Browse Prior Art Database

Automatic Carriage Conrol Handling for Start/Stop Lines

IP.com Disclosure Number: IPCOM000075873D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Bolk, TF: AUTHOR [+2]

Abstract

A communications multiplexer is described in IBM System Reference Library Manual "IBM 2969 Programmable Terminal Interchange Model 1, RPQ 88117: Special Feature Description", Order Number GL22-6940-0, copies of which may be obtained from any IBM Branch Office or by writing IBM Product Publication, Department B98, P. O. Box 390, Poughkeepsie, New York, 12602.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 3

Automatic Carriage Conrol Handling for Start/Stop Lines

A communications multiplexer is described in IBM System Reference Library Manual "IBM 2969 Programmable Terminal Interchange Model 1, RPQ 88117: Special Feature Description", Order Number GL22-6940-0, copies of which may be obtained from any IBM Branch Office or by writing IBM Product Publication, Department B98, P. O. Box 390, Poughkeepsie, New York, 12602.

A specific code (6A) from the communications lines translate tables is used to indicate an invalid input or output data code, and is used in lieu of a parity check on line data. Detection of this invalid data code causes the termination of receive or transmit operation and an interrupt to the software is generated.

Additional use is made of this feature for carriage control function transmission to 2740/1050 type terminals.

In order to properly transmit carriage control functions such as new line, carriage return, line feed, horizontal tab and vertical tab, idle characters must be inserted into the data stream following the function. This is to allow the terminal hardware time to perform the function so that succeeding data characters are not printed as the carriage function is being performed. A typical output message with a new line function in it would appear in storage as follows:

(Image Omitted)

Input messages that typically come from a terminal on a start/stop line include carriage control characters. The hardware at the terminal forces the delay required and does not send characters that cause idle characters to be stored. A typical input message would appear in storage as follows:

(Image Omitted)

In order to send the message indicated as MSG2 in a start/stop line, it would have to be edited to look like MSG1. This not only requires the storage for the original message but additional storage for the new message that will be generated.

Circuits in the...