A Telecommunications Primer
===========================
Barton M. Bresnik Coelho Middle School
bresnik@meol.mass.edu June 29, 1995
Overview
Telecommunications is a catch-all word for a variety of electronic media:
facsimile or "fax"; transmission of words, sound, pictures, or other data
between terminals or computers; voice mail; and newer services, such as "video
telepresence" conference. Here are some connections you may make with a
computer and modem:
Someone to Talk to...
Person-to-person calls allow communication with the hearing impaired and
provide a permanent, unambiguous record of conversation. You may also use a
person-to-person contact to play games such as chess, cards or aerial combat
simulation or to transfer data, such as tax files to your accountant, or
vacation photos from your children.
Local bulletin board services (BBS's) are a means to post and retrieve
messages, to seek computer assistance or to meet people sharing your
interests. For example, the Zoning Board in North Attleboro provides freeware,
information on various types of computers and games, and a public forum. Local
BBS's are an ideal place to practice using your system, as the "netiquette" is
usually informal and cost, zero. Just call the BBS and use it!
Commercially operated or government maintained BBS's are often free (other
than telephone tolls) and are designed to provide public or consumer
information. For example, Canon provides a library of files to support theirprinters and NASA offers the SpaceLink to disseminate aerospace news such as
enrollment information on Space Camp.
Online services, such as America Online, CompuServe, Delphi, GEnie and
Prodigy provide numerous services for a monthly fee. On GEnie, I regularly use
software libraries to get programs for Atari, Macintosh and PC computers; send
e-mail messages both to GEnie and to other users of other services; employ
Grolier's Online Encyclopedia for research; use EAASY Sabre to check air
fares; read movie reviews, Reuters' news reports... well, there are hundreds
of services available for the basic fee. These online services also provide
access to the Internet, q.v. Other facilities, such as performing key-word
searches of periodicals or making a stock market transaction, may have a
surcharge added (you're usually warned beforehand of any extra cost). Some
online services charge extra for most benefits: check the rate structure
before subscribing!
Internet service providers are primarily devoted to getting you to the
access ramp of the "Information Superhighway", but don't provide on-the-road
service. Some use a dial-up account, over regular 'phone lines, to their
computers, which then connect to the 'net and shuttle information back and
forth; you access their computers with a terminal emulation program (usually a
DEC VT100 terminal) on your machine, while they operate Pine, Lynx or other
software to talk on the 'net for you. Massachusetts Education On Line, .meol,
uses this sort of "comand-line access"; I find it quite convenient. If you
want to see the graphics and hear the sound effects immediately, though, you
need a high speed connection called Serial Line Internet Protocol (SLIP) or
Point to Point Protocol (PPP) and a program such as Mosaic. This may be
somewhat more expensive, as you need a faster modem, a higher level of the
provider's service, and, often, a faster computer and a high speed "telephone"
line. Certainly, adequate service may be provided by a dial-up, command-line
account from an Internet service provider (or the more general online
services, such as America Online or GEnie, which also provide menu-driven or
command-line accounts); you may upgrade to a SLIP or PPP account if the
situation actually warrants it.
Paying the Tolls...
There's no need to spend much for a basic system: almost any computer may
use telecommunications software and a modem. If you're purchasing a new
system, consider:
Used IBM PC or clone, with at least a '486 microprocessor,
4 megabytes memory for DOS applications (or more RAM for
Windows applications) and VGA monitor: less than $600
Used Mac's are also a fine choice.
Modem: new or used 14,400 bits per second (bps): less than $100
or new 28,800 bps, v.34 high-speed (the best) less than $200
Telecommunications software: (freeware) free
Telephone line: use your normal telephone line no extra cost
Use virtually any computer you might have, but don't scrimp on the modem:
higher speed makes use more enjoyable and also will save money in the long
run, as most services still charge for the time connected, as does Ma Bell!
Fees vary: a local telephone call to a BBS should be free; connection to a
local node of an on-line service also is not a toll call. Some services may
need either a long-distance call or a call through a low-rate network, such as
SprintNet, for a few dollars per hour. In addition, online services and
Internet service providers have a monthly rate and/or an additional hourly
rate. Some services may have surcharges for products which, from others
providers, are free. To put this in perspective, my own monthly bill averages
$14, but a friend, enamored of online games and chat, ran up a $300 bill over
one holiday!
Note that you do not need a new or separate telephone service, though you
do tie up the 'phone while the modem is actually running. By the way, disable
call-waiting, if you have that service, while telecommunicating, by dialing
the code provided by the 'phone company, or your telecommunications may be
interrupted.
Making Connections...
Plugging the modem into the computer and an existing 'phone line may take
as long as fifteen minutes, if you open the computer to install an internal
(card) modem. Setting up software (a telecommunications, or comms, program) to
automatically dial a number and log on with your password may take an hour.
Some online services, such as America Online and Prodigy, require you to use
their proprietary programs, but these programs often install themselves on
your system. Setup varies and goes beyond the scope of this article, but a
setting of 8-N-1, local echo off is common [don't worry about these
parameters; once set, you rarely alter 'em].
There are commercial comms programs, but freeware or shareware offer a
chance to use your system for little investment. These programs may be
downloaded from many sources, or, to get your first program, I can provide
freeware.
Glossary
application software or program
ASCII numerical code for transmitting letters and other
characters using seven "bits" [eight bits in extended-ASCII
format] per character: A=65, B=66...
baud rate of data transmission (2400 is acceptable, but 28,800
is the best, today)
BBS bulletin board system: post messages, send e-mail, download
or upload files, play games...
bit one binary digit: 1 or 0, on or off; one bit of information
bps see baud
byte group of eight bits; often used to represent one
extended-ASCII character
capture buffer record of your telecommunications session kept in memory;
very useful!
COM Port RS-232 port and the area of the Operating System to which
it reports. Due to IBM PC idiosyncrasies, the modem, which
may use COM port 3, could conflict with the mouse or other
serial devices!
communications
software an executable file that enables the computer to "talk" to
modem and other computers. Also called "terminal program".
modem and other computers. Also called "terminal program".
cps characters per second, about one tenth the baud rate or bps
d/l see download
download receive a file, such as text, a program or picture, from
another computer
e-mail electronic mail; a message to another person or company
facsimile "fax", sending a "photograph" of a page, with graphics as
well as text; some modems can also send and receive fax, if
you have the right software
file transfer u/l or d/l a file; ftp or http are a means to transfer
files on the Internet
freeware software that is cost-free
ftp file transfer protocol; a pattern the software follows in
transferring files
hypertext text which contains "links" or cross-references to other
articles: just point at a highlighted word or phrase, and
the cross-reference is found!
http hypertext transfer protocol; accesses information by "point
and click"
Internet communications pathway started by the Department of Defense
to assure dispersed, redundant information storage,
processing and transfer in the event of national disaster.
This was given to education and industry, and has recently
This was given to education and industry, and has recently
been opened to commercial traffic.
Kermit protocol for file transfer; not as easy or quick as zmodem
link within text, a pointer to other resources on the 'net
Lycos a browser to locate resources on the Internet
Lynx hypertext-based Unix program that allows PC's to access the
Internet; it actually is run by your service provider.
modem device that connects the computer to the 'phone line
parallel port connection on the computer for data transfer; most often to
a printer
online service for a fee, provides software libraries, e-mail, Internet
access and many other services
public domain software or files that don't claim copyright protection
serial port connection on the computer for data transfer, one bit at a
time; used by modem;may be implemented over ordinary
telephone wire (twisted pair)
service provider the company, school or other entity connected to the
Internet over its high-speed data connection, which, in
turn, connects to your house via your regular telephone wires.
shareware program which you may sample freely, but are expected to
buy if you use it often!
software programs or applications which "run" on a computer sysop system operator person in charge of the computer system
telnet using your computer as if it were actually a terminal
connected to a host system
terminal emulator program that imitates a "dumb terminal". All that vaunted
power in your computer is bypassed so that it simply
displays and records what's sent by the modem. Most
commonly, an emulation of a Digital Equipment Corporation
model VT100, though VT52 and VT102 are also used.
u/l see upload
upload send a file (text, MID, GIF etc.) to another computer
URL Universal Resource Locator, i.e., ftp, http, telnet, etc.
Usenet bulletin board cum newsletter on the Internet
Web Crawler a browser to locate items on the Internet World Wide Web
WWW Internet sites linked by hypertext files and pointers
xmodem moderately simple file transfer protocol
ymodem efficient file transfer for batches of files
zmodem easiest to use and very efficient file transfer protocol;
it will automatically put the files on your disk drive
Some Places to Call...
America Online (800) 827-6364 x3507 (voice) online service
CompuServe (800) 524-3388 (voice) online service
Delphi (800) 365-4636 (modem), (800) 695 4005 (voice) online service
GEnie (508) 222-7550 (modem), (800) 638-9636 (voice) online service
Internet Connection (508) 261-0383 (voice) Internet access
IDS (401) 884-9002 (modem), (401) 884-7856 (voice) Internet access
SpaceLink (205) 895-0028 (modem) NASA (U.S. government) free BBS
Zoning Board (508) 699-0599 (modem) free BBS
b.bresnik@genie.com
Last Modified 2/21/96