% Hardware chapter
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\documentstyle[twoside,12pt]{article} 
\usepackage{htx}
\me{Andy Harris, aharris@klingon.cs.iupui.edu} 
%author(s) names and/or email address

\begin{document}

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\docheader{Introduction to Computing}
{5}   % module number
{Understanding the Hardware}  % module name

\begin{goallist}

\item Recognize the difference between hardware and software
\item Determine relationship between bit measuring terms (bit, byte,
      K, Meg)
\item  Be able to decipher the code words in a computer advertisement
\item  Distinguish between input and output devices
\item  Identify the major hardware components in a desktop computing system


\end{goallist}

\begin{prereqs}
\item Knowledge of the STAIR problem solving process
\item Understanding of essentials of computing


\end{prereqs}

% Page 2 ...

\section{Deciphering an Ad}
One of the things that intimidates people about computing technology
is the horribly complex and obscure jargon that surrounds the field.
Some of these terms are vague and complicated, but some are really
useful.  Today, we are going to discuss those computer terms that you
would need to understand if you wanted to go buy a computer.  The
advertisements in a typical computer magazine appear to be written in
some obscure dialect of Serbo-Croation or something.  Here is a
typical example:

\begin{itemize}

  \item 120MHz Pentium Processor
  \item 16MB DRAM
  \item 850MB 10ms IDE HD
  \item 1MB DRAM 64-bit PCI Graphics Accelerator Video Card
  \item 8X CD-ROM
  \item 3.5'' FD
  \item 16 bit Soundblaster Compat
  \item 28.8 Fax Modem
  \item 15 inch Monitor, 15.28 dp
  \item 7-bay mini-tower case
\end{itemize}


Believe it or not, this is not too difficult to decipher.  By the end
of this section, you will have some clue about what kind of a computer
that is.

\section{Hardware and Software}
As you remember from last time, a computer is considered a universal
information manipulator.  It is universal because it can do many
different kinds of things, depending on which instructions are stored
in memory.  This list of instructions is called a program.  Programs
are also referred to as software.  So far, we have been pretty
theoretical about how computers work, but we know that besides the
software, they do have a physical entity.  The physical pieces you can
see are referred to as hardware.  A computer system is a combination
of both hardware and software.


\subsection[s]{Hardware}
You are already familiar with the term hardware, as in the hardware
store.  Hardware, in a more general sense, refers to anything with a
physical prescense.  Any part of a computer system that can be
physically touched and handled (even if you might never actually touch
it) is considered hardware.  Most of the machines we are used to are
mainly hardware.  A CD player is hardware, as is the CD.  All the
stuff in the ad above was hardware.


\subsection[s]{Software}
One of the things that makes computers so unique is their ability to
deal with software.  Software is the more esoteric stuff that
computers work with.  Software is the information and instructions
that give computers the 'universal' feel.  You have dealt with
something like software, even if you have not used a computer very
much.  Think of this example:

Denise goes shopping for a music CD.  She sees a CD she really wants
to buy.  It costs \$17.99!  She looks around a little more, and notices
that there are other CDs around that only cost \$4.00.  A friend has
told her that it only costs a couple of dollars to create a CD.  She
wonders why some CDs are more expensive than others.  All CDs are
physically pretty much the same.

Of course, Denise does know why the CD she wants is more expensive.
All the disks cost pretty much the same to manufacture, and they are
physically very similar.  The only relevant difference between the
\$4.00 CD and the \$17.99 one is the CONTENTS of the disk.  The music on
the disk is not something tangible.  She cannot touch it or see it,
but she knows that it is there, and she is willing to pay for it.  The
real value she is searching for is not the mylar and plastic, but the
INFORMATION that the physical entity stores.  Information and
instructions are software.  They are what give the computer such
power.  Hardware is the physical stuff that makes software possible.

\subsection[s]{Firmware}
Just for your information, there is something called firmware.  As you
may have guessed, it is somewhere between hardware and software.
(mayonnaise consistency?)  It really doesn't come up that often, but
it does exist.

\section{The Bit and its offspring...}
Computers have a number of measurable properties.  They vary greatly
in speed, capacity, and power. To discuss these differences, we need
some new units of measure.

\subsection[s]{The Bit}
The basic unit of measure in a computer system is the bit.  A bit is
one on/off switch.  It is the smallest unit in computing, and is the
foundation for for everything else.  Since bits are binary (remember
what that means?) they have widespread implications for how
information is stored and measured.  The binary numbering system and
its related systems (base 8 and 16) are used to measure just about
everything in a computer system.  This explains why the numbers used
to measure computers might seem a little odd to us.  We are used to
thinking in base 10, but the computer will interpret everything in
base 2.  A number like 255 is not very pretty in base 10, but in
binary notation it is 11111111, which is a  clean, lovely number.  You
will often run across numbers like 8, 16, 32, and 64.  These numbers
are powers of two, so they are nice and clean in binary notation.
Just keep this in mind during our discussions today.


\subsection[s]{The Byte}
While the bit is undoubtedly important, it can only hold two possible
values, 1 and 0. In order to represent anything more complex than the
simplest binary values, we have to combine bits. Eight bits are
combined into a unit called a {\bf byte.} Each bit represents
one digit of binary notation. If we put eight of these binary digits
together we can represent any number from 0 to 255. Zero would be
represented by 00000000 in binary, or all eight bits turned off. If
all the bits were on, the largest possible value would be 11111111
binary, which translates to 255 decimal. This is a large enough value
to be useful. For example, all the values of the ASCII character set
can be represented in one byte.  (This is not a coincidence!)

\begin{quest}
I recently came across an Internet message which claimed that much of
the Internet was a conspiracy by big business.  One of the author's
more interesting theories was that a certain kind of address
information called the ip address was limited to a maximum value of
255 rather than 999 deliberately to reduce the supply of addresses and
thus make them more valuable.  It is true that these addresses have a
maximum value of 255.  Can you think of another reason this could be
the case?  

\end{quest}

\begin{quest}
Many computer monitors are capable of displaying 256 colors at a time.
Why this number?

Why isn't it 255?
\end{quest}

\begin{quest}
If you had a document that was 500 bytes long and saved in ASCII
format, about how many characters long would the document be?
\end{quest}


\subsection[s]{The Kilobyte}
Although bytes are much more useful for keeping track of memory than
bits, they are still a little small for measuring larger entities, like
disk space, file size, and memory capabilities.  Some early floppy
disks, for example, could hold  368,640 bytes of information.  The
numbers were getting too big for humans to handle easily.  Computer
scientists used kilobytes to measure these larger quantities.  No
doubt you are familiar with the metric system, and you know that a
kilo represents a thousand.  E.G. a kilogram = 1000 grams, a kilometer
= 1000 meters.  In computing, a kilobyte {\bf does not} mean exactly
one thousand.  A kilobyte is 1024 bytes.

Why?
It all goes back to the binary system.  We like the number 1000
because it is easy to work with in base 10.  Computers do not
naturally work in base 10, but in base 2.  1000 decimal becomes
1111101000 in binary.  This is obviously not a convenient number in
binary.  Fortunately, the binary value 10000000000 is very easy to
work with in binary, and it works out to 1024 in decimal.  This is
close enough to 1000 decimal that we refer to 1024 bytes as a
kilobyte.  Kilobyte is often abbreviated K.  The 368,640 byte disk we
referred to before would be called a 360 K disk.

\begin{quest}
A later kind of floppy disk was capable of handling 720K.  How many
bytes is that?

How many bits is it?
\end{quest}


\subsection[s]{The Megabyte}

The kilobyte is a more convenient unit of measure than the byte, but
rapid advances in computing technology made it difficult to work with
as well.  Computer manufacturers began developing equipment with
capacities of many thousands of kilobytes.  Once again, computer
scientists used a variation of the metric system to save the day.  A
thousand kilobytes is referred to as a megabyte.  Modern floppy drives
often have a capacity of roughly 1,440 K.  This value is often
referred to as 1.44 M.  The term Megabyte is often abbreviated Meg, M,
or Mb.  Disk drives and memory capacity are often measured in
megabytes.

\subsection[s]{The Gigabyte}

Computer technology continues to increase capacity at an amazing rate.
There are now disk drives available which are measured in gigabytes.
A gigabyte is 1000 megabytes.

\section{The CPU}

The heart of a computer is a device referred to as the Central
Processing Unit (Often abbreviated CPU).  The CPU is the physical
device where all the fancy processing we talked about in the
essentials of computing happens.  Every other device attached to a
computer system eventually sends information to or receives
information from the CPU.  The basic kinds of instructions (like the
add, store, jump instructions we played with earlier) are built into
the CPU.  The characteristics of the CPU determine what kind of
computer you have.
  
\subsection[s] {Processor}

There are two major types of processors being used in home computers
today.  Macintosh computers are based on a family of CPUs created by
Motorola.  IBM compatibles are based on a family of CPUs made by
Intel.  These different CPU flavors have completely different sets of
instructions that they read at the simplest level.  A program written
to run on a computer based on the Motorola CPU will not run on a
computer that uses an Intel chip.  Each of these families of
processors has a number of models available.  The latest processor is
almost always much faster than its predecessors, and more expensive.
In the Intel world, for example, we have had the 8086, the 80286, the
80386, the 80486, and the 80586. Computer sales types refer to these
processors as: 8086, '286, '386, '486, and Pentium processors)

Each of these processors has been roughly twice the speed of its
immediate predecessor.

\subsection[s] {Speed}

A cpu also has a speed rating based on millions of cycles a second.
One million cycles in a second is referred to as a megahertz.
Megahertz is usually abbreviated Mhz.  In general, the larger the
megahertz rating, the faster the processor will be.  A 100 Mhz Pentium
will be faster than a 66 Mhz Pentium.  This rating system is only
accurate when you are comparing computers with the same type and
generation of cpu.  A 25 Mhz 486 is faster than a 33Mhz 386(!)

\subsection[s]{Choosing a CPU}

Since the CPU determines everything else about a computer, it is
obviously pretty important.  It would be possible to buy a computer
and then learn that all the programs you want are written for
different CPUs.  To avoid this situation, you need to carefully think
about what you want from your computer.  Visit friends who have
computers, look around in the stores, and think about what you really
want your computer to do.  Go to a software store and look at the
programs on the shelves.  They will almost always have a little
sticker on the box explaining what kind of processor you need to run
that particular program.  If you see ten programs that you might
purchase some day, and eight of them require a 486 or higher chip, an
IBM compatible with a 486 or Pentium chip is probably the machine for
you.  If you really like the interface on Macintosh computers, and
don't want to learn anything else, that might be your computer.  After
you have chosen the type of cpu, you will need to choose a speed.  The
faster chips are more expensive.  Again, look at the software you will
want to run.  If you can get by with a computer running at 33Mhz, why
buy anything faster?  Certainly you have more options with a faster
cpu, but think about what you will use the computer for.  If you will
be playing games or doing other graphics - intensive work, a high
speed CPU is very important.  If most of your time is spent with word
processing, the speed is not such a factor.  While using word
processing programs, even the slowest computers spend most of their
time sitting and waiting for the user to type in a character.  A very
slow computer by today's standards might cycle 33 million times a
second.  How fast do you type?  A general guideline might be to buy as
fast a CPU as you can afford, but to worry a little less about speed
if you are just using your computer for word processing.

\section{Input Devices}

The CPU is a very powerful thing, but all it does is work with
information.  It needs to get this information from other kinds of
devices.  Any component of a computer system that sends information
into the CPU is called an input device.

\subsection[s]{Read Only Memory (ROM)}

Memory is like the banks of switches we have been thinking about that
simply contain 1/0 binary patterns.  Read Only Memory (abbreviated
ROM) is a special kind of memory that cannot be changed.  The most
basic instructions for the CPU are built in to the ROM at the factory.
To the end user, there really is very little to worry about regarding
ROM.  The amount of ROM in your computer doesn't really matter to you.
All your programs and information will go into another kind of memory
that we will learn about soon.

\subsection[s]{Keyboard}

The keyboard is probably the easiest kind of input device to
understand.  When the user presses a key, a code is sent to the cpu,
which translates the code into some sort of storage format (usually
ASCII.)  There is generally no way for the cpu to send information
back to the keyboard, so it is an input only device.  Usually, you buy
a keyboard as part of a computer system, but there may be a reason you
want a specialized model.  Certain keyboards are designed to be more
ergonomically safe to prevent Carpal-Tunnel Syndrome (a common malady
of those who spend all day at keyboards.)

\subsection[s]{Mouse}
Many modern computers rely heavily on the mouse.  This is a small
object, usually with a roller ball on the bottom, that can be dragged
along the desktop.  Mice usually have one or more buttons on them that
can be activated with the hand controlling the mouse.  As the mouse is
moved on the desk, a pointer moves on the screen.  This mouse pointer
is analogous to the user's hand.  Many find this a more natural way of
controlling the computer than typing on a keyboard.  There are a
number of ``mouse substitutes'' available, but they all basically work
in the same way.  Laptop computers often have a small ball embedded in
the keyboard that can be rolled so the mouse can be activated even
when the computer is being held on the user's lap.

\subsection[s]{CD-ROM}
The same kinds of technology that enable us to store music digitally
on compact disks allows us to store other kinds of information on the
same medium.  Compact Disks essentially store numbers.  They are
inexpensive to create, and can hold large amounts of information.
(600 Mb) CD-ROMs are frequently used to sell software which has become
too large to fit on floppy disks.  Unfortunately, a CD - ROM cannot be
written to with typical home technology.  The ROM part of CD-ROM
refers to this characteristic.  A CD - ROM is an input device because
it can send information to the CPU, but the CPU cannot send
information to it.

CD Drives are measured in comparison to the speed of music CDs.  An
audio CD always runs at a constant speed.  A 2X CD drive is twice the
speed of an audio CD player.  6X and 8x drives are available at this
writing.  Even these drives are not as fast as typical hard drives.

Erasable CD drives are becoming popular, because they hold as much
information as a regular CD, but the user can store things to them as
well as reading from them.  Such devices will probably be much more
prevelant as their price comes down and reliability improves.

\subsection[s]{Other Input-Only devices}

There are other devices available for input, but they tend to be
specialty devices.  Some examples are:

\begin{itemize}
  \item Touch - sensitive screens for mall kiosks.
  \item Adaptive keyboards for individuals with physical disabilities
  \item Infrared mice for a mouse without cords
  \item Special presentation devices that allow a speaker to send input to
  the computer while delivering a presentation away from the keyboard.
\end{itemize}


\section{Output Devices}
Another category of devices is designed primarily for output.  These
devices get information from the cpu, and send it somewhere.

\subsection[s]{Printer}
Printers take information from the CPU and transfer it to paper.
There are a number of different printer technologies available.

\begin{definition}

\item [\bf Dot Matrix]
Dot Matrix printers are inexpensive and reliable, but they are loud
and slow.  They do not have nearly the print quality of some of the
other types of printers.  

\item [\bf Ink Jet] Ink Jet printers squirt
small streams of ink onto the paper.  They tend to be slightly more
expensive than dot matrix printers, but the quiet operation and
improved print quality make them very popular with buyers of home
computers.  Some ink jet printers can make color prints.  These can be
very entertaining, but the ink becomes expensive.

\item [\bf Laser Printers]
Laser Printers use a combination of laser and copying technology to
make very clear copies.  Laser printers tend to make clearer copies
than the other types of printers, and operate much more quickly, but
they can be quite expensive to purchase and maintain.  
\end{definition}

Many people try to save money on a printer purchase and are
disappointed.  If the main reason you will use your computer is to
type letters, remember that the people you write to will not see your
monitor.  What they will see is only what comes out of your printer.
If printed documents are an important part of what you will use a
computer for, consider a higher quality printer.  Ink Jets are
probably most appropriate for home use, and laser printers are more
popular in an office setting.  A dot matrix machine is fine for test
printing or use on a kid's computer, but you will be disappointed with
the results if you try to use it for business correspondence.

Before buying an ink jet, find out how much the ink cartridges cost,
and how long they tend to last.  With a laser printer, be sure to
check on the cost of toner cartridges.

\subsection{Monitors}
The monitor is the part of the system that you look at most of the
time.  Monitors resemble televisions.  Most computer monitors use the
same technology as televisions, but with much higher resolution.
Often the monitor will come packaged with a computer system, but you
may wish to upgrade.

\subsubsection[s]{Size}
The size of a monitor can make a big impact.  You might get a headache
squinting at a screen that is too small.  The size of a monitor is
measured in diagonal inches.  a 15 inch monitor is 15 inches
diagonally from corner to corner of the screen.

\subsubsection[s]{Dot Pitch and DPI}
Monitors are also measured by their precision.  There are two main
measures, Dot Pitch, and DPI.  

Dot pitch is a measure of the size of each tiny dot the monitor can
display.  The smaller each dot is, the nicer the picture will look,
but the more expensive the monitor will be.  When discussing Dot
Pitch, SMALLER IS BETTER!!

DPI stands for Dots Per Inch.  As you can guess, the smaller the dot
pitch rating for a monitor is, the more of those tiny dots you could
squeeze into a square inch.  If you are considering DPI, LARGER IS
BETTER.  

Computer sales people are not above taking advantage of this
confusion.  

\subsubsection[s]{Video Controller Card}
Dealing with graphics takes a lot of work.  Modern computers usually
have a separate computer built in just to help with controlling the
monitor.  This little computer has its own cpu and memory!  The power
and speed of this little computer, as well as its memory capacity,
have a huge effect on how graphics are drawn to your screen.  This
little computer is referred to as a graphics controller card.  The
most common cards now are called SVGA.  (You really don't need to know
what it stands for but here goes: Super Video Graphics Array).  Of
course it gets way more complicated than this, but all you have to
know is that there are fancier cards that do more and cost more, but
you may not need the fanciest one out there for your first computer.

\section{Devices that do Input AND Output}
Some of the most important parts of the computer system can do both
input and output.  These devices have a sort of 'two - way - street'
relationship with the CPU.  Information can flow back and forth
between them and the CPU.

\subsection{Random Access Memory (RAM)}
RAM is perhaps the most important of the input/output devices.  When
we talk about computer memory, we are mainly talking about RAM.  In
this class, when we think about the banks of light switches that can
be manipulated, we are thinking of RAM memory.  The term Random Access
is pretty unfortunate.  There is nothing random about how memory is
accessed.  The program running will determine what is in memory.  (of
course, the program itself is in memory too!) RAM can be read from by
the CPU.  This means that the CPU can 'look' at any address in RAM and
get the contents of that address.  It can also be written to by the
CPU, meaning that the CPU can change the value of memory cells on the
fly.  

One VERY important aspect of RAM memory is that it requires power.
RAM can only hold values while power is going through it.  If the
power is interrupted, the RAM will lose ALL the values in it.  This is
why it is so important to save your work frequently when working on a
computer.  RAM memory is volatile.  When the room you are working on
is hit by a tsunami and the power goes out of your computer, you lose
everything that was in RAM.  This could be bad.  The answer is to make
copies of RAM, and place these copies on other kinds of media.  That's
what disk drives are for.  (see below...)


The amount of RAM in your computer is obviously a pretty important
factor.  The more memory you have, the more 'room' there is in your
computer for information and programs.  Modern programs have gotten
HUGE, and the kinds of information you can work with have gotten much
larger.  Some early home computers had 4 or 16 K of RAM.  The original
IBM PC had 640 K of RAM. In its day, this was thought of as an
extravagant amount of memory that would never be fully used.  Modern 
computers with less than 16 Megabytes (16,000 K) are considered a bit
lame.  (pun completely intended.)  Older computers can be quite happy
with much less RAM, but they will not be able to run the newer programs.

If you are buying or upgrading a computer, you should seriously
consider as much RAM as you can afford.  There is probably no more
cost-effective upgrade than RAM.  

If you find that you need more memory, It is relatively cheap and easy
to do a memory upgrade.  Note that not all types of RAM are
interchangeable.  Look in the book that came with your computer for
specifically which type of RAM you need when you are ready to upgrade.

Most of the time when we speak of memory, we are only thinking of RAM.
In computer advertising, RAM is sometimes referred to as DRAM for
Dynamic RAM

\subsection{Disk Drives}
Disk drives are special devices that allow us to make copies of parts
of RAM and store them magnetically.  If RAM memory is electronic,
think of disk drives as a special kind of magnetic memory.  When you
save something to a disk, the electronic impulses in RAM are copied
and stored to the disk as a series of magnetic impulses.  All a disk
drive does is translate electronic impulses and magnetic impulses back
and forth.  

Disk drives are handy because magnetic impulses are more permanent
than electronic ones.  The disk drive does not require electricity to
keep values in memory, so if you store something to a disk, the
information will be there when the tidal wave knocks the power out to
your computer.  (Assuming, of course, that the disk stayed dry and
clean)  Disks are sometimes thought of as secondary storage for this
reason.  

There are a number of different kinds of disks.  We will discuss a
couple of main types: 

\subsubsection[s]{Floppy Drives}
A floppy drive is a machine that is designed to read floppy disks.
Floppy disks are the removable devices that you stick in slots in the
front of the machine. I know, they look square, not disk-shaped, and
they don't look floppy at all, but they are indeed floppy disks.
Floppy disks come in hard plastic cases to make them a little more
sturdy and easier to handle, but inside the plastic case, there is an
actual disk.  It is made of a plastic-like substance called mylar
which really is floppy.  Floppy disks come in two main sizes;  5 1/4
inch, and 3 1/2 inch.  The 5 1/4 disks are becoming obsolete, but you
still see them from time to time.  The 3 1/2 inch disks, although
physically smaller, can usually hold more information!  

There are different flavors of floppy disks.  In a modern computer,
the only kind of floppy you need to purchase is High Density 1.44 MB.
As you can guess, they hold 1.44 MegaBytes of information, which is a
pretty good amount.  (You could hold several hundred pages of text or
about a dozen full color pictures on a 1.44 MB disk) This type of disk
may carry some other markings as well, such as DSHD or HD.  The HD is
the important part.  That tells you it can handle 1.44 MB.  If you
have an older computer, you may find that it needs a different type or
size of disks.  Check your documentation to be sure.


\subsubsection[s]{Hard Drives}
A hard drive is a special disk that is usually mounted permanently
inside your computer's cabinet.  You rarely see the hard drive, and
almost never take it out.  Hard drives are made of different material
than floppies, and they are physically hard (although if you touched
the actual hard surface, you would destroy it!) They spin much more
quickly than floppies, and require much more precision.  They are
sealed inside a special case, and that is sealed inside the computer
case.  A hard drive has a much larger capacity than a floppy, and is
much faster at saving and retrieving information.  Modern computers
frequently have hard drives with 500 MB or more of capacity.  As this
capacity grows, people are beginning to measure it in terms of gigabytes.
Software programs are always becoming larger and taking more room on
hard drives.  It never takes long to completely fill up the capacity
of a drive.  If you can afford a large drive when you buy the
computer, you won't be sorry, but you can usually add another drive or
upgrade later.

\subsubsection[s]{Fancier kinds of drives}
There are a number of other types of drives you may encounter when
buying or upgrading a computer.  You may encounter such things as
Bernoulli tape drives, WORM (write once, read many) drives, optical
floppies, and removable hard drives.  All these things are really
cool, but you may want to stick with the basics until you are a little
more comfortable with the technology.  Any computer system ought to
have at least one 3.5 inch floppy drive, as large a hard drive as
possible, and a CD-ROM drive.

\subsubsection[s]{Drive Controller Cards}
Most computers come with a small card installed that helps control all
your disk drives.  It is called the Drive Controller Card. (Wow, those
computer scientists have some kind of imagination, huh?)  You really
don't need to worry about this device very much.  There are two major
kinds, IDE and SCSI.  The only time you will ever care about this is
when you buy a hard drive.  Just know that the terms IDE and SCSI
(pronounced 'scuzzie') are terms that describe the drive controller card.

\subsection{Network Card}
In a home computer, you will generally not have a network card, but
these devices are very common for computers in office settings.  A
network card is a special card which allows your computer to talk to
other computers that are physically attached via cables.  Depending on
how the network is set up, you can send messages from computer to
computer, run programs that are stored on different computers, and
share devices like hard drives and printers.  In many offices, the
network also gives you access to the Internet.  Network connections
are generally faster than modem connections.

\subsection[s]{Modem}
Modems were once thought of as somewhat extravagant, but with the
advent of the Internet, they are becoming a necessity for home
computers.  They allow you to connect your computer to the Internet or
other computer systems through a telephone connection.  The term Modem
stands for Modulator / Demodulator.  It is a device that converts back
and forth from the digital signals that computers understand to analog
signals (sounds) that can be transferred over telephone lines.  Modems
can be internal or external.  The external ones have their own little
case and power supply, and are generally a little more expensive than
the internal ones, which are little cards that fit inside the
computer.  Modems are rated by their transmission speed, which is
measured in BAUD (Bits of Audio Data / Second).  If you want to do any
Internet connections, you need a baud rate of 1440 BAUD (also
sometimes called 14400 BPS or 14.4 KBPS) You can also purchase faster
modems, but they are of course more expensive.  In the near future,
something will happen in this arena.  It is likely that we will be
switching to a completely new kind of communication technology for
home computers, but nobody knows exactly what that will be just yet.
Some modems also include faxing and voice mail capabilities.  These
features can be very convenient for people with home offices.

\subsection[s]{Sound Card}
Sound cards are another peripheral device that was once thought to be
extravagant, but is now pretty much standard equipment on any new
machine.  A sound card is a device which enables the computer to
handle sounds (duh!).  It can handle sounds in two major ways.  It can
create sound effects entirely through programming, or it can record
sounds through a standard microphone.  Sound cards are attached to
speakers which recreate the sound.  Obviously, sound cards are a big
boost to computer game players, but they are frequently being used for
more serious pursuits as well.  People can attach voice annotations to
documents they have written, musicians can test and modify a
composition with a computer, and people with visual disabilities can
have screens of text read to them. The basic sound card is referred to
as an 8-bit sound card, because it processes 8 bits of information at
a time.  You can now find 16-bit, and even 32-bit sound cards if you
are willing to pay for them.  As always, it depends on what you want
your computer to do for you.

\section{Buying a computer}
All those details are very confusing.  Computer sales people know
this, and take advantage of it.  If you generally followed most of the
things we've talked about in this chapter, but you still don't know
IDE from SCSI, don't worry.  You still probably know nearly as much as
the salesperson you are dealing with. Much of the time, salespeople
deliberately go into heavy jargon-speak.  Don't let that intimidate
you!  You know the basics of what a computer should have, and you
should know what you want.  You are the one with the money, and they
have to please you.  Here are some guidelines.

Decide if you are ready for a computer.
Maybe you aren't yet.  That's OK.  Wait until you are.

Decide HONESTLY what you think you will do with a computer.  Everyone
says ``Oh, I'm mainly going to write letters and balance my
checkbook.''  Malarky.  If you want to be able to play games, surf the
Internet, and run that really cool game you saw advertised last week,
you don't have to admit that to anyone else, but admit it to yourself.
If all you are really going to do with your computer is basic
applications, you don't need much of a computer.  If you want to run
the newest, coolest applications, you need a more elaborate setup that
will cost you more money.  The best way to find out the right machine
for you is to go to a software store and look at the shelves.  Pretend
you were given enough money to buy any 5 programs in the store.  Look
at the boxes the programs come in, and you will see a section
somewhere that describes the minimum equipment requirements for that
program. After you have compared a few such programs, you will begin
to see what kind of computer you really want to have.  If all the
programs you want require a 486 or Pentium, you will probably be
disappointed with a 386 or a Macintosh.  It might be that all the
programs you want will run on a 486, but you need a CD-ROM.  That
should guide you in your decision process as well.

Think also about the ease of use factor.  As we explore operating
systems in this class, think about which one you like best.  How
important is that to you.  Many people are sold on Macintosh simply
because they love the operating system, although there is much less
software available for the Macs.  

Finally, think about compatibility.  This is not nearly as big an
issue as it used to be, but it can still be a factor.  For example, if
you are a teacher, all the work you do at school is on a Mac, and
you want to be able to work at home as well, a Macintosh similar to
the one at work makes sense.  Likewise, if you are an accountant, and
you want a copy of Peachtree at home, you will probably need a PC.
Remember that the Internet is making compatibility less of an issue,
but it still is a factor.

Think about how much money you have to spend.  Since the beginning of
the home computer boon, the top - of - the line home computer system
has always cost about \$3000.  (Of course the machine you spent \$3000
on in 1983 is worth about a dollar and a half today, but that is
irrelevant).  If you have \$3000 sitting around, your decisions are
easy.  Most of us have to compromise somewhere.

Any computer system you buy today will be obsolete in a few months.
You can't sit there waiting for the market to settle down, because it
isn't going to happen.  Accept the fact that you may not have the best
machine out there, and get the best machine for you you can afford.  

Consider an older or used computer.  If you don't mind using an older
operating system and programs, they can serve you well.  Systems that
cost several thousand dollars a few years ago can now be found quite
cheaply.  It will be harder to find programs for them, but once you
do, you can suffice quite nicely.  Used computers can sometimes be
found at used computer stores, and sometimes offices sell older but
still very serviceable computers to their employees at very reasonable
rates.  You may also want to check the want ads.  You might find a
very good deal on a computer fully stocked with software and
peripherals.  These older cheaper computers are ideal for college
students and others with enforced poverty levels.

Think about whether you want a laptop.
Laptop computers are those amazing computers which are just as
powerful as their desktop cousins, but small enough to fit in a
briefcase.  The obvious advantage of a laptop is portability and
convenience.  With batteries, a laptop can be taken nearly anywhere.
If you are willing to pay for it, you can find a laptop computer as
powerful as nearly any desktop anywhere.

There are two main problems with laptops.  In order to fit such power
in such a small space, the designers of laptops often have to squeeze
things together in unusual creative ways.  This makes laptops
generally more expensive than desktops, and also makes them more
difficult to upgrade.  On a desktop computer, you can simply remove
the top, take out a card, and replace it with a new one.  Laptops are
generally made so the user cannot take them apart and cannot do many
upgrades at all.  A standard called PCMIA improves this situation, but
PCMIA - based devices for laptops are much more expensive than the
same device designed for a desktop machine.

Comparison shopping is important.  For one thing, you can use the
information you learn on earlier searches to make you sound smarter
later on.  You might start by finding a computer you like, then
writing down the specifications for it.  The next store you go to, you
don't have to say ``Gosh, I want a computer-thingy.''  Instead, you
can say ``I'm looking for a Pentium 100 or better with 15Mb of RAM and
at least a 500 Mb Hard drive.''  Even if you don't find the computer
there, the sales person is far more likely to take you seriously and
meet your needs.  

\section{Deciphering the ad}
Remember the advertisement from the beginning of this chapter?  Let's
look at it again:

\begin{description}
\item[\bf 120MHz Pentium Processor]
This computer has a relatively new processor, it is IBM compatible, 
and it runs at 120 million cycles a second, which is pretty fast.

\item[\bf 16MB DRAM]
It has 16 megabytes of RAM,  which is plenty for now, but we may need
more later.

\item[\bf 850MB 10ms IDE HD]
It has a hard drive that can store 850 megabytes of information.
Again, that's pretty big, but we may still need more space later.


\item[\bf 1MB DRAM 64-bit PCI Graphics Accelerator Video Card]
It has a nice video card with 1 megabyte of its own memory.

\item[\bf 8X CD-ROM]
It has a CD drive that can run 8 times faster than audio CDs.

\item[\bf 3.5'' FD]
It has a standard floppy disk drive.  Boring but still important.

\item[\bf 16 bit Soundblaster Compat]
It has a standard sound card.

\item[\bf 28.8 Fax Modem]
It has a built in modem that is pretty fast.  The modem can also be
used to send and receive faxes

\item[\bf 15 inch Monitor, 15.28 dp]
It has a monitor that is 17 inches in diagonal, and the dot pitch
value of the monitor is 15.28  

\item[\bf 7-bay mini-tower case]
It has room for up to 7 more devices, although some of these slots are
surely being used by the modem, drive controller card, and so on...
\end{description}

\section{Laboratory Assignment}  % comment out if not applicable
\begin{itemize}
\item Your teacher will provide for you either an opened computer
system or a picture of a typical system.  Identify and label at least
the following components of that system:
\begin{itemize}
\item The CPU
\item RAM Memory
\item The Motherboard
\item The expansion slots
\item The Hard drive
\item A Floppy drive
\item The Keyboard
\item The mouse
\item The monitor
\item The device / driver controller card
\item The power supply
\item Serial / Parallel ports
\item Any other special cards or devices attached to the machine
\end{itemize}

\item 'Practice' purchasing a computer.  Decide on a reasonable
budget.  Determine what kinds of things you want to be able to do with
your computer.  Which programs will you need to be able to run?  Write
down the specifications of at least three kinds of software you would
like to be able to run on your new computer.  Go to computer stores
and magazines, and find a computer that will run that particular
software.  How much will it cost?  Will it do what you want?  Use a
word processor to write out answers to all the above questions with a
narrative of the shopping experience.

\item Decipher a computer advertisement.  Your instructor will give
you a computer advertisement, or you can seek one out from a computer
store or a magazine.  Write down all the 'code words' for that
computer.  Translate each code phrase into its meaning in English.  If
you don't know a particular phrase, make an informed guess (try
researching before making a completely blind guess).  Use a word
processor to write out this process in a table form and turn it into
your teacher.
\end{itemize}



\begin{vocab}   % vocabulary/main concepts list
\begin{definition}
\item[\bf Hardware]
The physical part of the computer system you can see and touch

\item[\bf Software]
The data, programs, and other esoteric parts of the system that do not have a physical presence

\item[\bf Bit]
One on/off unit.  The basic unit in a computer system.  The value of a
bit can be 0 or 1.

\item[\bf Byte]
Eight bits.  A byte is large enough to hold one character in ASCII

\item[\bf Kilobyte]
1024 bytes.  Used to measure memory and disk capacity.  Often
abbreviated K or Kb.

\item[\bf Megabyte]
1000 Kilobytes.  Used to measure memory and disk capacity.  Often
abbreviated Meg or Mb.

\item[\bf Gigabyte]
1000 Megabytes.  Used to measure large disk drives.  Usually
abbreviated Gig.

\item[\bf CPU]
Central Processing Unit.  The 'heart' of the computer.  The
characteristics of the CPU have profound effects on the performance of
the entire system.  CPUs are measured by their chip name and speed.

\item[\bf Intel]
The manufacturer of IBM - Compatible CPUs.  The modern Intel chips
are: (from oldest to newest) '386, '486, Pentium.

\item[\bf Motorola]
The manufacturer of Apple Macintosh CPUs.  The current Motorola CPU
is the PowerPC chip.

\item[\bf Megahertz]
A unit of measure for processing speed.  One Megahertz is one million
instruction cycles per second.  Megahertz is often abbreviated Mhz.

\item[\bf Input]
A device or process that goes into the CPU from somewhere else.

\item[\bf Output]
A device or process that goes from the CPU to someplace else.

\item[\bf ROM]
Read Only Memory.  A special type of memory that has information
stored on in from the factory.  The user cannot change the information
in ROM.

\item[\bf Carpal-Tunnel Syndrome]
One of a number of repetitive stress disorders that can be caused by
frequent typing.  Careful posture and hand positioning, as well as
some adaptive devices like wrist pads and special keyboards can
minimize the effects of this type of problem.

\item[\bf CD-ROM]
A drive / disk combination that allows the user to retrieve
information stored on compact disks.  Most Current CD drives do not allow
the user to write on them, but such technology is becoming more
popular and less expensive.

\item[\bf Impact Printer]
A type of printer that operates by striking the paper with an inked
ribbon.  Reliable and inexpensive, but slow and loud, and with limited
resolution.

\item[\bf Dot-Matrix Printer]
The most common type of impact printer.

\item[\bf Laser Printer]
A device that combines printing and copying technology.  Relatively
expensive to operate, but fast and very high resolution.

\item[\bf Ink Jet Printer]
A printer that operates by squirting precise jets of ink onto the
paper.  They are relatively inexpensive, and have nearly as much
quality as Laser Printers, but they are slower.

\item[\bf Dot Pitch]
A unit of measurement describing the resolution of a monitor.  A small
dot pitch number means a clearer monitor.

\item[\bf DPI]
Dots Per Inch.  Another unit of measure for the resolution of a
monitor.  A large DPI value means a higher quality monitor.

\item[\bf VGA, SVGA]
Types of video controller cards.  Almost all modern Intel - based
computers handle some form of SVGA (Super Video Graphics Array).

\item[\bf RAM]
Random Access Memory.  This is the memory that can be manipulated by
the user and programs.  The amount of RAM in a computer is an
important performance factor.  Usually measured in MB.  Sometimes also
referred to as DRAM.

\item[\bf Floppy Disk]
A portable storage medium which can be removed from the computer.
Floppy disks currently come in 3 1/2'' and 5 1/4'' sizes. Even though
a 3 1/2'' disk appears to be hard, it is NOT a hard drive.

\item[\bf Floppy Drive]
The machine installed in the computer console which reads and writes
from floppy disks.  Usually measured in Kb or Mb.

\item[\bf Hard Drive]
A permanently installed drive with a much larger capacity than floppy
drives.  Usually measured in Mb or Gig.

\item[\bf IDE, SCSI]
Types of drive controller cards.  Most PCs come with IDE controllers.

\item[\bf Network Card]
A device that allows you to attach your computer to other computers in
the same general vicinity.

\item[\bf Modem]
A device that allows you to attach your computer to remote computers
through analog telephone lines.  Measured in Baud or Kilobaud.

\item[\bf Sound Card]
A device which enables the computer to generate or duplicate sounds.
Usually attached to speakers and a microphone.  

\item[\bf Baud]
Bits of audio data/ second.  Modern modems are usually 14,400 or
28,800 baud.  Sometimes also referred to as BPS (Bits Per Second.)

\item[\bf PCMIA]
A standard for connecting external devices to laptop computers.

\end{definition}

\end{vocab}

\section{Summary}
The terminology of computing hardware can be staggering.  The
technology changes so quickly that it is difficult to describe
computing equipment.  This has contributed to the fears of first -
time computer buyers.  

Fortunately, there are some key concepts that can be used to help
decipher all these frightening terms.  Knowledge of the major units of
measure and the major types of computing hardware will make you a
smarter computer shopper.  

When buying a computer system, it is critical to carefully evaluate
what you want to do with your system, and which software packages you
want to run.  With some care, you can purchase a system that meets
your needs without spending too much money.

\anslist{abhwans}

\end{document}

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