BINARY SELECTION ENCODER

Japanese Patent JPH0884080

A

PROBLEM TO BE SOLVED: To shorten the logical propagation time of a binary selection encoder by respectively supplying high- and loworder inputs to first and second encoders and reducing delays by connecting the outputs of the encoders to bidirectional selectors of the same number as the that of the inputs of a 2-input encoder and a 2 -input encoder. SOLUTION: When one of the inputs of an encoder 92 is in an active state, a VALID output 94 is in an active state. Since the output 94 is inputted to the second input of an encoder 91, the output 94 has higher priority than an input from an encoder 90 has and, accordingly, a high-order CODE bit MSB is activated. Therefore, it can be discriminated that which one of the encoders 90 and 92 is activated. Other CODE bits 96-96i and 97-97i are selected from the CODE output of the encoder 90 or 92. Since these CODE bits discriminate one of 2 pieces of inputs, one is selected as a low-order bit and, when the encoder 92 has an active input, the CODE bit of the encoder 92 is selected. When the encoder 92 has no active input, the CODE bit of the encoder 90 is selected.