Abstract: A floating-point arithmetic system, which allows arithmetic operations, including at least addition and subtraction, to be performed for floating-point data. The system includes multiple-input addition and subtraction devices for executing adding and subtracting calculations of at least three floating-point data. Preferably, the multiple-input addition and subtraction devices includes a multiple-input device which enables at least three floating-point data to be input, a shift-amount determining device having a look up table which compares the respective exponents in parallel, selects the maximum exponent and determines the amount of shift in the respective mantissas; and a mantissa shifting devices, e.g., at least one multiplexer, which shifts the respective mantissas in accordance with the amount of shift and makes an adjustment of digit positions of the mantissas.

Abstract: A communication control device receives and transmits control data and/or communication data through a ring communication network. The apparatus comprises a wait time decision unit for deciding, according to a state of the network, a wait time for detecting a reception of the control data circulating through the network; a wait time holding unit for holding the wait time decided by the wait time decision unit; and a time counting unit for counting time from a reception of the control data and providing a broken control data report signal if the control data is not again received within the wait time.