Chapter 3 SERIAL PORTS

The configuration and use of serial ports is 3 complex matter. You must keep in mind a large number of detail; and you must observe complicated procedures exactly We have tried to reduce the amount of technical detail in this chapter, giving only sufficient detail to show the structure and effect of commands and how they relate to each other. The supportive detail will be found in the Appendices. Once you are familiar with capabilities of the Interface Module, you will probably make most frequent reference to the Appendices \NEED 9; SPACE 5 Overview

(Wondering what that crap is at the end of the paragraph? I have no idea. It was in the Manual, so I just left it there!) --Eric

The RS-~32-C standard defines a range of values of parameters of a communication link. This is described more fully in APPENDIX 1. The ATARI ATARI e50 interface Module is the device used in ATARI Personal Computer Systems to set the values of these parameters. The Interface Module organizes the bit stream of communication according to the software-coded interactions.

When we refer to a communication port as an RS-232-C port, we mean that signals to/from that port conform to the RS-232-C standards. We also use the adjective "RS-232-C-~ompatible': when the communication conforms to essential aspects of the RS--232-C standard, with the implication that the channel may lack some features of the standard and may incorporate other features not included in the standard. Perhaps the most important aspect of the standard is the specification of voltage levels corresponding to mark and space. Accordingly, many other publications may use the term "RS-232-C-compatible" to mean "using the voltage levels in the RS-232-C standard".

Using software instructions to set the particular standard or "protocol" is called "configuring the port". In configuring the port you may set the following:

Baud

1.

• Number of bits per word sent/received
• Number of stop bits per word sent
• Whether the incoming control signals DSR, CTS and CRX are monitored
• Whether input parity is checked
• Whether output parity is set

2.

• Whether Line Feed is added after every Carriage Return sent
• Translation of the word being sent or received (3 types of translation)

3. Whether the outgoing control signals DTR, RTS are used

These are shown as three groups, corresponding to the three configuration commands; otherwise, the division into groups is arbitrary.

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