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Browse Prior Art Database

Keyboard Self Checking Numbering Method

IP.com Disclosure Number: IPCOM000090377D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Marcus, MP: AUTHOR

Abstract

This self-checking switching matrix that is controlled by key-operated switches can be employed with any type keyboard and modulo system. When a given key is depressed, a modulo-11 counter is employed and is incremented according to the proper modulo-11 weight of the given key. When all keys are scanned, a 0 modulo-11 count exists in the counter, providing the inserted number is a valid number.

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Keyboard Self Checking Numbering Method

This self-checking switching matrix that is controlled by key-operated switches can be employed with any type keyboard and modulo system. When a given key is depressed, a modulo-11 counter is employed and is incremented according to the proper modulo-11 weight of the given key. When all keys are scanned, a 0 modulo-11 count exists in the counter, providing the inserted number is a valid number.

As shown at A the matrix is based on the columns being premultiplied by the proper weighing factor in the modulo-11 system. For example, the weighted number for key 8 in digit column 5 and 11 is 7. Likewise, weighted number 4 in digit columns 6 and 12 is indicative of key 8.

Drawing B includes free-running oscillator 1 that is continually stepping along eleven-position weight ring 2 that is cycling repeatedly from T...0. Each time ring 2 reaches 0, column ring 3 is advanced one position in a descending order from
13...1. Ring 2 is gated to stop at weight 0 column 1 and is gated to reset and start upon receipt of an external start signal. Ring 2 is a closed type. Ring 3 is of the open type. The output pulse from ring 2, in addition to advancing ring 3, also resets latch 4. The outputs of all key And's are fed to Or 5 whose output is fed to latch 4 to turn it on. When latch 4 is on, And pulses from the oscillator enter modulo-11 counter 7 via And 6. These pulses advance counter 7 by the weighted value of the key depressed. Each key is...