Other Hardware

The usual way to communicate with the computer is to type messages on the computer's
On the original IBM PC, the keyboard contained 83 keys. In January 1986, IBM began selling a
fancier keyboard, which contained 101 keys:
3Esc3     3F1 3F2 3F3 3F4 3 3F5 3F6 3F7 3F8 3 3F9 3F103F113F123   
3  ~  3 ! 3 @ 3 # 3 $ 3 % 3 ^ 3 & 3 * 3 ( 3 ) 3   3 + 3       3    3        3        3        3    3       3    3   
3     3
3  `  3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 3 0 3 - 3 = 3 Backsp3    3 Insert 3  Home  3 PageUp 3   
3NumLock3 /  3 *  3  -  3
3LeftTab3 Q 3 W 3 E 3 R 3 T 3 Y 3 U 3 I 3 O 3 P 3 { 3 } 3  |  3    3        3        3        3    3   7  
3 8  3 9  3     3
3Tab    3   3   3   3   3   3   3   3   3   3   3 [ 3 ] 3  \  3    3 Delete 3  End   3PageDown3    3  Home
3 "  3PgUp3     3
3        3 A 3 S 3 D 3 F 3 G 3 H 3 J 3 K 3 L 3 : 3 " 3        3                                    3   4   3 5  3 6 
3     3
3CapsLock3   3   3   3   3   3   3   3   3   3 ; 3 ' 3   Enter3                                    3   '   3    3 '  3  + 
3          3 Z 3 X 3 C 3 V 3 B 3 N 3 M 3 < 3 > 3 ? 3          3             3        3             3   1   3 2  3 3 
3     3
3Shift     3   3   3   3   3   3   3   3 , 3 . 3 / 3     Shift3             3   "    3             3  End  3 "  3PgDn3  
3           3     3                           3     3         3    3        3        3        3    3     0      3 .  3     3
3Ctrl       3 Alt 3           Space           3 Alt 3     Ctrl3    3   '    3   "    3   '    3    3    Ins     3Del

Now IBM sells just that 101-key keyboard; it no longer sells the old 83-key keyboard.
The keyboard can print all the letters of the alphabet (from A to Z), all the digits (from 0 to 9),
and these symbols:
Symbol    Official name       Nicknames used by computer enthusiasts
               .         period                                  dot,
decimal point, point, full stop
               ,         comma                              cedilla
               :         colon                                   dots,     double stop
               ;         semicolon                     semi
               !         exclamation point   bang, shriek
               ?         question mark            ques, query, what, huh,
               "         quotation mark           quote, double quote,
dieresis, rabbit ears
               '         apostrophe                         single quote,
acute accent, prime
               `         grave accent                  left single quote, open
single quote, open quote, backquote
               ^         circumflex                         caret, hat
               ~         tilde                                   squiggle, twiddle, not
               =         equals                                  is,
gets, takes
               +         plus                                    add
               -         minus                                   dash,
               _         underline                     underscore,
               *         asterisk                           star,
splat, wildcard
               &         ampersand                     amper, amp,
and, pretzel
               @    at sign                            at, whorl, strudel
               $         dollar sign                        dollar, buck,
               #         number sign                   pound sign, pound,
               %         percent sign                  percent, grapes
               /         slash                                   forward slash, rising slash, slant, stroke
               \         backslash                     reverse slash,
falling slash, backwhack
               |         vertical line                 vertical bar, bar, pipe,
enlarged colon
               ( )  parentheses                   open parenthesis & close
parenthesis, left paren & right paren
               [ ]  brackets                           open bracket
& close bracket, square brackets
               { }  braces                                  curly brackets,
curly braces, squiggly braces, left tit & right tit
               <>   brockets                           angle brackets,
less than & greater than, from & to, suck & blow
For example, the symbol * is officially called an "asterisk". More briefly, it's called a "star". It's
also called a "splat", since it looks like a squashed bug. In some programs, an asterisk means
"match anything", as in a card game where the Joker's a "wildcard" that matches any other card.

In the diagram above, I wrote just the words "Shift", "Backsp", "LeftTab", "Tab", and "Enter" on
some keys; but to help people who don't read English, IBM put arrows on those keys.
The SHIFT key shows an arrow pointing up.
The BACKSPACE key shows arrow pointing left.
The TAB key shows arrows crashing into walls.
The ENTER key shows an arrow that's bent.
Stare at your computer's keyboard and find these keys:
Key                      Where to find it
TAB key             left of the Q key
BACKSPACE if 101 keys, left of INSERT key
                                   if  83 keys, left of NUM LOCK
SHIFT keys          if 101 keys, above the Ctrl keys
                                   if  83 keys, above Alt & CapsLock
ENTER key      if 101 keys, above right SHIFT key
                                   if  83 keys, above the PrtSc key
If a key has two symbols on it, the key normally uses the bottom symbol. To type the top symbol
instead, press the key while holding down the SHIFT key.
To type a number easily, use the keys in the top row of the keyboard's main section. (For
example, to type 4, press the key that has a 4 and a dollar sign.) Do not press the number keys on
the right side of the keyboard: they produce numbers just if the NUM LOCK key is pressed
beforehand, by you or the computer. If the NUM LOCK key was pressed to produce numbers,
and you want to stop making those keys produce numbers, just tap the NUM LOCK key again.

The keyboard contains special keys that help you do special activities (such as moving around the
screen while you type):
Key                 Usual purpose
"                             move up, to the line above
"                             move down, to the line below
'                        move left, to the previous character
'                        move right, to the next character
Home                move back to the beginning
End                      move ahead to the end
Page Up             move back to the previous page
Page Down move ahead to the next page
Tab                      hop to next field or far to the right
Enter                    finish a command or paragraph
Pause                    pause until you press Enter
Print Scrn          copy from the screen to paper
Shift                    capitalize a letter
Caps Lock      capitalize a whole phrase
Num Lock       use numbers on keyboard's right side
Scroll Lock    change how text moves up & down
Insert                   insert new character in middle of text
Delete                   delete the current character
Backspace      delete the previous character
Esc                      escape from a mistake
F1                       get help from the computer
F2, F3, etc.   do special activities
Ctrl                     do special activities
Alt                      do special activities
Some programs make those keys serve different purposes. Avoid those keys until you read the
details in later chapters.
When buying a keyboard, you have many choices. You can buy an XT keyboard (83 keys), AT
keyboard (101 keys), augmented AT keyboard (101 keys plus an extra copy of the backslash
key), or Windows 95 keyboard (101 keys plus 3 special keys that help run software called
"Windows 95"). You can buy a standard-size keyboard (with a ledge above the top row, for
placing your pencil or notes), compact keyboard (which has no ledge and consumes less desk
space), foldable keyboard (which folds in half, as if you're closing a book, so it consumes half as
much desk space when not in use), or split keyboard (whose left third is separated from the rest,
so you can have the comfort of typing while your forearms are parallel to each other). You can
buy a tactile keyboard (which gives you helpful feedback by making a click whenever you hit a
key), silent keyboard (which helps your neighbors by not making clicks), or spill-resistant
keyboard (which is silent and also doesn't mind having coffee or soda spilled on it).
The best split keyboard is the one made by Addison because it's tactile, requires little pressure,
and costs just $50 at Staples discount stores. Phone Joel Hudesman at Janesway (800-431-1348
or 914-699-6710) for the best spill-resistant keyboards ($30) and foldable keyboards ($70); get
free shipping by saying you've read the Secret Guide.

Graphics-input devices
If you feed the computer a picture (such as a photograph, drawing, or diagram), the computer will
analyze the picture and even help you improve it. To feed the computer a picture of an object, you
can use three methods.... 
Method 1: point a video camera at the object, while the video camera is wired to the
Method 2: draw on paper, which you then feed to an optical scanner wired to the computer.
Method 3: draw the picture by using a pen wired to the computer. The computerized pen can
be a
                         light pen, touch screen, graphics tablet, mouse, trackball, or
Light pens
A light pen is a computerized pen that you point at the screen of your TV or monitor. To draw,
you move the pen across the screen.
Light pens are cheap: prices begin at $20. But light pens are less reliable, less convenient, and less
popular than other graphics-input devices.
Touch screens
A touch screen is a special overlay that covers the screen and lets you draw with your finger
instead of with a light pen.
Graphics tablets
A graphics tablet is a computerized board that lies flat on your desk. To draw, you move either a
pen or your finger across the board. Modern notebook computers include a tiny graphics tablet
(called a touchpad or glidepad), stroked with your finger and built into the keyboard (in front of
the SPACE bar).
A mouse is a computerized box that's about as big as a pack of cigarettes. To draw, you slide the
mouse across your desk, as if it were a fat pen.
When you slide the typical mouse, a ball in its belly rolls on the table. The computer senses how
many times the ball rotated and in what direction.
The mouse was invented at Xerox's Palo Alto Research Center (PARC). The first company to
provide mice to the general public was Apple, which provided a free mouse with every Lisa and
Mac computer. Now a free mouse comes with each IBM PC and clone, too.
The nicest mouse for the IBM PC is the Microsoft Mouse. Its first version was boring. Then came
an improved version, nicknamed "The Dove Bar" because it was shaped like a bar of Dove soap.
It felt great in your hand; but trying to draw a picture by using that mouse - or any mouse - was as
clumsy as drawing with a bar of soap. The newest version of the Microsoft Mouse is nicknamed
"The Dog's Paw" because it's shaped like a dog's lower leg: it's long with an asymmetrical bump
(paw) at the end. It feels even better than The Dove Bar, unless your hand is too small to wrap
around it. Discount dealers sell it for $59. Other brands cost less; the cheapest cost just $10.
A trackball is a box that has a ball sticking out the top of it. To draw, just put your fingers on the
ball and rotate it. Some notebook computers have a trackball built into the keyboard.
Technologically, a trackball's the same as a typical mouse: each is a box containing a ball. For a
trackball, the ball sticks up from the box and you finger it directly; for a mouse, the ball hides
underneath and gets rotated when you move the box. The mouse feels more natural (somewhat
like gripping a pen) but requires lots of desk space (so you can move the box).
The trackball was invented first. The mouse came later and has become more popular - except on
notebook computers, which use trackballs and touchpads to save space.
A joystick is a box with a stick coming out of its top. To draw, you move the stick in any
direction (left, right, forward, back, or diagonally) as if you were the pilot of a small airplane.
To produce sounds, the typical computer uses a speaker (similar to the speakers in your stereo
system, but smaller).
The speaker is typically inside the system unit. Some computers use the speaker in your TV or
monitor instead. The newest computers come with a pair of external stereo speakers, which sit
outside the system unit and produce louder sounds. The fanciest new computers come with three
external stereo speakers: the third speaker is called the subwoofer and produces a big, loud,
booming bass.
Aesthetic computers, such as the Mac, can make speakers play nice music. IBM's first PC was a
boring business computer that produced just harsh beeps, but IBM's newest computers let you
produce sounds as good as a Mac by inserting a sound card (such as the Sound Blaster).
Fancy computers speak words by including circuitry called a speech synthesizer.
The newest computers come with a microphone. By using the microphone, you can make the
computer record sounds. For example, you can make the computer record the sound of your
voice and imitate it, so the computer sounds just like you!

You can connect your computer to a telephone line so your computer can chat with other
computers around the world! Here's how.... 
To let your computer chat with a computer that's far away, attach each computer to telephone
lines by using a "special device" that turns computer signals into telephone signals, and turns
telephone signals back into computer signals.
Turning a computer signal into a telephone signal is called modulating the signal. Turning a
telephone signal back into a computer signal is called demodulating the signal. Since the "special
device" can modulate and also demodulate signals, the device is called a modulator/demodulator
(or modem, which is pronounced "mode em").
Acoustic versus direct-connect
You can buy two kinds of modems.
The old-fashioned kind is a black box that has big ears on top, so that it can listen to the
telephone. Because of its big ears, it's called a Mickey Mouse modem or an acoustic coupler. It
usually costs $120.
The newer kind of modem plugs directly into the phone system, as if it were an answering
machine. It doesn't have any ears: it has telephone wires instead. It's called a direct-connect
modem. It usually costs under $100, and it's cheaper and more reliable than a Mickey Mouse
modem. It's more popular than a Mickey Mouse modem because it's better than a Mickey Mouse
modem in every way, except that you can't attach it to pay phones or to phones in hotel rooms.
Kinds of direct-connect modems
A direct-connect modem can be either external or internal. If it's external, it's a box that sits next
to your computer. If it's internal, it's a printed-circuit card that hides inside your computer.
Regardless of whether it's external or internal, a wire runs from it to the phone system.
Internal modems are more popular than external ones, because external modems typically cost
more and require that you buy a cable to run from the modem to the computer. But external
modems have the advantage of being easier to control, since they give you push-buttons and
blinking lights.
Many notebook computers include internal modems at no extra charge. So do some desktop
Most direct-connect modems have fancy features, such as auto-dial (which means the modem can
memorize the other computer's phone number and dial it for you) and auto-answer (which means
the modem automatically answers the phone whenever the other computer calls). A
direct-connect modem having many such fancy features is called smart. Nearly all modems sold
today are smart.
10 bits per character
To transmit a character, the modem usually transmits a 10-bit number, like this: 1001011101.
The first bit (which is always a 1) is called the start bit; it means "hey, wake up, and get ready to
receive the data I'm going to send you". The last bit (which is always a 1) is called the stop bit; it
means "hey, I'm done, you can go back to sleep until I send you more data". The eight middle bits
(such as 00101110) are usually called the data bits: they're a code that represents 1 byte of
information (1 character). So to transmit 1 character, the modem transmits 10 bits.
A traditional modem transmits 2400 bits per second (2400 bps). That speed is also called 2400
baud. Since 10 bits make a character, that kind of modem transmits 240 characters per second.
That speed is reasonably fast: it's about as fast as the average person can read.
Faster modems can transmit 9600 bits per second (which is 9600 bps, 9600 baud, 960 characters
per second). That's faster than you can read, but it's appropriate for transmitting documents that
you want to skim, programs that you want to run, and graphics.

Even faster modems can transmit 14400 bits per second. Since 1000 bits is called a kilobit, 14400
bits per second is called 14.4 kilobits per second (or 14.4 kbps or 14.4 kilobaud).
All those modems are obsolete. Now the most common speed for transmitting data is 28800 bits
per second, which is 28.8 kilobits per second (or 28.8 kbps or 28.8 kilobaud). Most modems sold
today are capable of going even faster, 33.6 kilobits per second, though most people are still
transmitting at just 28800 kilobits per second to be compatible with friends using older modems.
A few computerists still use ancient, primitive modems transmitting just 1200 bits per second
(1200 baud) or 300 bits per second.
If you buy a fast modem, you can tell it to go slower. For example, if you buy a 33.6-kilobaud
modem, you can tell it to go at eight popular speeds: super-fast (33.6 kilobaud), fast (28.8
kilobaud), medium-fast 14.4 kilobaud), medium (9600 baud), medium-slow (2400 baud), slow
(1200 baud), and super-slow (300 baud).
To communicate with a friend's computer, your modem must go at the same speed as your
friend's. For example, if you buy a 33.6-kilobaud modem but your friend has just a 300-baud
modem, your modem's software will detect the slowness of your friend's modem and
automatically downshift (slow down) to 300 baud.
Standards for modem communication have been invented by AT&T and a French-speaking
international committee called the Comit‚ Consultatif International T‚l‚graphique et
T‚l‚phonique (CCITT). Here's what they call their standards:
Speed          CCITT standard      AT&T standard
    300 bps         V.21                                    Bell 103
  1200 bps          V.22                                    Bell 212a
  2400 bps          V.22bis
  9600 bps          V.32
14400 bps      V.32bis
19200 bps      V.32terbo
28800 bps      V.34 (or V.fast)
For example, if you see an ad for a V.22-compatible modem or a Bell 212a modem, the ad is
trying to sell you a 1200 bps modem.
Notice that the second version of V.22 is called V.22bis, because bis is a French word that means
"2nd version". Notice that the third version of V.32 is called V.32terbo, because terbo is an
international word that combines the French "ter" (which means 3) with the English word "turbo"
(which means "fast").
Find all those terms confusing? That's why computerists say that "CCITT" really stands for
"Committee for Confusing International Telecommunications Terms".
Data compression
Modems sometimes use a shorthand notation that lets data to be expressed in fewer bits than
normal, so more data can be transmitted per second. The shorthand notation is called a
data-compression technique.
The most popular data-compression techniques are Microcom's MNP level 5 (which compresses
data to half as many bits as normal), Microcom's MNP level 7 (which compresses data to a third
as many bits as normal), and CCITT's V.42bis (which compresses data to a fourth as many bits as
normal). For example, if you see an ad for a 2400-baud modem with MNP level 5, that modem
will transmit about as much data per second as a plain 4800-baud modem.
You can send messages from your computer to fax machines around the world, if you buy a
fax/modem, which is a modem that can also send faxes. If the fax/modem is fancy, it can also
receive faxes and print them on your printer.
The typical modern fax/modem can transmit modem information (to other computers) at 33.6
kilobaud but transmits faxes (to fax machines) at just 14.4 kilobaud. It's called a
33.6/14.4-kilobaud fax/modem. (Most ads list the modem speed first, then the fax speed, because
the modem speed is more important.)
A few years ago, the most popular kind of fax/modem was slower: it transmitted modem
information at 2400 baud, faxes at 9600 baud. It was called a 2400/9600-baud fax/modem. More
briefly, it was called a 2496 fax/modem. Warning: though every 2496 fax/modem can send faxes
at 9600 baud, the cheapest 2496 fax/modems receive faxes at just 4800 baud - or can't receive
faxes at all!
The most famous modems are made by Hayes, which charges high prices. Other companies make
cheaper modems that imitate Hayes' and are called Hayes-compatible. Nearly all modems sold
today are Hayes-compatible.
For example, high-quality Hayes-compatible modems have been built by Everex and Practical
Peripherals. To avoid competition from those companies, Hayes sued Everex and bought Practical
Peripherals. So Everex had to pay Hayes a royalty (and eventually stopped selling modems), and
Practical Peripherals became owned by Hayes.
To pay less for a Hayes-compatible modem, get the ones made by Cardinal, Zoom, or U.S.
Robotics. For example, you can get a U.S. Robotics internal 33.6-kilobaud fax/modem for a net
cost of just $60 (after you receive a rebate). That price is from a New York discount dealer called
Tri State Computer (800-433-5199 or 212-633-2530; ask for David Rohinsky at extension 223).
COM1 versus COM2
A modem is an example of a serial device. You might own another serial device also, such as a
serial mouse or a serial printer.
The IBM PC can handle two serial devices simultaneously. The first serial device is called
communication device #1 (COM1). The second serial device is called COM2.
If you add a modem to your IBM PC or clone, you must decide whether to call the modem
COM1 or COM2.
Most hardware and software assume the modem is COM2. To avoid headaches, make the modem
be COM2. Here's how.
If the modem is external, run its cable to your computer's COM2 port. (If your computer doesn't
have a COM2 port yet, buy a serial interface card containing it.)
If the modem is internal, make sure the switch or jumper on the modem is set to the COM2
position; and make sure no other hardware in your computer system is called COM2. For
example, if your computer contains a serial interface card having a COM2 port on it, you must
disable the serial interface card's COM2 port (by moving a jumper or switch on it).
Avoid using COM3 or COM4, since the computer has trouble handling COM3 and COM4
reliably. (COM3 often conflicts with COM1, and COM4 often conflicts with COM2.)

Like a disk, a magnetic tape consists of magnetized rust. Just as you put a disk into a disk drive,
you put a tape into a tape drive.
Tape drives are slower than disk drives. To skip from the disk's beginning to the disk's end, the
disk drive's arm simply hops from the outermost track to the innermost track. But to skip from the
beginning of a tape to the end of a tape, you must wait for the tape drive to wind the entire tape.
Cassettes for primitive computers
The cheapest kind of tape drive is an audio cassette tape recorder - the same kind you use for
listening to music, at the beach or in your car. You can attach that kind of tape recorder to an old
Radio Shack computer (such as the Radio Shack TRS-80 model 1, 3, or 4 or the Radio Shack
Color Computer). Wires run from the tape recorder to the computer, and the computer sings a
song into the tape recorder; the song is a code that represents the data.
Unfortunately, audio cassette tape recorders aren't very reliable. If you're using one of those old
Radio Shack computers, you can improve the reliability somewhat by getting Radio Shack's own
tape recorder, which is specially designed to work well with computers and automatically controls
the tape's volume. But since a tape recorder is so much slower than a disk drive, I recommend
that you not buy Radio Shack's tape recorder, and instead keep saving your pennies until someday
you can afford a disk drive. Once you've experienced the thrilling speed, convenience, and
pleasure of a disk drive, you'll never want to use a tape recorder ever again!
Commodore & Atari Old computers by Commodore and Atari (such as the Commodore Vic,
Commodore 64, Commodore 128, and Atari 800) do not attach to ordinary audio cassette tape
recorders; you must buy special cassette tape recorders sold by Commodore and Atari or - better
yet - buy a disk drive instead, if you can afford it.
Coleco The Coleco Adam computer comes with a built-in cassette tape recorder, at no extra
charge. Coleco's tape recorder is high-speed and requires specially lubricated tapes, sold by
Coleco. Since it handles just tapes that contain computer information and cannot play ordinary
musical tapes, it's called a digital cassette tape drive instead of an audio cassette recorder. But
even though Coleco's tape recorder is "high-speed" and handles computer data rather well, it's still
not nearly as fast or convenient as a disk drive.

Modern microcomputers
Most people who buy modern computers (such as the Mac, Commodore Amiga, IBM PC, and
clones) buy disk drives and don't bother using tapes at all.
If you buy a hard disk, how do you make a backup copy of that hard disk, and where do you put
the backup? You could put the backup copy onto a second hard disk or onto a pile of about 50
floppy disks. Another possibility is to put the backup copy onto a special super-fast digital
cassette tape drive that holds super-long cassette tapes that can contain backups.
Colorado The most popular such tape drives have been the Jumbo 120, the Jumbo 250, and the
Jumbo 350, all built by Colorado Memory Systems (which used to be an independent company
but is now owned by Hewlett-Packard). Those Jumbo drives work with the IBM PC and clones.
The Jumbo 120 can back up a 120-megabyte hard disk by taking the hard disk's data, compressing
it into a shorthand notation, and then storing the compressed data on a 60-megabyte tape.
Because of that scheme, the Jumbo 120 is called a 60/120M tape drive.
The Jumbo 250 can back up a 250-megabyte hard disk by compressing the hard disk's data onto a
120-megabyte tape.
The Jumbo 350 can back up a 350-megabyte hard disk by compressing the hard disk's data onto a
170-megabyte tape. The drive costs $69. The tapes cost $17 each (in quantity 5).
The newest drives from Colorado are the T1000 (which backs up an 800-megabyte hard disk by
compressing onto a 400-megabyte tape, $109 for the drive, $29 for the tape) and the T3000
(which backs up a 3.2-gigabyte hard disk by compressing onto a 1.7-gigabyte tape, $179 for the
drive, $30 for the tape).
Each of those drives is internal: it goes inside your computer. External versions cost slightly extra.
You can get those prices from New York City discounters such as Harmony (800-441-1144 or
718-692-3232) and Tri State (800-433-5199 or 212-633-2530, ask for Dave Rohinsky at
extension 233).
Alternatives Instead of buying a tape drive, the typical computerist uses a pile of floppy disks or
buys a second hard drive.
Big reels for big computers
Maxicomputers and minicomputers use big reels of tape for three purposes: to backup big disks,
to send data by mail, and to store the archives (old files that are used rarely if ever).
The reel's diameter is 101/2 inches. If you unwind the tape, you'll find the tape is half an inch wide
and almost half a mile long! The exact length is 2400 feet.
To use a reel of tape, you put the reel into a reel-to-reel tape drive, which typically costs about
$5000 and writes 1600 bytes per inch, so that the entire tape holds 43 megabytes. Super-fancy
drives, used only on the largest maxicomputers, squeeze 6250 bytes onto every inch (instead of
1600), so that they squeeze 171 megabytes onto a single reel of tape.
IBM's fanciest drive not only writes 6250 bytes per inch but also does the writing amazingly
quickly. It moves the tape at 200 inches per second, so that it transfers about 1.2 megabytes per
The motherboard and other main circuitry are enclosed in a box. The box and the circuitry inside
it are called the system unit. The box itself - without its contents - is called the case.
The computer thinks at about the same speed (number of cycles per second) as radio & TV
waves. If you put your computer next to a radio or TV, the computer's electromagnetic "thought
waves" cause static on the radio or TV. To decrease that interference, move the computer away
from the radio or TV (or change the position of the radio or TV's antenna).
The Federal Communications Commission (FCC) prohibits you from owning any device (such as
a computer) that interferes with your neighbors' radio and TV. The FCC requires all computers to
pass the FCC class A non-interference test. Any computer used in a residential area must also pass
the FCC class B non-interference test, which is harder to pass than the class A test.
To help the computer pass the class A and class B tests, manufacturers line the insides of cases
with metal that breaks up the electromagnetic waves.
When you buy a computer, ask whether it's FCC class B approved. If it's not - if it's just FCC
class A approved - you cannot legally use it in a residential area.

Surge suppressors
Instead of plugging your computer into the wall, you can plug it into a surge suppressor, which is
a special extension cord that protects your computer against surges in electrical power.
Unless you live in a neighborhood or building that has extremely poor electricity, don't bother
buying a surge suppressor. The typical computer has some surge protection built into it already.
If you're worried about thunderstorms sending surges to your computer, just unplug your
computer during storms! If your air conditioner or electric heater consumes too much electricity
and causes a brownout (so your computer acts unreliably), use a plain extension cord to plug your
computer into a different outlet, so that the computer's not on the same circuit as the
power-hungry appliance.
During the summer, most computer errors are caused by temperatures over 95ψ, not by power

Buyer's guide: other hardware

Buyer's guide: other hardware

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