74F382

The 74F382 performs three arithmetic and three logic operations on two 4-bit words, A and B. Two additional Select (S0S2) input codes force the Function outputs Low or High. An overflow output is provided for convenience in Two's Complement arithmetic.

A carry output is provided for ripple expansion. For high-speed expansion using a carry look-ahead generator, refer to the 74F381 data sheet.

Signals 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 Function Table. The circuit 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. Ripple expansion is illustrated in Figure 1. The overflow output OVR is the Exclusive-OR of Cn+3 and Cn+4; a High signal on OVR indicates overflow in Two's complement operation (See Table 2 for Two's complement arithmetic). Typical delays for Figure 1 are given in Table 1. When the 74F382 is cascaded to handle word lengths longer than 4 bits, only the most significant overflow (OVR) output is used.