BBS in a Box 5/BBS in a Box -Volume V (BBS in a Box) (April 1992).iso/Files/Tele/M/MODEM TERMS

Text File | 1988-09-25 | 16.8 KB | 398 lines | [TEXT/MSWD]

                        Hayes AT Command Summary


A/     repeat last command sent to modem

ATDT   ATtention, Dial Touch tone number xxx-xxxx ( up to 20 digits)

ATPT   ATtention, Dial Pulse number xxx-xxxx ( up to 20 digits )

     the codes below are things that can be added to ATPT or ATDT
         ,       pause before continuing to dial
         ;       return to Command mode after dialing
         R       make call but be in ANSWER mode (goes at end of number)
         !       make a HOOKFLASH ( like hanging up the phone
                                     then picking it back up rapidly )
         W       wait for second dial tone
         @       wait for silence

ATA      Attention, go into ANSWER mode
ATH0     Hang up ( goes On-Hook )
ATH1     connect to telephone line ( goes OFF-Hook )
ATO0     go OFF-Hook and wait for carrier tone
ATL0     low modem speaker volume
ATL2     medium modem speaker volume
ATL3     High modem speaker volume
AT&V     view stored and active settings
ATV1     display comments made by modem to you in words
ATV0     display comments made by modem to you as numbers
ATE0     commands typed by you are not echoed back ( you won't see
        the commands on the screen)
ATE1     commands typed by you are echoed back ( you see them on
        screen )

                            Modem Dictionary
                                 or
                           Heaps of Shinola


Acoustic Modem
A modem that requires you to dial the call manually and the put
the telephone handset ( the earpiece and mouthpiece )
in the modem. The modem has two rubber cups to hold the
handset, with a speaker in one cup and a microphone in the
other. Only older phones, with a seperate, round-ended
handset can be used. This is an older type of modem, from
the days when all modems directly connected to the tele-
phone lines had to be leased from Bell Telephone.

Answer
This refers to the type of modem. An Answer modem can only be used
if another modem calls in - it cannot be used to make
calls to other systems. This is because, in order for modems
to converse, one must start. An Answer modem will answer the
phone call and immediately send out a unique 'answer' tone.
When the Originate-type modem on the other end hears it, it
will send back a different tone and the conversation can begin.
It is not uncommon to have modems that are both Answer and
Originate types.

ASCII
A code used for text that makes it understandable to almost
any computer system when downloaded. A text-only file is
an ASCII file. Pure ASCII code is limited to anything you
can make by pressing a key on the keyboard ( except function
keys ) whether they are visible on the screen or not.

Asynchronous
One way of transmitting information. This method means'send the
data one at a time whenever you are ready'. If you listen to the
modem while data is being transferred, you will hear a constant
warble. The computer sending puts a Start Bit code at the beginning
of each character transmitted and ( at least ) 1 Stop bit at the end
so the recieving computer can pick the data out of the continuous
signal. The other kind of  transmittion is Synchronous; data is
allowed to be transferred at specific times ( believe it or not, this
is a faster type )

AT Command
A set of modem commands developed by Hayes, Inc. for their modems
which have now become what is know as 'Hayes compatible'.
The letters AT ( attention ) precede all commands to the
modem. These commands are either typed in while in the
telecommunications program, or typed by the program itself.
An example is ATM0 shuts the speaker off.

CONNECT
With a Hayes-compatible modem, when this message shows up
on your screen, the modem is telling you it has dialled the
phone number ( in Originate mode ), gotten an answer,
recieved a carrier, and responded. You can now start
communications with the other computer.

Auto Answer
The modem will automatically answer the phone and send out a tone.

Auto Dial
The modem is capable of dialing numbers ( so you don't have to ). You
can either type the number yourself, or if your
telecommunications program allows, have it send the number
to the modem.

Baud
Bits per second. How many characters a modem can transmit or
recieve is determined by dividing the baud by 10.

BELL 103
The standards for a 300 baud modem to follow to be acceptable
to the phone lines. First started by Bell Telephone in the days
when all modems were leased from them. Data is transmitted
by frequency modulation  ( like a FM radio signal ).

BELL 212A
The standards for a 1200 baud modem to follow to be acceptable
to the phone lines. First started by Bell Telephone in the days
when all modems were leased from them. Data is transmitted
by phase modulation ( PM ).

Bit
The smallest piece of information in a computer. Think of it
like an atom - by combining it with other atoms all sorts
of larger things are possible. A bit has two possiblilities:
On or off ( just like a light switch ). This is called binary.
When communicating a certain number of bits are necessary for each
letter, number or punctuation sent.

BPS
Bits per second, same thing as BAUD, but slightly more explicit.

BUSY
When this shows up on your screen, and you have a Hayes-compatible
modem, it means the number that was dialed is busy.

Capture Buffer
Setting this to On means that everything that shows up on
the screen will be 'captured' or retained and stored in a file
in text form. After you finish on the modem, you can call up the
program with your word processor and review or edit it and print
it out. Set the capture buffer to Off if you don't want to record
what you do.

Carrier
The tone you hear from your modem when it isn't transmitting
information, but still talking to another modem.

Character
Any symbol that is text that can be displayed on the screen. What
you are reading now are characters. But, pressing "Butterfly" - C
will not show on the screen.

Control-C
This means to press the CONTROL key,hold it down,press the C key,
then release both. This tells the computer to stop whatever it is
doing. On the Macintosh, the CONTROL key is the "butterfly" key.

CRC
Cyclical Redundancy Check. A better form of error checking of
transmitting data than the Parity method.

data
A data is 1 character, like 'a' or '&' or a Line Feed. It is
made up of 10 smaller pieces, called bits. data also refers to all the
individual data sent out.

DB-25
The 25-pin connector that the cable is connected to. This
carries the data from the computer to the modem and back.

Direct Connect Modem
One that meets certain minimum standards and is therefore
connected directly to the phone lines. An actual telephone
is not necessary to use this type of modem.This is the most
common type of modem today

Download
Receiving information or programs into your computer through a
modem from another computer

Full Duplex
Setting this on your software says to send the data
( from a file or the keyboard ) directly to the modem and
do not send it to your computer screen. This feature is
used if the computer on the other end is set to 'echo'
what you type back to you over the modem - since you
whether you do full-duplex or not.

Half Duplex
Setting your computer for this will tell your computer to not
only send the data ( from a file or the keyboard ) to the
modem but to send it to the screen on your computer too.
This is used ONLY if the computer on the other end will not
be sending what you type back to you ( echo-ing ). If you choose
this while talking to another computer that has echo-ing, every
time you transmit a character, it will show up twice on your
screen ( once from your computer and once echo-ed from the
other computer ).

Handshaking
A means of controlling the modem from the computer. Software
handshaking is called X-ON/X-OFF. Hardware handshaking
involvesusing extra wires in the cable; the modem expects to see
certain signals on the wires in order to operate. The two most
common harware standards are DTE and DCE ( refering to the name
of the pins on the cable that carry the handshake signal ).
This method is the reason cables are so expensive - the connectors
on modems and computer ports are not standardized.

Hayes
The standard by which 300 and 1200 baud modems were compared.
The company Hayes was the most popular microcomputer modem
maker at one time, with modem features that can be changed
via computer by the user. These feature codes were written into
several popular telecommunication programs - so if you wanted
to use the program, you had to have a Hayes computer. Other
Manufacturers started to make modems that emulate the Hayes:
these are called Hayes-compatible modems. Care must be taken
in determining how much Hayes-compatible a modem is; some
modems use only a few of the Hayes codes.

Line
Typically, a line of text has 80 characters.

MNP
Microcom Networking Protocol. Six levels of data compression
and error correction techniques that allow a modem to comm-
unicate at a faster than normal rate. Levels (classes ) 1 - 6

Nonvolatile memory
RAM inside the modem that holds information you have programmed
into the modem through your computer. This special RAM does
not erase itself when the power is turned off. Information that
you may be able to program in are things like AT commands,
phone numbers, or passwords.

Null Modem Cable
A cable that connects two computers together through the modem
connectors ( on the computers)  without using modems.  The cable
connects directly to the computers, allowing the
computers to talk much faster than if the modems were used.
This kind of cable is only useful if the computers are
nearby; stringing a cable across town to another computer
would be very expensive. NOTE: this cable CANNOT be used
to hook a computer to a modem - the signal wires are not
on the proper pins that the modem needs.

Off-Hook
This term goes back to the days when phones were all mounted
on the wall and the listening and talking part was hung on a
the telephone, ready to communicate.

OK
On a system with a Hayes-compatible modem, this message
showing up on the screen means you have just sent a command
directly TO your modem ( not through the modem to somewhere
else ) and that the modem understands what you said.

Originate
This refers to the type of modem. An originate modem can only
be used when calling another modem - it cannot itself be called
by some other modem. This is because, in order for modems to
converse, one must start. The modem you call up sends out a
tone once it answers. When the originate modem 'hears' this tone
it responds ( with a different tone ). It is not uncommon to
have a modem that can both Orig

Page
Typically, a page has 60 lines, of 80 characters each. Thus,
the total characters in a page is 60x80 or 480 characters

Parity  - Parity is a very simple, but not foolproof, way of detecting
if what was just recieved over the modem is what was transmitted.
Each piece of data transmitted is actually sent an a number.
This number, called ASCII, is like a code for the keyboard:
when you started school you were taught that 'A' is the first
letter in the alphabet, so the code for 'A' was 1. Well, parity looks at
the code before its sent, then sends a message  WITH THE CODE to
the recieving computer which checks the parity
against the code to see if the code has changed. If it has, the
recieving computer asks that the character be sent again.
There are three types of parity: (E)ven, (O)dd, or (N)one.
Although far from the best type of error detection, it is
the most widely used ( its cheapest ) and almost every computer
uses it - some will use other types in addition.

Port
No, this is not a mixed wine. A computer port is a connection
on the computer to 'the outside world'. The connector for a
mouse, a video screen, a printer, or a modem are all ports.

RS232C
The most common type of serial transmission. RS232 is a set of data
transfer procedures, and more importantly, a set
of standards for voltages and pin useage on a serial
connector ( like on a modem ). It specified a connector have
25 pins and certain pins have certain uses. Unfortunately,
the guidelines were somewhat vague and the idea of a
standardized connection failed. The only thing RS232 means
now is that the signals won't blow up if you hook the wrong
cable up, and that the signal levels are within specific
values.

S Registers
RAM locations inside the modem that hold information about
certain functions that the modem performs ( note that this
is a creation of Hayes Inc. and is part of what is termed
'Hayes compatible ). An example is S9  ( the ninth S
 register ) which holds the information on how long to
wait for the modem tone ( carrier ) to show up before
hanging up.

Serial
A form of moving data by one wire. Since a computer deals
with data that is at least 7 bits long, and modems can
only handle 1 bit at a time, the serial section of the
computer must convert from 7 bits ( or more ) all at once
to a way of sending all the bits out, but one at a time.

Smart Modem
Any modem that can automatically perform functions: any
Hayes-compatible. Functions are dialing phone numbers,
answering the phone,...etc.

Start Bit
This is a bit put at the beginning of every character to be
sent to indicate the beginning of a new character to the
recieving computer modem. There is always 1 start bit.

Stop Bit
There is at least 1 stop bit at the end of each character
to be transmitted ( sometimes 2 ). The stop bit tells the
recieving computer " This is the end of the character -
start looking for another character and process this one."

Talk
If your modem has a TALK/DATA switch, then you have a way of
manually attaching the modem in originate-mode. When the
button is in the TALK position the modem is electrically
connected from the phone line, and any telephone connected
to it will work. When the switch is in the data position, the
modem is connected and the telephone is disconnected ( in that
order - otherwise the phone company would think you hung up ).
So, TALK means just that - when YOU want to use the phone, and not
use the modem.

UART
(U)niversal (A)sychronous (R)eciever/(T)ransmitter
This is a chip inside the computer that converts the character
codes from the type it uses to a serial format. The modem can
only handle one small piece of the character code ( a bit )
at a time - it only has one line to send the data throught -
and so the UART properly feeds the pieces to the modem.
( Think of it like a gun and its magazine. You can load
a 7-shot magazine in a gun, but it shoots one bullet at
a time. And, the recieving target gets the bullets one
by on and eventually has all the bullets at the same
time).   The UART also attaches the stop bits and start bits, and
calculates the parity and adds it on. That is the Transmitter
part. The same chip also recieves data from the modem, strips
off the stop,start, and parity, checks the parity, and
converts the character back to a form the computer can use.

Upload
Sending a file or program from your computer to another
through the modem.

V.22bis
The communications standards set forth by an international
committee ( CCITT in Geneva ) for 2400 baud modems.

V.29   V.32
Standards for 4800 and 9600 baud modems.

X-MODEM
A communications protocol ( not related to the modem at all,
but to the method in which the data is transferred from one
computer to another ). To use X-MODEM to download or upload
data, both computers must be set for X-MODEM. Y-MODEM   A more
sophisticated communications protocol than the  X-MODEM. A method
of transferring data from one computer to another ( has nothing to
do with controlling or standards for
the modem ). Almost all telecommunications programs support
Y-Modem as well as X-Modem data coding.

X-ON
This means "Transmission ( of data ) On "; to go ahead and
send data. If your computer is ready to get more data during
a download it sends a X-ON signal to the transmitting computer.
You can send X-ON yourself by pressing "Butterfly" and "Q" at the
same time.

X-OFF
This means "Transmission ( of data ) Off "; to stop sending data for
now - just wait. If the memory of your computer gets full,
it sends this to the transmitting computer to stop sending until
it dumps the memory into the disk. Then it sends an X-On to
continue transmitting. You can send X-OFF yourself by pressing
"butterfly" and "S" at the same time.