R! (Ring Indicator)

This may be confusing, but we are stuck with it. In any case, as long as you know the pinout you can make a working cable—the signals are the same.

Why Asynchronous?

You have probably heard the 1enn before, maybe in its shortened form of "async/ but what does it mean? Async refers to the fact that characters sent over the connection will not necessarily arrive at any particular time. This is important because the receive station must somehow decode the incoming signal, and to do that it needs to know when the character starts and ends. This is where the notion of start and stop bits comes from. These allow the receiving equipment to determine the front and back of the transmitted characters. When you set your communications parameters to; a data bits no parity 1 stop bit you are specifying the structure of each character sent. One stop bit will be sent—a start bit is always sent. The parity bit is used—or rather not used— for error detection, Though this is its intended purpose, it is rarely done,

I am going to stop here with Part 1. Part 2, next month, will finish this discussion—with the final installment ccv-

Conlinued on page 50


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