Browse Prior Art Database

# Keyboard Self Checking Numbering Method

IP.com Disclosure Number: IPCOM000090379D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 65K

IBM

## Related People

Marcus, MP: AUTHOR

## Abstract

This self-checking numbering system employs a logic circuit that is gated under control of the keyboard keys to-set up a combination of flip-flop states based on a decimal radix system. The logic circuit is so arranged that the outputs of the flip-flops are interconnected with the different key control gating circuits to provide a pattern of signals to the inputs of the flip-flops. The flip-flop 0 is on to indicate a valid number upon the keying of the final digit in the number. The circuit is arranged so that the output from the last flip-flop on, which is indicative of the previous sum modulo-11 of the previous keys depressed is Anded with the weight value of the present key depressed, to set the next flip-flop and reset the previous flip-flop.

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 56% of the total text.

Page 1 of 2

Keyboard Self Checking Numbering Method

This self-checking numbering system employs a logic circuit that is gated under control of the keyboard keys to-set up a combination of flip-flop states based on a decimal radix system. The logic circuit is so arranged that the outputs of the flip-flops are interconnected with the different key control gating circuits to provide a pattern of signals to the inputs of the flip-flops. The flip-flop 0 is on to indicate a valid number upon the keying of the final digit in the number. The circuit is arranged so that the output from the last flip-flop on, which is indicative of the previous sum modulo-11 of the previous keys depressed is Anded with the weight value of the present key depressed, to set the next flip-flop and reset the previous flip-flop. This checking system is adaptable to other modulo systems using other weighted values.

As in A, the matrix is based on the columns being premultiplied by the proper weighting 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 in B, all keys of the 13-column keyboard are provided with a normally open contact, one side of which is connected to a common supply that is energized when the system is placed in operation. The other sides of the contacts are commoned together according to their weighted value in the modulo-11 system to provide 10 weighted...