04014016 is referenced by 7 patents and cites 4 patents.

A sightless indicating system and method is disclosed that is useful as an indicating device for diverse equipment, including equipment such as an electronic calculator, and is particularly useful by a blind person. When utilized as a part of an electronic calculator, a standard calculator keyboard is modified to include a sign key and an output key so that an operator can initiate output indications and determine the sign of such indications in addition to initiating the customary numerical and function inputs. The customary numerical and function inputs are processed in conventional manner except that the calculator output is converted to a sightless indicating form, such as audible signals indicative of output. For an audible indication of the modified calculator, the output key is depressed and the value of each digit to be indicated is converted to a series of equally spaced output tones at substantially the same frequency with a different number of tones being utilized for each digit to differentiate therebetween. In addition, a steady, low-level output tone is utilized to indicate a decimal point in the audible output of a calculator, while an output tone of the same frequency as that used to indicate digits is utilized to indicate the sign of the output when the sign key on the keyboard is depressed. Manual or automatic sequencing modes can be selected and in the automatic sequencing mode, the output key need be depressed only once for indication of all digits whereas in the manual mode, the output key must be depressed for each digit to be indicated with leading zeros being suppressed in either operational mode.

Audio indicating system
Application Number
Publication Number
Application Date
November 29, 1974
Publication Date
March 22, 1977
Joseph A Eccher
Jay G Sherritt
O Rourke Harris & Hill
Ball Brothers Research Corporation
G08B 3/10
G08C 19/22
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