Even, Odd, or No PARITY. One way to check for errors in transmission is to tag each byte with a bit that means "even or odd", the parity bit. If a bit is transmitted incorrectly, then the parity bit won't agree with byte sent and the software can ask for that byte or block of data again. NO parity is the most common setting today, however.
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