Browse Prior Art Database

Keyboard Self Checking Numbering Method

IP.com Disclosure Number: IPCOM000090376D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 70K

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. This particular example utilizes a modulo-11 summing method in which each number keyed includes a precalculated check digit in the units position. When the number is entered correctly, a specific path in the circuit matrix is established by the appropriate contacts on the key-operated switches. However, when the number is incorrectly keyed, a circuit path is not established through the contacts and an error signal is indicated. The self-checking system is self-contained and requires no external counters, adders, accumulators or associated equipment.

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 2

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. This particular example utilizes a modulo-11 summing method in which each number keyed includes a precalculated check digit in the units position. When the number is entered correctly, a specific path in the circuit matrix is established by the appropriate contacts on the key-operated switches. However, when the number is incorrectly keyed, a circuit path is not established through the contacts and an error signal is indicated. The self-checking system is self-contained and requires no external counters, adders, accumulators or associated equipment.

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

As shown in B by the partial keyboard circuit, column 1 has only one normally open contact per key. However, the output from each key is connected to a separate contact on each key in column 2. Since there are 10 keys in column 1, keys 9...1 in column 2 require ten normally open contacts per key. The key 0, not normally operated, has a total of 10 normally closed contacts. The connections of the outgoing circuits from key column 2 are connected to key column 3, etc., across the...