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Browse Prior Art Database

SNA/SDLC to ASCII/ Start Stop Converter

IP.com Disclosure Number: IPCOM000048219D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Keefe, DD: AUTHOR [+2]

Abstract

This article describes a microprocessor controlled unit that connects to a System Network Architecture/ Synchronous Data Link Control (SNA/SDLC) interface on the upstream side and to a number of ASCII/START-STOP terminals on the downstream side.

This text was extracted from a PDF file.
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SNA/SDLC to ASCII/ Start Stop Converter

This article describes a microprocessor controlled unit that connects to a System Network Architecture/ Synchronous Data Link Control (SNA/SDLC) interface on the upstream side and to a number of ASCII/START-STOP terminals on the downstream side.

The figure shows controllers 10 and 12 connected, respectively, by a loop 14 and a combination of a so-called teleprocessing (TP) line 16 and a modem 18 to a host system 20. Each of the controllers 10, 12 serves one or a number of ASCII/START-STOP terminals 22 via respective adapters 24 in the controllers.

The terminals 22 may be keyboard displays or printers or any mix of the two. Each of the controllers 10, 12 includes a microprocessor, read only storage (ROS) for its program, and read-write random-access memory (RAM) for working registers and data storage (not individually shown). Adapters 24 receive and store one byte (one character) of information each and provide the conventional echo discipline for communication between controller 10 or 12 and the individual terminals 22. If desired, the adapters could buffer more than one character, but single character storage in the adapters is adequate where the operation of the terminals 22 is totally asynchronous and the traffic is to be distributed among a number of terminals as shown.

The loop 14 and line 16 traffic are in accordance with SNA/SDLC which is converted to ASCII/START-STOP format for the terminals 22 by the controllers 10, 12.

In use, host 20 places a message on loop 14 addressed to one of the terminals 22. This message is converted and outputted to the addressed terminal 22. At the same time. end without conflict, keystrokes at any of the other terminals 22 attached t...