MC54/74F381

Signals MC54/74F381 applied to the Select inputs S0S2 determine the mode of operation, as indicated in the Function Select Table. An extensive listing of input and output levels is shown in the Truth Table. The MC54/74F381 performs the arithmetic functions for either active-HIGH or active-LOW operands, with output levels in the same convention. In the Subtract operating modes, it is necessary to force a carry (HIGH for active-HIGH operands, LOW for active-LOW operands) into the Cn input of the least significant package.

The Carry Generate (G) and Carry Propagate (P) outputs of MC54/74F381 supply input signals to the F182 carry lookahead generator for expansion to longer word length, as shown in Figure 1. Note that an F382 ALU is used for the most significant package. Typical delays for Figure 1 are given in Figure 2.