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Invalid Code Print Suppress

IP.com Disclosure Number: IPCOM000075526D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Battistoni, R: AUTHOR [+2]

Abstract

In the Hollerith code commonly used on key entry devices, some codes represent letters, numbers or punctuation marks that are to be printed, but for some codes there are no corresponding printable characters. The circuit of the drawing produces an output on a line 2 to suppress a print operation when an invalid code is detected.

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Invalid Code Print Suppress

In the Hollerith code commonly used on key entry devices, some codes represent letters, numbers or punctuation marks that are to be printed, but for some codes there are no corresponding printable characters. The circuit of the drawing produces an output on a line 2 to suppress a print operation when an invalid code is detected.

Each data code is made up of 12 bits that appear serially on a line 3 at bit times T25 through T36. The 12 bits of a code are commonly designated 12, 11, and 0 through 9. A large portion of the invalid codes are characterized by two or more bits in positions 1 through 7 and 9. Codes having only one of these bits are valid. Certain codes having combinations of bits 12, 11, 0 and 8 are valid and others are invalid.

An OR Invert circuit 4 responds to timing and data signals representing bits 12, 11, 0 and 8 and produces an output in which a logical 1 signifies that the data on line 3 corresponds to bits 1 through 7 and 9. An AND circuit 5 receives the output of circuit 4 and the data on line 3 to produce an output for each logical 1 in bit positions 1 through 7 and 9. Two trigger circuits 6 and 7 count the outputs of circuit 5 and produce an input to an OR circuit 9 that appears as the invalid code signal on line 2, whenever a code has this invalid combination of bits. A signal on line 8 at bit time T19 resets triggers 6 and 7 for the next code. As the drawing shows, certain other combinations of bits 12, 11, 0 an...