express my thanks to several product managers and engineers at several companies, who have graciously spent time helping me to clarify some of the technical issues discussed in this book. In particular, my thanks go to: National Semiconductor Corporation, Adaptec, Buslogic, Intel Corporation, Micron Technologies, VESA, EIA, Power Magic, NEC, Viewsonic and SyQuest.


 Chapter Headings
 1. Overview
      Physical Overview of the PC
      The System Unit
      A Functional Overview of the PC
      A Peripheral Overview of the PC
      Connecting the PC Components-Buses
      Support for Peripherals
      The I/O Revolution
      Standards Organizations
      The PC Hierarchy
 2. Bits, Bytes and Words
      Binary Strings
      Measuring the Performance of PC Components
 3. The PC Hierarchy
      Registers and I/O Ports
      The Language of the Microprocessor
      The System BIOS
      DOS Services
      Device BIOS and Device Drivers
      The Interrupt Vector Table
      Trapping an Interrupt
      High-Level Languages
      More on the BIOS
      More on DOS
      Microsoft Windows Also Has Service Routines
      The PC Startup Process
      The Disk Boot Process
      The Built-In Setup Program and CMOS
      The BIOS Data Area
 4. Motherboards and Buses
      General Remarks about Buses
      The Motherboard
      Logical View of the Motherboard
      PC Bus Types
      How Bus Speed Affects Performance
      PCs Are Interrupt-Driven
      Installing New Devices in a PC
 5. Input/Output
      I/O Modules
      I/O Processors
      The Mechanism of Communication
      CPU Involvement in the I/O Process
      More on Ports
 6. PC Supporting Systems
      Clocks and Timers
 7. The Microprocessor
      Overview of the Intel Family of Microprocessors
      Intel 8088 Microprocessor
      Intel 80286 Microprocessor
      Intel 80386SX and DX Microprocessors
      Intel 80486SX and DX Microprocessors
      The Pentium Microprocessor
      The Pentium Pro Microprocessor
      The Pentium II Microprocessor
      A Detailed Look at the Pentium Processor
      A Closer Look at the Pentium Pro Processor
      A Closer Look at the Pentium II Processor
      External (Level  Cache
      Other Caches
 8. Memory
      Memory Chips and SIMMs
      Random Versus Sequential Access
      Dynamic and Static RAM
      Flash RAM
      Nothing Is Perfect
      Memory Speed
      Parity Checking
      SIMM Packaging
      How Memory Works
      Logical Memory Organization
      Memory Blocks
      Real and Protected Modes
      Virtual 8086 Mode
  9. Keyboards
      Physical Operation
      Logical Operation
 10. Mice
      Physical Operation
      Mouse Protocols
      Mouse Interfaces
 11. Display Monitors
      Monitor Features
      Display Data Control
      Monitor Construction
      Display Resolution
      How Images Are Displayed-Raster Scanning
      Relationship Between Scan Rates and Resolution
      Multiscanning Monitors
 12. Display Adaptors
      Display Systems
      Overview of a Video Card
      Video Memory
      Text Modes
      Graphics Modes
      Video Memory Organization
      Describing Colors in Memory
      Graphics Accelerators and Processors
      Performance of a Video Card
      Dual-Ported Video Memory and Bandwidth
 13. Device Interfaces: Floppy, IDE and SCSI
      Interface Philosophies
      The Floppy Drive Interface
      The IDE Interface
      The SCSI Interface
 14. Hard Drives I: Physical Characteristics
      General Operation of a Hard Drive
      Cylinder/Head/Sector Geometry
      Drive Performance Issues
      Low-Level Formatting
 15. Hard Drives II: Logical Characteristics
      Disk Partitioning
      High-Level Formatting and File Systems
      The DOS (FAT) File System
 16. Floppy Drives
      The Floppy Disk
      Floppy Drive Operation
      Implementation of a 12-Bit FAT
      Floppy Cables
      Floppy Drive Alternatives
      Removable Hard Drives
      Other Types of Removable Storage
 17. The Parallel Interface
      The Parallel Interface Cable and Connectors
      The Standard Parallel Port Registers
      Parallel Interface Standards
 18. Printers
      Daisy Wheel Printers
      Dot Matrix Printers
      Ink Jet Printers
      Laser Printers
 19. Asynchronous and Synchronous Transmission
      Asynchronous and Synchronous Transmission
      Asynchronous Data Transfer
      Synchronous Data Transmission
 20. The Serial Interface
      Serial Port Address Assignments
      The Serial Interface
      The EIA/TIA-232 Protocol
 21. Modems
      Digital Versus Analog Signals
      Duplex and Echoplex
      Amplitude, Frequency and Phase
      Modulation Types
      Wave Harmonics
      Telephone Bandwidth 
      Error Detection
      Data Compression
      Measuring Data Transmission Rates
      ITU Modem Standards
      MNP Modem Standards
      Modes of Operation
      The Modem Command Set
      Modem Registers
      Result Codes
      Initialization Strings
 22. Optical Storage
      CD-ROM Drives
      CD-R Drives
      Magneto-Optical Drives
 A1. Trying the Experiments
 A2. Cache Designs
 A3. SIMM Chip Counts
 A4. How Memory Works
 A5. Real and Protected Modes
 A6. Sector Translation
 A7. How Data Is Encoded on a Disk
 A8.     Intel Microprocessor Quick
          Reference Guide
      Intel Microprocessor Evolution
      Microprocessor Ratings

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