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Text File | 1988-09-25 | 17KB | 398 lines

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.