Email 101 Part 13

0,1, or 2 STOP BITS. 1 stop bit is the usual setting these days.

If your modem has its speaker on, you will here a dial tone, then the modem will dial, and then there will be a lot of squeals as the two computers "negotiate" about the transmission. If you are lucky, both computers will establish a "carrier" tone or hum that is then modulated to send data. At this point most modems turn of the speaker, but a "carrier detect" light should be on. As long as you have the carrier you have the connection. The carrier is present--to your modem, at least--even if you tell your software to "go off line" for a while. If you hang up, however, the carrier is dropped.

Now that you have a carrier, whatever you type is sent to the other computer (and the "transmit" light flashes), and you can receive data as well. Pay attention to any banner the service you are connecting to may print. In particular you need to know what "escape character" your system recognizes. Typing this character or sequence of characters allows you to stop tranmitting everything and give your own system a command. This is especially important if are transferring a file and have to "escape back to your own system" to tell it what to do with the incoming data.

FIRST STEPS ON A NEW SYSTEM

Many services let you sign up by connecting your computer to a

TRANSFERRING DATA

Getting data from one computer to another is a matter of running *two*

programs--one on each computer. These programs use a common protocol, or procedure, to communicate. The most common protocols are XMODEM, YMODEM, ZMODEM, and KERMIT (for UNIX systems and some others). The steps involved--using KERMIT as an example--are:

1. Run KERMIT on the sending machine

2. Escape to the receiving machine

3. Run KERMIT on the recieving machine

4. Wait for the transfer to finish.

You will have to read your software manual for more specific instructions, unless you have a direct internet connection or SLIP connection. In these cases you can issue a File Transfer Protocol (FTP) command to whichever computer and the details at the other end are automatically taken care of. See Chapter X for more detail on transferring data.

DISCONNECTING

You will want to use whatever "logoff" procedure the remote computer wants. If your manual or other literature doesn't tell you, and you can't get any information by trying "help" or "?", try the following commands: "logout", "logoff", "lo", "bye", "exit", "quit".

If all else fails you can drop the carrier using the "hangup" command (or escape back to your system and send "ATH" to your modem--attention, hangup).

As a last resort pull the plug and your telephone company will disconnect you, then exit your software and turn off your computer.

You may have to get your modem's attention by typing the "escape sequence", which varies from modem to modem or connection to connection.

Technical Details of Internet Connections

[This chapter is under construction]

Just enough UNIX

Since the UNIX operating system may be unfamiliar to many of you, and since many workstations on the net use UNIX, it may help some readers to summarize some of the peculiarities of UNIX. One day you may be logged on to a UNIX machine. Nowadays, like many operating systems, UNIX hides behind a graphical user interface like the X Windows system.

Occasionally--and networking is unfortunately one of those occasions-- its quirks like file-naming and directory hierarchy peek through.

This Appendix gives you just enough UNIX to avoid some pitfalls and issue commands needed to transfer files. The basic commands you need to know for any system are how to display directories and list the contents of files, how to name files, and how to get help about the system. UNIX commands are just as quirky as MS-DOS, VMS, RSX, VM, or any other operating system that uses a command language. Fortunately, they are no harder.