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Technique for Testing Communicating Device in Non-Native Environment

IP.com Disclosure Number: IPCOM000044571D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Blair, BE: AUTHOR [+3]

Abstract

This article describes a technique which provides a self-test capability for a display unit when the unit is not running in its native environment. A test-mode pattern (which may include an invalid character set, etc.) is generated and forwarded to the communicating port of the unit. On recognizing the pattern, the unit automatically switches to a test mode. Thereafter, the test pattern is applied to the unit to test each character in the display. The data pattern is provided by a simple square wave. The display unit receives data as a result of the square wave, and the sequence of data caused by the square wave will not be available to the unit when the unit is running in its native environment.

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Technique for Testing Communicating Device in Non-Native Environment

This article describes a technique which provides a self-test capability for a display unit when the unit is not running in its native environment. A test-mode pattern (which may include an invalid character set, etc.) is generated and forwarded to the communicating port of the unit. On recognizing the pattern, the unit automatically switches to a test mode. Thereafter, the test pattern is applied to the unit to test each character in the display. The data pattern is provided by a simple square wave. The display unit receives data as a result of the square wave, and the sequence of data caused by the square wave will not be available to the unit when the unit is running in its native environment. Also, with a square- wave input the display can be plugged into a test rack randomly with respect to each other and each display will go into self-test mode as soon as it sees a predetermined number of transitions in the square wave. When the display is running in its native environment, the display communicates at 187.5 bits/second using a 12-bit start-stop asynchronous data format. When driven by a square wave of frequency 10.42 KHz the display will receive nine consecutive 0 bits followed by nine consecutive 1 bits. The nine 0 bits break down into a start bit followed by 8 data bits, and the nine 1 bits break down into a control bit followed by 8 stop bits. The display perceives a square wave to be a...