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91/91a-1991 - IEEE Standard Graphic Symbols for Logic Functions (Including and incorporating IEEE Std 91a-1991, Supplement to IEEE Standard Graphic Symbols for Logic Functions)

Description: An international language by which it is possible to determine the functional behavior of a logic or circuit diagram with minimal reference to supporting documentation is defined; as such, it is designed to allow a single concept to be expressed in one of several different ways, according to the demands of a particular situation. Consequently, this standard does not attempt, nor intend, to establish single correct symbols for particular devices. The symbols for representing logic functions or devices enable users to understand the logic characteristics of these functions or devices without specific knowledge of their internal characteristics. Definitions and an explanation of symbol construction are provided. Information is presented on: qualifying symbols associated with inputs, outputs, and other connections; dependency notation; combinational and sequential elements; and symbols for highly complex functions. The symbols and representation techniques are compatible with IEC Pub. 617, Part 12.Supplement Abstract: Graphic symbols for representing logic functions or physical devices capable of carrying out logic functions are presented. Descriptions of logic functions, the graphic representation of these functions, and examples of their applications are given. The symbols are presented in the center of electrical applications, but most may also be applied to nonelectrical systems (for example, pneumatic, hydraulic, or mechanical). This supplement provides additional internationally approved graphic symbols and makes corrections as needed to IEEE Std 91-1984.
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