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^C^1Introduction to Telecommunications
^Cby
^CDaniel Tobias

   This article is intended to provide a brief introduction to the concept of 
telecommunications, so that even if you don't currently know a bit from a baud,
you can get some idea of what telecommunications is and what you can do with it.

   Basically, telecommunications is the transmission of data between computers 
by telephone.  You may be used to thinking of the phone as a way to send your 
voice over long distances, but your computer can use the same lines to send 
text, data, and programs to other computers.  To do this, there is some 
equipment and software you need, and some terminology you must understand. 

   A ^1modem^0 (short for ^1Mod^0ulator-^1Dem^0odulator) is the major device you need to
begin telecommunicating.  It changes the binary data used by your PC into a 
series of tones which can be sent over the phone.

   There are several kinds of modems.  The oldest type is the "acoustic 
coupler", which has two indentations into which you place your telephone 
receiver once you have dialed the proper number; it then "talks" on the phone 
by sending and receiving tones through your receiver.  These modems are fairly 
cumbersome, and are no longer in common use except on portable terminals 
intended for use by travellers. 

   Newer modems are of the "direct connect" sort, which can be plugged directly 
into a modular phone jack.  If you have the older type of phone jack, with four 
holes, you need an adapter to connect a modem to it.  Direct connect modems can 
dial calls directly (using either touch-tone or rotary-dial "pulse") and most 
can also answer calls if you instruct it to.  You don't need a separate phone 
to use a direct connect modem.  Since you don't have a receiver to listen into, 
many modems have a built-in speaker to let you hear it while it dials, so you 
know if you got a busy signal, no answer, or a human being answering and 
wondering why she is getting nothing but a high-pitched screech in return.

   Modems can be "internal" or "external."  An internal modem plugs directly 
into a slot inside your computer.  An external modem is outside your computer, 
and must be attached to a serial port.  Some computer models have built-in 
serial ports, while others require a serial card to be plugged into one of the 
slots.  There is a standard type of port, called ^1RS-232^0, which most external
modems require. 

   Other features differ between modems.  The most important is the speed at 
which they transmit data, measured in bits per second (bps).  The term ^1baud^0 is
frequently used interchangeably with ^1bps^0 in referring to modem speed, but this
is not quite technically accurate.  Actually, a "baud" means one change in the 
signal level of the modem.  Early modems could only transmit one bit (a binary 
digit, either 1 or 0) per change in signal, so the rate in baud and bps was 
identical.  However, many newer modems use multiple frequency channels and 
signal levels to transmit more than one bit per baud, so the baud rate is no 
longer equivalent to the bps rate.  Most users fail to make this distinction, 
though, so in common usage the term "baud" has come to mean "bits per second."  
I often use it in that manner myself, although I know better. 

   Throughout the history of modems, there has been a steady increase in speed.
Early modems transmitted at 110 bps or slower.  Later on, the 300 bps modem 
came along, and was for a while the dominant speed for personal computers. It 
is still used on inexpensive home systems, but most serious telecommunicators 
have upgraded to 1200 bps.  2400 bps modems are also widely available, but are 
still not quite as common as the slower speeds.  Even faster modems, such as 
9600 bps, are starting to show up, but are relatively expensive.  No consistent 
set of standards has yet been adopted; not all 9600 bps modems can "talk" to 
one another.  Speeds up to 2400 are pretty standardized, at least in the U.S.; 
you can probably communicate with any other modem of your speed.

   Also, modems are generally "downward-compatible" with lower speeds; if you 
are calling a system with a slower modem, you can use your modem as if it were 
also slower.  The data will be transmitted at the slower speed of the two 
modems involved.  You probably need to know in advance what speed the modem at 
the other end is, so you can set your modem to talk at that speed; otherwise, 
the data will come out as nothing but garbage.  Some modems, however, are 
capable of sensing the speed of the other modem and adjusting accordingly.

   Once a modem is connected, the next thing you need is a terminal program.  
^1ProComm^0, included in this issue, will do the trick.  It allows you to place 
calls to other computers, and perform file transfers.  Read the file about 
^1ProComm^0 for more details about what it does. 

   Okay, you're all set up now; what do you do with it?  Glad you asked.  There 
are a number of services you can call.  These include commercial services like 
CompuServe, The Source, Mnematics, People/Link, Dow Jones News/Retrieval, 
Delphi, and many others.  We have arranged for special offers for some such 
services, as well as for a modem; look inside the package that ~3|9BIG BLUE DISK^0
came in for the coupons, and check out the "Special Offers" article.  We suggest
you take advantage of these offers and sign up for some of the services, and 
look around to find something of interest to you. 

   Features on these services include bulletin boards to post your notices, 
forums to engage in debates and discussions on various topics, online games, 
air travel reservation services, news databases, downloadable programs, and lots
more.  One very popular feature is electronic mail (E-Mail); some services (MCI 
Mail, AT&T Mail, EasyLink, etc.) are devoted entirely to this.  See the next 
article for more details on E-Mail. 

   If your budget doesn't permit use of commercial services, which usually 
charge by the hour, then you might want to check out free public bulletin board 
systems (BBS's).  There are thousands of them all over; if there is one in your 
town, you won't even have to pay long-distance phone bills to use it.  Since a 
BBS is usually run as a hobby, there is generally no direct charge.  Your local 
computer users' group probably knows some BBS numbers.  You can call our own 
BBS at (318) 636-4402; we have several lists of other BBS's online for you to 
list or download. 

    Happy telecommunicating!
