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Browse Prior Art Database

Self-Checking Number Circuit

IP.com Disclosure Number: IPCOM000098178D
Original Publication Date: 1960-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Roe, JU: AUTHOR

Abstract

Prior to their entry into a machine under keyboard control, pulses representing numerals are self-checked by the circuits shown. A number such as 72 would carry a check digit 7. Using base 11 the check digit is developed by deriving the 11's complement of the units digit and all alternate digits. The complement digits and uncomplemented digits are crossadded. The sum is subtracted from the next higher multiple of 11 plus 1.

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Self-Checking Number Circuit

Prior to their entry into a machine under keyboard control, pulses representing numerals are self-checked by the circuits shown. A number such as 72 would carry a check digit 7. Using base 11 the check digit is developed by deriving the 11's complement of the units digit and all alternate digits. The complement digits and uncomplemented digits are crossadded. The sum is subtracted from the next higher multiple of 11 plus 1.

The circuit acts in reverse adding first 7 then the complement of 2 which is effected by actuating the substitution relay. This adds a 9. The check digit 7 is then added. If the number has been correctly entered, the relay 1 operates closing a signal circuit (not shown) permitting entry of the number.

Control of the check circuit is by the substitution relay 10 which is actuated on alternate cycles by a cam 11. In entering the 7 a circuit is traced from battery in a keyboard or other entry means over lead 12 through the normally closed #7 contacts of relays 10, 8, 4, 2 and 1, over leads 14, 15 and 16 to ground energizing relays 18, 19 and 20. These relays lock up to ground under control of cam 21. A cam contact 22 energizes relays 4, 2 and 1 through the outer normally open, now closed contacts of relays 18, 19 and 20. Relays 4, 2 and 1 lock up to ground under control of cam 23. Entry of digit 2 closes a circuit from battery, lead 25, N/O now closed #2 contact of relay 10, lead 26, N/C #9 contact of relay 8, N/O now closed #9 contact of relay 4, lead 27, N/O now closed #2 contact of relay 2, lead 28, N/O now closed #4 contact of relay 1, lead 30...