When you consider buying a modem with higher speed, remember that going from 1200 bps to 2400 is a 50 percent increase, while going from 1200 to 9600 bps gives 800 percent! On the other hand, if you currently have 9600 bits/s, going to 14.400 will only give you 50 percent.
MNP error correction and compression —————————————————— The Microcom Networking Protocol (MNP) is a U.S. industry standard for modem-to-modem communication with automatic error correction and compression. Automatic error correction is useful when there is noise on the telephone line. MNP splits the stream of data up into blocks before transmission. They are checked by the other modem upon receipt. If the contents are correct, an acknowledge message is sent back to the sending modem. If there has been an error in the transmission, the sending modem is asked to retransmit. When using compression, files are being preprocessed before transmission to decrease their size. The result is that the modem has to send fewer bytes, and the effect is higher speed. MNP Level 3 and up send data between two modems synchronously rather than asynchronously. Since sending a start and stop bit with each transferred byte is no longer required, the effect is higher speed. MNP-4 or higher have automatic adjustment of block length when there is noise on the line. If the line is good, longer blocks are sent. The block size is decreased if the line is bad causing many retransmissions. MNP-5 has data compression. This gives a further increase in transfer speed by from 10 to 80 percent depending on the type of data sent. MNP-7 is capable of a three-to-one compression ratio. Both users must have their modems set for MNP to use it.
The speed of the computer's COMM port ——————————————————- Installing a super fast modem does not guarantee an increase in the effective transfer speed. The serial port of your computer may be a limiting factor. Owners of older MS-DOS computers often have UARTs (serial port processors) in the Intel 8250 or National 16450 series. With these in the computer, it is difficult to achieve speeds above 9600 bps without losing data. Take this into account when investing in a modem.
MNP and efficiency ————————— I call my bulletin board daily. My personal computer is set to communicate with a V.32 modem at 19,000 bps. The modem sends data to the telephone line at 9600 bps, which is this modem's maximum line speed. Data is received by the remote computer's V.32 modem at 9600 bps, and forwarded to bulletin board at 19200 bps. Why these differences in speed? MNP level 5 compresses data in the modem before transfer, and gives error-free transfer to and from the bulletin board at higher speed than by using 9600 bps all the way through. The compression effectiveness differs by the type of data. When sending text, the effective transfer speed may double. Speed will increase further if the text contains long sequences of similar characters. Text is typically compressed by up to 63 percent. This means that a 2400 bps modem using MNP-5 may obtain an effective speed of around the double when transferring such data.
File transfers using MNP ———————————— Files are often compressed and stored in libraries before transfer. Online services do this because compressed files take less space on their hard disks. Also, it is easier for users to keep track of files sent in a library file. You rarely get speed advantages when transferring precompressed files using MNP or V.42bis. With some modems, you must turn MNP and V.42bis compression off before retrieval of compressed files.
Dumb or intelligent modem? ————————————— Some modems are operated with switches or buttons on a panel. They do not react to commands from your computer. We call them dumb. You must dial numbers manually, and press a key on the modem, when you hear the tone from a remote modem. Only when the modem is connected to the remote modem, can you ask your communications program to take over. We call those modems 'intelligent' that can react to commands from your computer. Most of them react to commands according to the Hayes standard. Buy intelligent, Hayes-compatible modems - even when other standards may seem better. Most of today's communication programs are designed to be used by such modems.
Note: Buy modems that use the Hayes extended command set.
When a popular communications program, like Procomm and Crosstalk, tells the modem to "dial a number" or "go on hook," then the Hayes- compatible modem will do just that. When you press ALT-H in Procomm, the modem will disconnect from the remote modem. If you press ALT-D followed by the number "2," Procomm will locate the number to an online service in your telephone directory, and dial that number. When the connection with the remote modem has been established, your modem will report back to you with a message like CONNECT 2400. This tells that a connection has been set up at 2400 bps. If I select "k" from a menu provided by my communications program's command scripts, then my system will retrieve today's business news from Tokyo and put them up on my screen. In the process, my system tells the modem to do several things, including "call a number," "speed 2400 bps," "redial if busy," "go on-hook when done." The only thing that I have to do, is press "k". The communications program and the modem will do the rest. Automatic communication is impossible without an intelligent modem.
The Hayes standard ————————— The U.S. company Hayes Microcomputer Products, Inc. pioneered command-driven modems. Their Smartmodem became a success, and "Hayes compatibility" a standard for intelligent modems. Today, it is as unimportant to buy a Hayes modem to get access to Hayes commands, as to buy an IBM PC to run PC software. Automatic dialing (autodial) was one of Smartmodem's important features. The modem could call a number and prepare for data communication, once a connection had been set up. If the line was busy, it could wait a while and then redial. The operator could work with other things while waiting for the equipment to be ready for communication. The modem had automatic answer (autoanswer), i.e., when someone called in, the modem could take the phone off hook and set up a connection with a remote modem. The modem enabled a connected PC to act as an electronic answering machine. Hayes-compatible modems can report call progress to the local screen using short numeric codes or words like CONNECT, CONNECT 1200, CONNECT 2400, NO CARRIER, NO DIALTONE, BUSY, NO ANSWER, RING etc. There can be small differences between such modems. The message DIALTONE on one modem may be DIAL TONE on another. Most of the main progress messages, however, are the same across brands. The old Smartmodem had switches used to configure the modem. Most modern Hayes-compatible modems come without switches and have more commands than their ancestor. Today's Hayes-compatible modems have a core of common commands, the "real" Hayes-commands, and several unstandardized additional commands. Here is an example:
A standard on the move ——————————— On the Quattro SB2422 modem, 2400 bps speed without automatic speed detection is set by the command "AT&I1." The equivalent command on Semafor's UniMod 4161 is "AT+C0". Automatic detection of speed is a feature that lets the modem discover the speed of the remote modem to set its own speed at the same level. (Other modems may use different commands to set this.) When I want Procomm to call a bulletin board, it first sends a sequence of Hayes commands to the Semafor modem. The purpose is to "configure" the modem before calling. It sends the following:
AT S0=0 +C0 S7=40 S9=4 &D2
The cryptic codes have the following meaning:
AT "Attention modem. Commands following.." S0=0 No automatic answer +C0 No automatic speed detection (fixed speed) S7=40 Wait 40 seconds for an answer tone from the remote modem. S9=4 Wait 4/10 seconds for detection of carrier &D2 Go on-hook if the DTR signal is being changed.
If this command is sent to the Quattro modem, it will reply with "ERROR". The code "+C0" must be replaced with an "&I1". The rest of the commands are the same. (Note: when a modem responds with "ERROR," it has usually rejected all commands sent to it!) This setup is held in the modem's memory when Procomm sends its dialing command: ATDT4737031378. AT stands for ATtention, as above. DT stands for Dial Tone. Here, it is used to dial the number 4737031378 using tone signaling (rather than pulse dialing).
The modem cable ———————- If you have an external modem, you must connect your computer to the modem with a cable. Some modems are sold without a cable. This cable may be called a serial cable, a modem cable, a RS232C cable, or something else. Make sure that you buy the correct cable for your system. Make sure that the connectors at each end of the cable are correct. If a male connector (with pins) is required in one end and a female (with holes) in the other, do not buy a cable with two male connectors. Some connectors have 9 pins/holes, while others have 25 or 8- pin round plugs (Apple computers). Use a shielded cable to ensure minimal interference with radio and television reception. At this point, some discover that there is no place on the PC to attach the cable. Look for a serial port at the rear of your machine, labeled MODEM, COMMUNICATIONS, SERIAL, or with a phone symbol. If you find no suitable connector, you may have to install an asynchronous communication port in the box.
Connecting your equipment to earth ————————————————— Secure your computer and modem against thunderstorms and other electrical problems. Securing the electric outlet in the wall is not enough. Problems can also enter through the telephone line. Thunderstorms have sent electrical pulses through the telephone line destroying four modems, three PC-fax cards, one mother board, and at least one asynchronous communication port. To prevent this from happening to you, disconnect electrical and telephone cables from your equipment during thunderstorms.
The communications program ————————————— A powerful communications program is half the job. In my case it's the whole job. Most of my work is done automatically. The communications program will help you with the mechanical transportation of data in both directions. It lets you store incoming information for later use and reduces the risks of errors. Here are some items to consider when shopping communications program: * Seriously consider buying automatic programs ('robots') for access to individual online services, even if that means having to use several programs for different applications. (Read chapter 16 for more details.) * Menus and help texts are important for novices, and in environments with "less motivated personnel." Advanced users may find it boring. * Ability to transfer data without errors. The program should have transfer protocols like XMODEM, Kermit, XMODEM/CRC, YMODEM and ZMODEM. The XMODEM protocol is the most commonly used. You need these protocols if you want to transfer compiled computer programs (e.g., .COM and .EXE files). They are also used when transferring compressed files, graphics and music files. * Does it let you tailor it to your taste/needs? Some programs let you attach batches of commands to function keys and keypress combinations. For example, by having your computer call your favorite online service by pressing the F1 key. * Does it let you "scroll back" information having disappeared out of your screen? This may be useful when you want to respond while online to an electronic mail message. The sender's address and name, which you need to respond, have scrolled off the screen. If you cannot review the "lost" information, you may have to disconnect and call back later to send your mail.
Connecting to the online service ———————————————— The first couple of times, most people think that it is very difficult. Soon it becomes a simple routine. On some computers, you just press a key, and that's it. On others, you have to call and press, and watch, while things are happening. Cheap is often a synonym for more work. If you have a dumb modem connected to your personal computer, these are the typical steps that you must take:
(1) Start your communications program and set it up, e.g., with2400 bps, 8 bits word length, 1 stop bit, no parity. (Thisis the most common setup.) Then set the program to "online."(2) Call the number (e.g., +47 370 31378)(3) When you hear the tone from the remote modem in the phone,press DATA to get the modems to connect to each other(i.e., to start to "handshake").(4) A front panel indicator may tell you when the connectionhas been set up. You can start transferring data.
With an MS-DOS computer, an automatic modem and a powerful program preset for the job, the steps may be as follows:
(1) Start the program and display the telephone directory.Select a service from the list by pressing a number.(2) The modem will call automatically to the service. WhenCONNECT has been established, your user identification andpassword are sent at the prompts for such information. Whenthis is done, you are free to take control.
With an MS-DOS computer, TAPCIS, and an intelligent modem, you start by selecting forums and services to access on CompuServe. Enter 'o' to upload and download programs, or 'n' to have it fetch new message headers and messages. TAPCIS will dial the number, do the job, and tell you when it's done. Meanwhile, you can go out to look at the moon, or sing a song.
Getting started with Procomm —————————————— Procomm is cheap and probably the most commonly used communications program for MS-DOS computers. It's been like this for many years, though there are many better and cheaper alternatives. An older version of the program (version 2.4.2) is still being distributed through bulletin boards all over the world. You may give copies of this version to anyone. The requirement is that you pay a contribution of US$25 to the vendor if you like it and start to use it. Procomm is simple for novices, can automate the work for advanced users and be run on almost any MS-DOS computer. Here is some of the features: Press ALT-F10 for a pull-down window text listing features and commands. Press ALT+D to call a number, update the telephone directory, or select a script file for autologon to a service. Procomm can emulate (pretend to be) different terminal types, like IBM 3101 and DEC VT-100/VT-52. Most services covered in this book may be well served with the setting ANSI.BBS. It let you use both dumb and intelligent Hayes-compatible modems. If you have the latter, select numbers from the telephone directory for autologon. If the number is busy, Procomm can call back until you can get through. You can define macros to automate your work. You can have one keystroke send your user identification, another for your password, and a third key to send a sequence of commands. Macros make your communication faster and safer. You can write script files to automate the online work further. You can transfer text files and binary files using automatic error detection/correction protocols, like XMODEM, YMODEM, Telink and Kermit, at speeds from 300 to 19200 bps. Adding external protocols like ZMODEM is relatively simple.
Appendix 3:
Online with the world =====================
- Practical data communication- Your first trip online- Typical pitfalls and simple solutions- Receiving (downloading) letters, text and programs- Sending (uploading) letters, text and programs
Practical data communication —————————————— The first thing novices want to know is how to set up the modem and computer for communication. This may take more time than expected and often seems complex for the uninitiated. You can save yourself much sweat and frustration by asking others for help. To set up your equipment for communication is a one time job. Once done, you can almost forget what you did and why. There are so many different modems, computers and programs out there. We just cannot give practical advice on the use of all of them in one short appendix. Instead, we will use one example. Your job is to "translate" the text into a terminology that fits your tools. Once your system is set up for communication, your first job will be to find what keys to press to get the job done. How you use your communications program may vary considerably from our example. In general, however, it will be the same for most people doing manual communication. Once online, the environment is the same for all users. If you plan to use automatic communications as explained in chapter 16, this chapter may not be that important. Your program will do the job for you. Still, take a few minutes and browse through the text. It may enable you to handle unexpected problems better. Our example assumes that you have an MS-DOS computer. Not because this is the best microcomputer in the world, but because there are more of them than anything else. We assume that you have an external, intelligent Hayes-compatible modem and the communications program Procomm (version 2.4.2). In this example, your modem is tested by calling my bulletin board at +47 370 31378. Not because this is the best board in the world, but because I have full control over how it looks and feels for those using it.
Assembling the equipment ———————————— You have the modem, the cable (to connect your modem with the computer), a phone cable (to connect your modem with the phone or the wall jack), and a communications program. Check that the modem's power switch is off. Place the modem by the computer, and plug the power supply cord (or the power adapter cord) into the AC wall socket. Switch on the modem.
Do NOT use 115-volt equipment in 250-volt sockets!
Connect modem and computer using the modem cable. There may be several optional sockets on the computer. These are usually marked RS-232, COMMS, MODEM, or just nothing. The connector may be of a flat 25-pins, 9 pins, or a round 8-pins type. Use communication port number 1, 2, or whatever else is available for this purpose. If you have several options, and the socket for communication port number 1 seems free, use this. If not, try one of the others. Next, connect the modem to the telephone line. If in luck, the modem came with a phone cable that works with your setup. If so, it is simple: 1. Disconnect the phone cable from the telephone. Insert the modular plug into the right jack on the modem. This jack is often marked with the word LINE, with a drawing of a modular wall jack, or another understandable icon. 2. You may be able to connect the phone to the modem using the phone cord that came with the modem. This may allow you to use the phone for voice, when the line is not busy with communication. (You may have to make changes in this cord to make it work with the connected phone.) This concludes the technical assembly of your equipment. Next step is to install the communications program. When this is done, we will check it out.
Installing the program ——————————— Let us assume that you have received Procomm on a diskette, and that it is set up with its default configuration. PROCOMM.EXE is the program. The other files have no importance here. Enter Procomm and press ENTER. Our first task is to prepare it for communication: If you are using a monochrome display, use the command
The program will greet you by a welcome text. At the bottom of the screen, the message "CREATING SYSTEM FILES" may appear (if these have not been created yet), followed by a message from the creators of the program. Press ENTER when you have read the text. The screen will be blanked, and a text line will appear at the bottom. Now is the time to test if the technical installation has been successful.
The dial tone ——————- Lift the receiver from the phone and check if you can hear the dial tone. If you can, turn the pages to "Does the computer have contact with the modem?" If you hear nothing, there are several possible causes: * The phone is not working. This is easily checked. Disconnect it from the modem, and connect it to the wall (using the original cable!). If you get a dial tone now, then the phone is in order. * The cable between the modem and the wall jack may be broken, or wrongly configured. To check this, we must first check the connection between the modem and the computer. Once we know that the connection between the modem and the computer is in order, we can use the modem to check our phone cable. * The cable between the modem and the phone may be in disorder. For example, the modular phone connector may have a cabling that differs from what is assumed in your country. If there is no dial tone, then the cable between the modem and the telephone must be repaired, or replaced.
Does your computer have contact with the modem? ———————————————————————- When you first use Procomm, it is preset for communication at 300 bps, use of port 1 and ANSI-BBS. (The control line at the bottom of your screen should read: ALT-F10 HELP, ANSI-BBS, HDX, 300 N81, LOG CLOSED, PRT OFF, CR and CR.) * If your modem is unable to communicate at 300 bps, you must change the setup. Press ALT-P (keep the ALT key down while pressing P) to get the menu LINE SETTINGS. Choice 9 gives 2400 bps with 8 bits word length, no parity and one stop bit. This is a common setting. Select 24 "Save changes" to make the setting permanent. * If you know that your modem is not connected to the computer's port number 1, then change this from the same menu. Choice 21 gives COM2, and choice 22 gives COM3. If you don't know what communication port the modem has been connected to, you have to find out by testing. Do this by entering (i.e., sending to the modem) the characters AT. Now, the modem is supposed to respond with an OK (or with the number "0," if the modem is set to reply with numeric codes). If you get an "OK" or a "0" on your display, continue reading from "Does the modem have contact with the phone line?" If you can see "AT" on your screen while you enter it, you have contact with the modem. This is true even if it does not send any confirmation. The modem may have been instructed not to confirm. If you see the AT characters, read from "Does the modem have contact with the phone line?" If there is no contact between the modem and the computer, the screen will remain blank at all times. Your problem may be the cable, your choice of modem port, or the modem setup. First, check if the modem is switched on (the power switch), and that the plugs are firmly in the jacks. Then let's check the modem. It may have been set not to respond to your commands. Let's try to change that. Enter the following command, and press ENTER:
This should make your modem: give result codes on your screen (Q0), show the characters that you enter (E1), and use OK instead of the numerical result code 0 (V1). If you still get no OK, the reason may still be in the modem. I have seen modems get "indigestion problems" when too many commands are given to them. Try give a command to return it to its factory setting. This command is not the same on all Hayes-compatible modems. On most of them, you can use one of the following: AT&F, ATF or ATZ (on some modems ATZ is used to reset to the stored configuration). Locate the correct command to use in the modem's user manual. Then, try ATQ0E1V1 again. If you are still without success, check your choice of modem port. If there are several communication connectors at the back of your computer, test these. If this doesn't help, connect the modem cable to the most probable jack. Now, test the communication port for a response from the modem using another communications program setting. Press ALT-P, select another port (choice 20 - 23), press ESC and try "AT" again (or ATQ0E1V1). If there is still no reaction, test the computer's other communications connectors.
If you have a mouse connected to your computers, make sure that it is not using the same port as your communications program.
Problems with the communications port are often caused by other equipment. Remove all extra equipment (like a PC-fax card or a mouse), and all associated software (often represented by a line starting with "DRIVER=" in CONFIG.SYS, or a resident program driving a mouse). Remove all resident programs from memory before testing.
If you are still at the same unfortunate stage, chances are that the problem is either in the cable or the modem. If you know others who are into data communication, visit them for help. Bring your cable and your modem to have them tested in an environment where things work. It is easier to isolate a problem by testing your units in sequence on your helper's system. First, the cable. Connect it between his computer and his modem. Test the connection to his modem with your cable as the only foreign element. If the test is successful, your cable is OK. Next, the modem. If the test is successful, your modem is in order. The most probable cause of your problems is your computer's communications port.
In communications, many parts have to work together. You may have problems with more than one of them at the same time. The rule is to test step by step to eliminate possible problems.
If you get no reply from your modem, when it is connected to your friend's computer, chances are that it needs to be repaired. Call the seller for help. A last refuge is to buy an extra communications card for your computer . . .
Does your modem have contact with the phone line?————————————————————————-You have contact between your computer and modem. The modem answers"OK" as assumed. We now have to test if there is contact with thephone line. That is easy.Enter the following command and press ENTER:
When the modem answers OK, enter the dialing command:
The modem will try to call 37031378, the number to my BBS. (You may have to prefix the number with an international code, and the country code for Norway. If international calls require the prefix 009, enter ATDT009-47-37031378). Your modem will wait for CONNECT a preset number of seconds (rarely longer than 60 seconds). If your modem does not detect the dial tone (within the preset waiting time), it will give you the following error message
All other messages (except ERROR) declare that the modem did detect the dial tone. If it did, continue reading from "Configuring your program."
NO DIALTONE —————- The most probable causes of NO DIALTONE are that your phone cable is not connected, that it has been damaged, or that it is the wrong cable for the job. The latter cause is common in many countries. For example, a cable made for a telephone network in the United States, may not work in Norway. A cable made for connection to a switchboard, may not work when connected to a domestic phone line. A standard, domestic American phone cable contains four lines. Two of these (line number 1 and 4) carry sounds. The others are not being used. A standard Norwegian domestic cable is set up in the same way, but here line number 1 and 3 carry sound. Changing the configuration of such cables is often simple. Just cut the cable in two, and put the lines together correctly. This is typically required when your modem assumes that you use it in North America, while you are in a country with different cabling.
Configuring your program ———————————— The modem answers. The dial tone is being detected. Procomm is installed on your hard disk. Now, check if the program has been correctly configured. Press ALT-S to get the Setup Menu. Select 1, Modem setup, from this menu. Choice 1, Modem init string, is a general setup command. This command will be sent to the modem each time you start Procomm. You are free to make is as long and powerful as you want. Our purpose now, however, is to check if it works.
Most modems do not react if one element in your setup command is wrong. They respond with ERROR (or the numeric code), and disregard the rest.
Procomm's standard Modem init string has the following commands:
These work well with most modems, provided the speed is legal. Go back to the blank screen (using ESC). Test the init command by entering it manually. (Do not enter the "!" character. This is Procomm's code for ENTER.) If the modem reacts with ERROR, check with the modem manual to find out what is wrong. (Check if the values S7=60 and S11=55 are not too high.) If you have to change the init command, go back to the Modem init string menu choice. Enter the correct commands. Remember to add the "!" at the end. Press ESC to get to the main configuration menu and select 2, TERMINAL SETUP. Check if Terminal emulation is ANSI-BBS. Change choice 2, Duplex, to FULL. The other factory settings are NONE, CR, CR, DEST, BS, OFF, ON, 350, OFF. Return to the SETUP MENU (press ESC). Press "s" to save the setup to disk. Your setting has now been stored, and Procomm is ready to be used.
Dialing ———- Now, test your setup by calling your favorite online service. We will show how to log on to my bulletin board. You can call manually by entering ATDT followed by the phone number. The most practical method, however, is to use the built-in phone directory. Press ALT-D to get to the phone directory. Press "R" to revise the list, and enter Saltrod Horror Show somewhere on the list. I have it as number 2. Answer the questions like this:
Name: Saltrod Horror ShowNumber: 009-47-370-31378Baud: 9600Parity: NDatabits: 8Stop Bits: 1Echo On? NCommand file: (press ENTER, meaning that you don't want touse a script file at this point)
Baud can be anything from 300 bps to 9600 bps. It's up to you, and depends on your modem's capabilities. When done, enter "2" and press ENTER. The modem will dial the number (that you have as item 2 on the list), and try to connect. If the number is busy, you will get a warning. You can now leave Procomm (ALT+X), or set it for redialing (ALT+R). When set for redialing, Procomm will call back until a connection has been made. When CONNECT is received from your modem, Procomm announces the fact with a beep in the computer's loudspeaker. Text will start scrolling over your screen. First, a short welcome text pops up. Your interactive dialog with the bulletin board can start. The first question is "What is your First Name?" Enter your first name. Then, "What is your Last Name?" Enter your last name. Your dialog with the remote computer will continue like this. The board will ask you questions, and you will enter your answers.
What may go wrong? ————————— A setting that works beautifully when calling one bulletin board, may be a disaster when calling another service. Here are some typical problems:
When dialing through a switchboard (PBX). ————————————————————- Remember to add 9 or 0 for a city line, when dialing out from a PBX. If you forget, you'll get nowhere. Use the following command (assuming that you must enter 0 to get a city line, and use tone signaling):
If you must use 9 for a city line and pulse dialing, use the following command
Register your standard dialing command in Procomm's MODEM SETUP.Enter ALT+S and then select 1, Modem Setup. Choice 2, Dialingcommand. The default entry is ATDT. Replace this with ATDT0W,ATDP9W or whatever makes dialing work for you.
No answer from the remote computer ————————————————— Your computer has to "talk the same language" as the remote host. If the parameters of your communications program have been set incorrectly, it may be impossible to set up a connection with the service. Sometimes, you get CONNECT, but your screen only gives you strange, unintelligible 'noise' characters. The reason may be CONNECT at an incompatible speed, a service's use of special codes for displaying text (including special language characters), or that the service requires use of a special communications program or method (as when a service starts by interrogating for the use of an offline reader). Many online services require that you use certain settings. Most services, however, may be reached when using the following:
Speed: 2400 bps8 bits word length, no parity, one stop bit
Some services (notably some Unix hosts) demand 7 bits, even parity, one stop bit.
Sorry, no luck! ———————- Try again, just in case. The remote computer may have had a temporary problem, when you called. The PTT may have given you a particularly noisy telephone line on this attempt. If this doesn't help, recheck each point in the communications process. It is so easy to do something wrong. If nothing helps, read the service's user information manuals. Only rarely will you be able to blame the communications program (unless you have made it yourself), or the equipment. Most errors are caused by finger trouble and misunderstandings.
Testing the Saltrod Horror Show ———————————————- First time visitors often experience problems, and in particular if this is their first time online using a Hayes-compatible modem. Here are some typical problems with suggested solutions:
* Disable Guard Tones from the modem when dialing. If it has this feature, you can often turn it off. Put the required command in your Modem init string. * Don't press ENTER to "wake" my system. The software will automatically detect your speed and adjust accordingly. The same applies for many services. On some, you're just asking for problems by not waiting patiently (often the case when the remote software starts by checking if you use an offline reader). * My BBS accepts from 300 to 9600 bps asynchronous, full duplex communication. You may not succeed with 1200 bps half duplex, Bell 300 bps or 1200 bps. * Start with your communications program set for 8 bits word length, no parity and one stop bit. Try 7 bits, even parity if there is too much noise on the line (you cannot retrieve programs using this setting, though). * When your modem is set at a low transfer speed, it may not wait long enough for carrier from my modem. Most modems let you set this waiting time longer by giving a value to a S-register. (Read in your modem's manual about how to do this).
Partial success ———————- Some bulletin boards offer colors and music. If your equipment is set up correctly, you can receive the welcome text in full color graphics accompanied by a melody in your computer's speaker. If it is not, chances are that you will get many strange codes on your screen, and an ugly feeling that something is wrong. There are two ways out of this problem: 1. Ask the bulletin board to send text only (select U for Utilities, and then G for Graphics to change setting), 2. Set your computer for colors and graphics. This feature is only available for callers with an MS-DOS computers. You may need to add the line DEVICE=ANSI.SYS in your CONFIG.SYS. Finally, you must have a communications program that allows you to display colors on your screen. Procomm set with ANSI-BBS does that.
Downloading programs —————————— We call the transfer of programs and files from a remote computer for downloading. It means "transfer of data to your computer AND storage of the data (down) on YOUR local disk." You are downloading, when you call my board to retrieve a program. When you, overwhelmed by gratitude, send one of your favorite programs TO my bulletin board, then we call it uploading. Data can be many things. It may be news from Washington Post, a digital picture, an executable program, a pile of invoices, a piece of music, a voice file, an animated sequence of pictures and music, or compressed library files. Downloading "plain text" (also called "plain ASCII" or "DOS text" on MS-DOS machines) is relatively easy. Such text usually only contains characters between number 32 (space character) and 126 (the ~ character) in the ASCII table. Characters with lower numbers have special functions (like the control characters ESCape and CTRL+C). These may not even be displayed on your screen. Characters with higher numbers are used for graphics, special national characters, and other applications. Special transfer methods are often required, when your data contains text with characters outside ASCII number 32 through 126. Read under "Protocol transfers" below for more information about how to do this.
Downloading text ———————— Most communication programs require that you begin by opening a file. They ask you to enter a file name. From this point and onwards all incoming text will be stored in this file until you say stop. Communication programs do this in different ways. Some let incoming data flow through a temporary storage area using the principle first in, first out. When you open a file, it starts storing data from the beginning of the temporary storage area, though this text may have scrolled off your screen some time ago. Most communication programs start storing data from NOW. Procomm works this way. You start downloading of text by pressing the PgDn key. A window will appear on your screen giving you a choice between various methods. Select ASCII. In another window, you are asked to enter a file name. When done, storage of incoming data starts. You stop the process by pressing the ESC key. Procomm has another method called "file logging." You start this by pressing ALT-F1. Procomm requests the file name, and the storage process starts. (Read under "Strip" about the difference between these methods.)
If you forget to tell Procomm to store incoming data, thenyou will most probably lose this data for ever.
Do not waste time and money by forgetting to store what youreceive!
The term "append" ————————- When downloading text - or anything - it is important to know whether you are appending information to an existing file, or overwriting it (i.e., destroying the old text). Most communication programs complain with an audible signal, when you try to overwrite an existing file. They will ask you if you really want to delete it, or append the current data.
The term "strip" ———————— The purpose of 'strip' is to remove something from incoming data or to change it on the fly. When you use ASCII downloading with Procomm, ALL incoming data are being stored. This includes so-called ESCape sequences. If you use File Logging, all control characters (except the line feed and new page characters) are being removed (filtered). If you download text from a computer that uses other ASCII characters for linefeed and return, save time by having the communications program convert them on the fly to their correct form for your computer. You define strip procedures through Procomm's SetUp menu (ALT- S). You can also request automatic conversion of characters to graphics values, or local language variants.
National characters —————————- Special national characters cause problems in many countries. One reason is that they are represented by different internal codes on various hardware platforms, and that some networks are unable to transmit 8-bits data. Some systems represent these special characters by a 7-bit code, others by an 8-bit code. Some depend on the computer having an internal national language ROM, or that it uses a special (resident) conversion program. What gives good results on an MS-DOS computer, may give rubbish on a Macintosh, Amiga, Atari, or a PC using MS Windows. Many communication programs have features that can help you solve at least some these problems. They let you make translation tables for automatic conversion of special incoming and outgoing characters. If you call a Scandinavian online service using 7 bits even parity, many transfer the national special characters using the ASCII code equivalents of number 91, 92, 93, 123, 124, and 125. Similar, more or less formal standards are in place in other countries.
Protocol transfers ————————— If your purpose is to transfer digitized pictures, a computer program, a batch of invoices, a piece of music or an animated sequence of pictures, it's important that each character (bit) arrives correctly. We achieve this by using protocol transfers. These files often contain control or binary characters. You cannot transfer binary files without the use of special methods. It is easy to understand why we need protocol transfers when retrieving plain text as tables of numbers, statistics, and financial reports. Transfer errors may have fatal consequences. Protocol transfers are also required when transferring word processor text files having imbedded control codes (like text made with WordPerfect), and compressed files. Here is an example:
Downloading public domain software ————————————————— First, you need the names and features of the programs that can be downloaded from a service. On most bulletin boards, you must enter a command to navigate to the File Library. Here, they normally greet you with a menu listing available commands.
Try H (for Help!) or ? when you are stuck.
Public domain and shareware programs are stored in subdirectories on my bulletin board. The directories have numerical names. Utility programs for MS-DOS computers are stored in directory 10. Games are stored in directory 17. Enter L for a list of available directories (other bulletin boards may use different commands). Enter "L 17" to list the files in directory 17. This will give file names, lengths in characters (to help you estimate download time), creation dates, and a short description of each file. You can search for files of interest. When looking for programs that can help you get more out of a printer, you may search using keywords like "printer." Some programs are made available in text form. This is the case with older BASIC programs. (The file name extensions .BAS, .ASC or .TXT suggest that the files contain plain text.) You can download these files using ASCII. Most programs are stored in their executable form, or as one executable file among several in a compressed transfer file (a library of files). On my board, most of these files have the file name extension .EXE or .COM. What transfer protocol to use, depends on what is available in your communications program.
The protocol transfer method explained ——————————————————— The protocol transfer algorithms use methods to check the transfer with automatic error correction. In principle, they work like this: The sending program calculates a check sum based on the contents of the file. The receiving program does the same calculation and compares the result with the senders' check sum. If the figures match, the transfer was successful. If not, all or part of the file will be retransmitted. These are some popular protocols:
XMODEM ——— has automatic error detection and correction. Most modern programs have this feature. XMODEM exists in programs for MS-DOS computers, CP/M computers, Apple, TRS-80 Model 100, etc. It is the most commonly used transfer protocol. XMODEM assumes 8-bit settings in your communications program. The file to be sent is split up into 128 bit sized blocks (or "packets") before transfer. The sender calculates the check sum and adds a check sum bit at the end of each packet. (Packing, sending and checking is done automatically by the software.) The receiving program calculates its own check sum and compares with the sender's. If an error is detected, XMODEM will request retransmission of the last block. XMODEM is reasonably good when there is little noise on the telephone line is low. When the line is bad, however, there is always a chance that the transfer will stop. You cannot use XMODEM on computer networks that use ASCII flow control or ESCape codes. The transfer commands must be given to both computers. You can only transfer one file per command. XMODEM's "packet size" (block length) is short. This has an impact on transfer speed, and especially when downloading from timesharing systems, packet switched networks, via satellites, and when using buffered (error correcting) modems. The control method (8-bit check sum) and unprotected transactions give a low level of safety against errors in the transmission. The transferred file may contain 127 bytes with noise characters (at the end). The creation date of the file is lost in the transfer. These weaknesses have given us better methods. Here are some of them:
XMODEM/CRC ————— CRC is an abbreviation for Cyclical Redundancy Check. The method guarantees 99.9969 percent free transfer. It still has the other weaknesses of ordinary XMODEM transfers.
YMODEM Batch —————— is faster than XMODEM and gives a high level of safety in the transfers. When used with some programs, YMODEM can transfer the files' creation time/date. You can transfer updated documents. This will replace documents with an older creation date. Only one party must enter the file name. YMODEM takes care of the rest.
Kermit ——— is used on many computer platforms, and especially where they use a terminal emulation mode (like VT-100) which makes the use of XMODEM impossible. Kermit is one of the few asynchronous error correction protocols that functions well when exchanging files having half duplex IBM front-end machines. Kermit can transfer more than one file at the time.
Super-Kermit —————— is also called Kermit with Sliding Windows. It can transfer many packets before stopping to check the transfer. The protocol is much faster than XMODEM.
ZMODEM ——— is currently the fastest transfer protocol for many applications. All transactions are protected with a 16-bit or 32-bit CRC. ZMODEM is immune against most error conditions that prevent traditional protocols to achieve correct transfer. ZMODEM transfers the creation date of the file and its exact contents. The file name is read once, and all transfer commands may be given by the sending program.
Decompression of files ——————————— If a file has name extensions like ZIP, LZH, ARC, PAK, LQR, LBR, ZOO, ARJ, or QQQ, you are facing a compressed file. We use such files to achieve faster transfers. Files having the extension .EXE or .COM may be compressed files that have been converted into a self-extract format. To retrieve the files from a self-extract compressed file, just enter the file's name. To decompress files that have not been made self-extract, you need a utility program. These programs have many names and are available through most bulletin boards.
Transfer problems ————————- Most transfer problems are caused by the communication programs and their (lack of) features. Some Procomm users have problems with the Kermit protocol. Tip: use 8 bit world length and no parity in your program setup. 7 bits and even parity does not always work (on version 2.4.2).
Uploading ————- The transfer of data "the other way," i.e., from your disk to a remote computer, requires that you start by making some decisions. Is the file to be sent as plain ASCII? Should I compress it in a distribution file to reduce transfer time, and make it easier to handle for the recipient? If you are transferring a text file containing special national characters, then these may have to be converted to another format. If your text contains blank lines (like blank lines between paragraphs), you may have to insert a space character at the start of all such lines. Some systems interpret a blank line as a signal telling that transmission is done. The invisible space character prevents this. Some hosts have limitations on line length. They may require that lines be shorter than 80 characters. If you send lines that are too long, the result may be fatal.
Sending electronic mail ———————————- If you send your mail too fast, some online services tend to get digestion problems. You must be very accurate with the format of your message. It has to agree with the host machine's rules about line length, and maximum number of lines per message. Let's assume that you want to send the following message to an electronic mailbox:
To: Datatidcc: Anne-Tove VestfossenSj: Merry Christmas!Text: Thanks for the box with herring. The taste wasformidable. etc .. etc… etc…Greetings, Odd
If this is all you have to say, doing it manually may be as fast as doing it automatically. However, if the line containing "etc .. etc .." is two full pages of text, you may feel differently. Then, the best may be to upload a prewritten letter. Many Procomm users prefer to split the job in two. They enter the first four lines manually, and upload the body of the text (when the remote computer is ready to receive). Press PgUp to get a menu of various uploading protocols. Select ASCII for transfer of plain text. Procomm will ask for the name of the file, which contains your letter. Enter the name, and the file will be sent.
Slow down with "pacing" ———————————- Sometimes, the PgUp method is just what you need. On other days, strange things may stop you in the middle of your transfer. One typical reason is that Procomm is sending it too fast for the recipient. "Pacing" is a method used to slow the speed of the transfer to a level that the recipient can handle. Procomm lets you set a tiny pause after each line sent. Another technique is to ask the program to wait for a given character (a "Go-character"), before allowing it to send the next line. For example: the character ":" is often used in the prompts for the next line on bulletin boards.
Protocol transfers may be easier ———————————————— You may find it easier to use a transfer protocol. With Procomm, press the PgUp key, and the program will ask for a protocol. Select Kermit or something else. The program will ask for a file name, you enter it, and off it goes. You will have no problems with blank lines, or lines that are too long. At times, even this will fail. The most common reasons are: * The recipient requires that Procomm be set for 8-bits word length, no parity, 1 stop bit, when using this protocol, but you have it set differently. * You think that the recipient's version of YMODEM is the same that you have. Wrong! Total failure. Do the following to upload the file TEST.TXT to my bulletin board using XMODEM:
1. Navigate to the file area. Tell SHS what you want by usingthe following command:u;test.txt;x2. Press PgUp, select XMODEM, enter a file name (TEST.TXT), andthe transfer will start. (If you're too slow, SHS may betired of waiting for your commands . . .)3. When the transfer is completed, my board will ask for ashort description of the file. Enter it, and you're done.
Enter G (for Goodbye), and disconnect.
Appendix 4:
Explanation of some frequently used terms =========================================
We have included some terms that are commonly used in the online world. For more information, get a copy of "FYI: Internet User's Glossary." To get this file, send email to SERVICE@NIC.DDN.MIL with the following command in the Subject of your mail: RFC 1392 .
Address ———- The string of characters that you must give an electronic mail program to direct a message to a particular person. The term "Internet address" often refers to an assigned number, which identifies a host on this network.
Anonymous FTP ——————- The procedure of connecting to a remote computer, as an anonymous or guest user, to transfer files back to your computer. See FTP for more information.
ANON-FTP ———— See Anonymous FTP.
ANSI —— (1) ANSI is an organization that sets standards. (2) 'ANSI graphics' (ref. the term ANSI-BBS) is a set of cursor control codes that originated on the VT100 terminal. Many online services use these codes to help improve the sending of characters to communication programs. It uses the escape character, followed by other characters, to move the cursor on the screen, change color, and more.
Archie ——— An electronic directory service for locating information throughout the Internet. You can use Archie to locate files on anonymous ftp archive sites, other online directories and resource listings. It is useful for finding free software. Archie offers access to the "whatis" description database. This database contains descriptions that include the name and a brief synopsis of the large number of public domain software, datasets and informational documents located on the Internet. This book emphasizes email access to Archie. You can also reach archie servers by telnet to one of the following addresses:
archie.au 139.130.4.6 (Australian server) archie.mcgill.ca 132.206.44.21 (Canada) archie.funet.fi 128.214.6.100 (Finland/Europe s.) archie.th-darmstadt 130.83.128.111 (Germany) archie.cs.huji.ac.il 132.65.6.15 (Israel server) archie.kuis.kyoto-u.ac.jp 130.54.20.1 (Japan) archie.sogang.ac.kr 163.239.1.11 (Korea) archie.nz 130.195.9.4 (New Zealand) archie.ncu.edu.tw 140.115.19.24 (Taiwan) archie.doc.ic.ac.uk 146.169.11.3 (UK/England server) archie.rutgers.edu 128.6.18.15 (U.S.A.)
Archie server——————-An email-based file transfer facility offered by some systemsconnected to the Internet.
ASCII ——- The American Standard Code for Information Interchange. A standard seven-bit code created to achieve compatibility between various types of data processing equipment. ASCII, pronounced "ask-key," is the common code for microcomputer equipment. The Standard ASCII Character Set consists of 128 decimal numbers ranging from zero through 127 assigned to letters, numbers, punctuation marks, and the most common special characters. The Extended ASCII Character Set also consists of 128 decimal numbers and ranges from 128 through 255 representing additional special, mathematical, graphic, and foreign characters.
ASCII download ——————— Retrieval of plain ASCII text (without special codes). Normally, it takes place without automatic error correction, but it is typically managed by XON/XOFF flow control.
Asynchronous transfer ——————————- Serial communication between two computers. When signals are sent to a computer at irregular intervals, they are described as asynchronous. Data is sent at irregular intervals by preceding each character with a start bit and following it with a stop bit. Asynchronous transmission allows a character to be sent at random after the preceding character has been sent, without regard to any timing device. Consequently, in case of line noise, the modem can find out right away where the next byte should start.
Autodial ———— When a modem dials a telephone number automatically. Autodial may be started by the user entering the number manually, or the number may be sent automatically by the communications program (for example after having been selected from a phone register).
Baud —— A unit of measurement that shows the number of discrete signal elements, such as bits, that can be sent per second. Bits per second (bps) is the number of binary digits sent in one second. There is a difference between bps and baud rate, and the two are often confused. For example, a device such as a modem said to send at 2400 baud is not correct. It actually sends 2400 bits per second. Both baud rate and bps refer to the rate at which the bits within a single frame are sent. The gaps between the frames can be of variable length. Accordingly, neither baud rate nor bps refer accurately to the rate at which information is actually being transferred.
BBS —- Bulletin Board or Bulletin Board System. See Bulletin Board.
Bell —— Standard frequencies used in older modems made in the United States. The standard for 300 bps is called Bell 103. The standard for 1200 bps full duplex is called Bell 212A. Modems using these standards are normally unable to communicate with CCITT standard modems at these speeds.
Big5——Coding scheme developed in Taiwan for using Chinese on computers.There are different varieties of Big5 codes, the most common beingET Big5 (the code used by the Taiwanese program ETen, pronouncedYi3tian1) and HKU Big5 (the code used for programs developed atHong Kong University).ET Big5 files must be read with the ETen operating system.
Binary ——— The base 2 number system in which only the digits 1 and 0 are used is called the binary system. The binary system lets us express any number, if we have enough bits, as a combination of 1's and 0's. Also used to express conditions like on/off, true/false, yes/no.
Bits —— Bit is an abbreviation for Binary digIT. Computer words and data are made-up of bits, the smallest unit of information. A bit can be either zero or one, represented in a circuit by an off or on state, respectively. The bits are set on or off to store data, or to form a code that in turn sends instructions to the computer's central processing unit.
Bits per second (bps) ——————————- Bits per second (bps) is the number of binary digits sent in one second. It refers to the rate at which the bits within a single frame are sent ('frame' is another term for 'packet'). The gaps between frames can be of variable length. Accordingly, bps does not refer to the rate at which information is actually being transferred. We usually estimate the amount of characters transferred per second (cps) by dividing the number of bps by 10. Example: 2400 bps transfers around 240 characters per second.
Boolean ———- Search algorithm built on the algebraic theories of the English mathematician George Booles. Boolean algorithms are used in online databases to help narrow down the number of hits using the words AND, OR, and NOT.
Bounce ——— The return of a piece of mail because of an error in its delivery.
Bps —- Abbreviation for bits per second. See above.
Browse———To view and possibly edit a file of data on screen similar tohandling text in a word processing document.
Bulletin board ——————— A computer, often a microcomputer, set up to receive calls and work as an online service. The BBSes let users communicate with each other through message bases, and exchange files. They and may also offer other services (like news, data base searches, and online shopping).
Carrier———-The tone that the modem sends over a phone line before any data issent on it. This tone has a fixed frequency and a fixed amplitude.It is then modified to indicate data.
Character————-Here used about a letter, a number or another typographical symbolor code.
CCITT ——- The Consultative Committee for International Telephony and Telegraphy. An international consultative committee, organized by the United Nations. Membership includes Telephone, governmental Post, and Telegraph Authorities, scientific and trade associations, and private companies. CCITT is part of the International Telecommunications Union, a United Nations treaty organization based in Geneva, Switzerland. CCITT sets international communications recommendations. These are often adopted as standards. It also develops interface, modem, and data network recommendations. The X.25 protocol for access to packet-switched networks was originally a recommendation of CCITT. A wide range of CCITT documents is available through The Teledoc database of The International Telecommunication Union (ITU):
* CCITT and CCIR administrative documents* lists of contributions (substantive input/proposals)to CCITT and CCIR study groups* lists of CCITT reports and Recommendations(i.e., standards)* summaries of CCITT new or revised Recommendations* CCITT and CCIR meeting schedules and otherinformation concerning Study Groups structuresand activities.
For information, write to shaw@itu.arcom.ch or bautista@itu.arcom.chThe database is at teledoc@itu.arcom.ch .
COM port ———— A COM port (or communication port) is a communications channel or pathway over which data is transferred between remote computing devices. MS-DOS computers may have as many as four COM ports, COM1, COM2, COM3, and COM4. These are serial ports most often used with a modem to set up a communications channel over telephone lines. They can also be used to send data to a serial printer, or to connect a serial mouse.
Conference ————— Also called SIG (Special Interest Group), Forum, RoundTable, Echo. A conference is an area on a bulletin board or online service set up as a mini board. Most conferences have separate message bases and often also file libraries and bulletins. Conferences are focused on topics, like politics, games, multimedia and product support.
Connect time —————— A term used for the hours, minutes, and seconds that a user is connected to an online service. On several commercial services, users have to pay for connect time.
CPS —- Characters per second. See Bits per second.
Data——Information of any kind, including binary, decimal or hexadecimalnumbers, integer numbers, text strings, etc.
Database ———— A database is a highly structured file (or set of files) that tries to provide all the information assigned to a particular subject and to allow programs to access only items they need. Online services offer databases that users can search to find full-text or bibliographic references to desired topics.
DCE/DTE ———- Data Communications Equipment/Data Terminal Equipment. Equipment connected to an RS232 connector must be either a DCE (like a modem or a printer) or a DTE (computer or terminal). The term defines the types of equipment that will "talk" and "listen."
Default ———- When a value, parameter, attribute, or option is assigned by a communications program, modem, or online system unless something else is specified, it is called the default. For example, communication programs often have prespecified values for baud rate, bit size and parity that are used unless alternative values are given. These prespecified values are called the defaults. Some services give users a choice between two or more options. If a selection is not made by the user, then a selection is automatically assigned, by default.
Discussion list ———————- See Mailing list.
Domain Name System (DNS) ———————————— Email addressing system used in networks such as Internet and BITNET. The Internet DNS consists of a hierarchical sequence of names, from the most specific to the most general (left to right), separated by dots, for example nic.ddn.mil.
Doors ——- A service offered by many bulletin boards to allow the user to leave the (remote) main software system to use one or several independent programs, like games and databases.
Downloading—————-The transfer of data from an online service and "down" to yourcomputers' disk.
DTR —- Data Terminal Ready is a circuit which, when ON, tells the modem that your computer is ready to communicate. Most modems are unable to tell your computer that a connection has been set up with a remote computer before this circuit has been switched off. If your computer turns this signal OFF, while it is in a dialog with a remote computer, the modem will normally disconnect.
Duplex ——— Describes how you see text entered by the keyboard. When the setting is HALF DUPLEX, all characters entered on your computer for transfer to an online service (or your modem) will be displayed. In addition, you will normally receive an echo from the online service (or modem). The result will often 'bbee lliikkee tthhiiss'. When using the setting FULL DUPLEX, typed characters will not be shown. What you see, are characters echoed back to you from the online service and/or your modem.
ECHO —— (1) When data is being sent, the receiving device often resends the information back so the sending device can be sure it was received correctly. (2) Term used on FidoNet for this network's system of exchanging conferences (parallel conferencing).
Email ——- Abbreviation for Electronic Mail.
FAQ —- "Frequently Asked Questions" about services on the Internet. A list of FAQ documents is posted every four to six weeks to the Usenet newsgroup news.announce.newusers.
File server —————- A file server is a device that "serves" files to everyone on a network. It allows everyone on the network to get files in a single place, on one computer. Typically, it is a combination computer, data management software, and large capacity hard disk drive.
File transfer——————-The copying of a file from one computer to another over a computernetwork.
Finger ——— A program on computers directly connected to the Internet that returns information about a registered user on a system. Finger is useful before initiating chats, known on the Internet as "talk."
Flame ——- A "flame" is a conference message sent by someone who generally disagrees so violently that they are willing to sink to personal attacks. Flames can be extremely annoying, and can get the writer banished from several conference networks.
Fractal ———— A mathematical algorithm from which an image can be created. A fractal formula generates a fractal picture composed of an image based on a basic pattern. An outgrowth of chaos mathematics, it is being used for compressing and decompressing high quality images. Generally, a fractally compressed image has an extremely small file size.
FTP (File Transfer Protocol) —————————————— A program on the Internet for sending and receiving files to and from a remote computer to your local host. FTP lets you connect to many remote computers, as an anonymous or guest user, to transfer files back to your computer. FTP only lets you list file directories on foreign systems, and get or retrieve files. You cannot browse menus, send email, or search databases. Usually, type ftp at your system prompt, login on the remote system, and ask for the file you want to receive. It transfers to your local host machine. (For more on this, read under "Internet" in appendix 1.) Unless your computer is directly connected to the Internet, the retrieved software will have to be transferred from your local host machine to your PC. Where ftp is not available, you may use FTPMAIL (see chapter 12).
Full duplex —————- The term full-duplex means the transmission of data in two directions simultaneously as from a terminal to a computer or from the computer to the terminal. Full-duplex is simultaneous two-way communication.
Full-text database ————————— A database containing the full text of an article, a chapter in a book, or a book. The contents are not limited to abstracted information (indexes, bibliographic information).
FYI—-"For Your Information." On the Internet, a subseries of RFCs thatare not technical standards or descriptions of protocols.
Gateway ———- Here, we use the term gateway about an interconnection between two (or more) online services, set up to allow a user of one service to use the other service's offerings through the first service's user interface. The term also has other meanings: A gateway provides an interconnection between two networks with different communications protocols. Gateways operate at the 4th through 7th layer of the OSI model. For example, a PAD (a packet assembler/disassembler) is a device used to interface non-X.25 devices to an X.25 network. The PAD serves as a gateway. Protocol converters are gateways between networks. The gateway, provided by an adapter card in a workstation, enables the network to perform as if it were a mainframe terminal connected directly to the mainframe.
Gopher ——— A world wide information service with many implementations. It works from a top-level subject-oriented menu system that accesses other information services across the Internet. Gopher combines a finding and fetching capability in one tool. Gopher gets information from certain locations on the Internet to which it is connected, and brings the information to your computer. It can also get information via other Gophers at other locations connected to yet other hosts. The Telneting or file transfer protocols are transparent to the user. "Common Questions and Answers about the Internet Gopher" are posted to the following Usenet newsgroups comp.infosystems.gopher, comp.answers, and news.answers every two weeks. The most recent version of this FAQ is also available by anonymous ftp from rtfm.mit.edu in the /pub/usenet/news.answers directory. The file is called gopher.faq. To get it by email, write mail-server@rtfm.mit.edu with the command "send usenet/news.answers/finding-sources" in the body of the text.
GuoBiao———-Coding scheme for using Chinese on computers developed in mainlandChina. For more information, send email to LISTSERV@UGA.BITNET withone of the following commands in the text of your mail:GET PC HELP (for PC users)GET MAC HELP (Macintosh users)GET CXTERM HELP (X Windows users)
Half duplex—————-The term half-duplex means the transmission of data in eitherdirection but only one direction at a time.