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Hall Effect Keyboard having Read Only Shift Register

IP.com Disclosure Number: IPCOM000076410D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Counihan, RG: AUTHOR

Abstract

This apparatus implements an electronic keyboard with a minimum module and pin count, utilizing low-cost interconnection techniques and eliminating a separate read-only storage (ROS).

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Hall Effect Keyboard having Read Only Shift Register

This apparatus implements an electronic keyboard with a minimum module and pin count, utilizing low-cost interconnection techniques and eliminating a separate read-only storage (ROS).

As shown, this electronic keyboard system is based on Hall effect key modules integrated with personalized read-only shift registers (ROSR) to generate the desired coded outputs. Several different modes of operation are possible.

First, if a continuously running clock is assumed, then depressing any key activates the shift register in that key module which cycles through once and stops. The first bit out is sensed to set a data ready condition to the system. Shift, or mode, control of the keyboard selects the correct byte of six-nine bits out of a possibility of four or more to send to the system. A single output buffer in the keyboard, either serial or parallel holds the last character keyed. Repeating action functions are accomplished by a time delay from a "dot-OR" of the +F lines connecting repeating action keys.

In the alternative, assuming a gated clock in order to save power, then the output terminal of a given key rises when the key is depressed. This also activates the ROSR which normally dissipates no power in its quiescent state. The rise of the output point triggers an exact burst of clock pulses. The repeating action functions are performed as in the previous described case. This second mode of operation is analogous...