Siemens Aktiengesellschaft

Winfried Glaeser

Dieter Schuett

Rudolf Holzner

Guenter Watzlawik

A control system for controlling access to a bus (BU) by a unit (P) connected to the bus (BU), including a ring circuit in which a monoflop function element and one or more coupling elements are connected in-line, each coupling element associated with a respective unit. For controlling access, a logic signal of a first type is supplied into the ring by the monoflop function element, the logic signal being successively conducted via the coupling elements to the units seeking access to the bus. Access to the bus is only allowed when the coupling element senses a transition from a logic state of the first type to a logic state of a second type at its ring circuit input.

Arrangement for the decentralized control of access to a bus by units

Connection network for the adjustable connection of a PLA

Programmable logic circuit having bidirectional data lines

A programmable circuit for carrying out logic operations on binary input signals. The programmable circuit contains a matrix of first lines crossed with second lines thereby defining intersections at which logic units corresponding to a function table are connected. Two of the first lines are combined to form a line pair. The matrix is programmed in that a logic unit is connected between one of the lines of the line pair and a second line for the binary value of '1' and a logic unit is connected between the other of the lines of the line pair and the second line for programming a binary value of '0'. Utilizing control signals, the logic units can be activated either in one direction or the other. Therefore, it is thus possible to set a line pair either as an input or as an output of the programmable circuit. When a line pair acts as an input, the binary signals coupled into the second lines by the logic units are subjected to an AND operation on the second lines. When a line pair is operated as an output, then the binary signals coupled from the second lines onto the first lines of the line pair by the logic units are subjected to a NOR operation.

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Munich, Germany

Winfried Glaeser