Computers in a Nutshell

Or,
"Everything You Always Wanted To Know About Computers, But Didn't Even Know How To Ask"

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Chapter 1: History

    Back in the early 1970s when I was a child, a "computer" was a monstrosity the size of a house, costing $1,000,000.00; only large corporations or government agencies could own one.
    At Orange Coast College in Costa Mesa, California, where I took some classes in the early 1970s, they had an IBM 360, then the king of the mainframes. Its CPU was the size of a walk-in deep freeze, its two hard disk drives were the size of kitchen stoves, and its five tape drives were the size of refrigerators. Its printer was as big as a washer/dryer set, and made more noise than an entire Laundromat! The computer room (about seventy feet square) looked very much like a fancy appliance warehouse. That was a "computer".

    Then, around 1973, the first "home computers" came out. A typical example of these early home computer was the "IMSAI 8080". This nifty machine had a front panel with lots of little lights to indicate the binary status of each bit of each register. It was programmable in machine language only. Needless to say, these early computers never attained widespread popularity.

    Then a year or two later, two gentlemen named "Steven" -- Steven Jobs and Steven Wozniak -- built a small computer in their garage in Silicon Valley which was programmable in a simple programming language called "Beginner's All-Purpose Symbolic Instruction Code", or BASIC. The first practical home computer, the "Apple II", was born. True, one still had to learn BASIC to use it, but BASIC is a lot easier than machine language, any day.

    In the middle and late 1970s, home computers proliferated, and prewritten software became the norm, rather than having to write your own programs in BASIC. One of the most popular computer lines of this era was the "Tandy Radio Shack", or "TRS" line.

    Then around 1979, The IBM corporation decided to enter the home computer market with a machine which would both out-perform other home computers, and also set hardware and software standards for future designers. This computer was the "IBM PC", and its big brother the "IBM XT". IBM hired an until-then obscure computer nerd named Bill Gates and his tiny company "Microsoft" to write the operating system for its new home computers. Bill Gates created what he called "MS-DOS", which was basically a stripped-down drastically-simplified version of UNIX (the operating system used by most large computer systems, both then and now), and sold limited rights to IBM, who resold it as "PC-DOS" with its PCs and XTs. But in a business blunder of enormous proportions, IBM failed to secure the copyrights on MS-DOS. Bill Gates retained those. This blunder changed the face of the computer industry drastically and forever, both for better and for worse./P>

    For Bill Gates wasted no time selling MS-DOS to a lot of other computer manufacturers, and soon Microsoft had a near monopoly on the world's small-computer operating systems. As IBM floundered, Microsoft and Bill Gates became enormously wealthy.

    In the mid 1980s, two things happened. Firstly, the two Steves, Jobs and Wozniac, struck again with a new computer called the Macintosh, which had a very user-friendly graphical operating system using cute icons instead of cryptical file names and command codes. And secondly, Microsoft immediately came out with it's own version of the Macintosh's operating system, and called it "Windows". (Well, Windows 2.0 and 3.1 were actually just "Graphical User Interfaces", not true "operating systems", to be precise... but that's a whole other story.) The long rivalry, continuing to this day, between Apple Macintosh, on the one hand, and IBM-compatible computers (all running MS-DOS and Windows) was born. Macintosh was always the more user-friendly, but IBM clones running MS-DOS and Windows have always been far more numerous, and have a far richer range of software and hardware available for them.
    And that brings us to the current day. Perhaps about 90% of the world's small computers are now IBM clones running Microsoft Windows 98, with the other 10% being all other computers combined. And the percentage of middle-class households owning a computer has risen from 0% in 1970 to about 75% in 1999. A huge change in a mere 29 years!

    And yet... many of us are still at a loss to know how to use a computer. The technology has changed so fast that we were not able to keep up. How does one go about learning to understand these contraptions known as "computers"??? Well, that's were I can help. Read on.

Chapter 2: Analog or Digital?

    Most-generally speaking, a "computer" is any device that "computes", or performs mathematical tasks. Computers exist in two basic types: "analog" and "digital". Analog computers use pysical quantities such as voltage, fluid pressure, stress, string tension, etc., which are proportional to -- "analogs" of, that is -- the numbers one wishes to process.

    Analog computers tend to be very application specific. One example is the diaphram in a gas pressure regulator. Another is the central mechanism of an automotive carburator. Another is a bow. (Double the pull-back distance, and you double the string tension, and consequently the force on the arrow, which doubles the take-off velocity. A very simple, elegant analog computer.)

    Digital computers, on the other hand, are much more versatile and non-application-specific. All of the home computers used today are digital. Digital computers work by converting all of the numbers they process into digits, usually binary digits. Thus to add 5 and 7, a digital computer calculates like this:

     00000101
    +00000111
    =00001100

    Binary (base 2) numbers are used because of the ease of designing digital logic circuits that use two primary voltage states called "Hi" and "Lo", and because of the ease of converting the basic rules of logic (which are based on "Yes / No" questions and answers) into digital circuitry, and because transistors switch back and forth between full-on and full-off much faster than they could track intermediate voltage values.

    So do you have to learn binary arithmetic to use a digital computer? No, not at all! But to understand what is actually happening inside that mysterious ecru-colored box on your desk, it helps if you know that the numbers are all converted into zeros and ones before processing.

Chapter 3: Bits & Bytes & Big Numbers

    All those individual ones and zeros your computer calculates with are called "bits", and most of those bits are oraganized into groups of eight, called "bytes". Thus a single bit is either a "1" or a "0", while a byte is any of 256 possible patterns of eight ones and zeros in a row. For example, the binary addition problem in the chapter above is actually one byte being added to second byte, to produce a third byte.

    To facilitate talking about large amounts of data, certain shorthand terms have come into use in computer circles. Specifically, the following prefixes have been adapted to indicate large numbers of things:

    Thus the phrase "five Kilobytes" means "five thousand bytes", and the phrase "seven Megabits" means "seven million bits".

    Also, "bits" is abreviated by a small "b", while "bytes" is abbreviated by a large "B". Thus "4GB" means "four billion bytes", while "4Gb" means "four billion bits", an important difference.

Chapter 4: Basic Home Computer Layout

    A home computer consists of several basic parts which work together. In this chapter we discuss those parts and how they function. Most of these parts are inside your computer. Don't be afraid to take the cover off your machine and take a look. (But don't set screwdriver to anything or move any jumpers until you know what you're doing!)

CPU

    The brain of your computer is an integrated circuit ("IC") called a "Central Processing Unit", or "CPU" for short. Some of the most popular CPUs in use today are:

    CPUs are rated by speed, which is measured in MegaHertz ("MHz" for short). One "Hertz" is one clock cycle per second, so "300MHz" means "300 million clock cycles per second". I recommend at least 300MHz to run today's software. I've used 200Mhz machines at work and they seem slow as hell.

The CPU is the brain-power of your computer, so be sure to get a computer with a decent one! I'd recommend nothing short of an AMD K6 or an Intel Pentium. If you want the absolute best, it's probably an AMD K6-3/500. This is a powerful CPU with a 64-bit internal bus, running at 500MHz. It runs about 2-3 times faster than most other popular CPUs in use today.

Motherboard

    Your CPU plugs directly into the main circuit board inside your computer, which is called a "motherboard", since it acts as "mother" to lots of ICs and plug-in cards. The motherboard holds the CPU, RAM and ROM memory chips (more on these later), plug-in cards, and connectors and cables heading off to all the other parts of your computer (keyboard, mouse, printer, hard disks, floppy disks, CD-ROM, etc.). If you buy a computer with a decent CPU, it will probably have a decent motherboard in it. If you build your own computer, however, you will have to shop for a motherboard which supports the kind of CPU you want to use. (But that is a topic for advanced computer afficionados only!)

RAM

    Your Read-Only Memory, or "RAM" for short, is your computer's short-term, scratch-pad memory. The contents of RAM dissolve the instant you turn your power switch off. Your computer uses RAM to hold all of its currently-running programs. The larger the capacity of your RAM, the more programs you can have running at once. If you plan on running Microsoft Windows 98 and several large applications programs designed for Win 98, then I recommend at least 128MB of RAM, and preferably 256MB. Many computers come with far less RAM in them, but if you use anything less than 128MB of RAM with today's modern software, you will get repeated error messages such as "Insufficient Memory To Open Program" and "Invalid Page Fault" and "Your system is running dangerously low on resources". I am currently using 64MB, and I get such errors if I run more than 2 or 3 programs at once. I really need 256MB.

Power Supply

    The "Power Supply" in your computer is that box with the fan in it, the power cord coming in the back, and all the wires hanging out on the inside of your computer. This is the "heart" of your computer. It provides all the power that drives your CPU, motherboard, and plug-in cards. The two popular types of power supply in use today are AT and ATX. The AT power supplies are an old but reliable design. The ATX power supplies have added features, such as turning your system on or off, or putting it in "sleep mode", by pressing keys on your keyboard rather than manually flipping the power switch.

ROM BIOS

    When you first turn a computer on, the first thing the CPU does is to start reading and executing whatever is in its "Read-Only Memory" ("ROM" for short). The ROM is the computer's main program. On simple application-specific computers (such as the ignition controller in your car), all of the computer's program is in the ROM. But in a home computer, only the most basic part of the program is in ROM. This is called the "Basic Input Output System", or "BIOS" for short. The BIOS tells the CPU how to interface with the keyboard, the mouse, the video monitor, the hard and floppy disks, the CD-ROM, the printer, and other hardware.

CMOS RAM

    The first thing the BIOS does is read your battery-supported CMOS RAM. The CMOS RAM contains your system settings, including the number of heads, tracks, and sectors on all of your hard disks, and other basic hardware information. BIOS needs this data so that it knows how to instruct the CPU to interface with your hardware. You can access your CMOS setup data by holding the DEL key down while turning your computer on, and keeping it held down until the CMOS setup screen pops up. But don't change anything in there unless you know what you're doing! If you enter the wrong data, your system may not start. When in doubt, read the manual for your computer or motherboard. If you can't find the manual, or you don't understand what's in the manual, call your vendor.

Hard Disk

    Your hard disk contains your operating system, your programs, and all of your data. I recommend nothing less than a 4GB hard disk, and 10-15GB disks are already common.


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Construction began on Wednesday October 6, 1999

Last updated Tuesday January 5, 2010.

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