Browse Prior Art Database

Self-Test for a Keyboard/Display Unit

IP.com Disclosure Number: IPCOM000061238D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Hightower, SA: AUTHOR

Abstract

A detached keyboard/display unit has a self-test sequence in which keys on the keyboard are each tested separately, display commands on the display are tested, an audible feedback is tested, and an Intel 8051 microprocessor, which controls the keyboard/display unit, is tested. In a self-test mode, the Intel 8051 microprocessor polls the keyboard with key breaks being discarded as can be observed from the flow chart. The test uses all of the hardware (keyboard, display, and beeper) in the same fashion as in normal system operation. If the test works at all, this provides verification that the microprocessor is functioning normally. If the "pip" (beeper) is heard, this verifies that the audible feedback is functioning normally. This is found in the first portion on the left side of the flow chart prior to the self-test mode.

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Self-Test for a Keyboard/Display Unit

A detached keyboard/display unit has a self-test sequence in which keys on the keyboard are each tested separately, display commands on the display are tested, an audible feedback is tested, and an Intel 8051 microprocessor, which controls the keyboard/display unit, is tested. In a self-test mode, the Intel 8051 microprocessor polls the keyboard with key breaks being discarded as can be observed from the flow chart. The test uses all of the hardware (keyboard, display, and beeper) in the same fashion as in normal system operation. If the test works at all, this provides verification that the microprocessor is functioning normally. If the "pip" (beeper) is heard, this verifies that the audible feedback is functioning normally. This is found in the first portion on the left side of the flow chart prior to the self-test mode. If any key is stuck in its closed position or its contacts are dirty, no display occurs when the key button is depressed. This indicates that the depressed key button is the cause of the trouble. Each key made has a different unique eight-bit field stored in memory and represented in the display command by a two-digit hexadecimal code. If any hex code is not displayed, it will be noticed. The display command is tested on the right side of the flow chart. If the display command is not executed, it will not appear. Reset occurs when power is off and comes on. Timer interrupt occurs at time periods during oper...