AW: Arithmetic and logical unit.

• It is widely used and popular combination circuit.

• It is capable of performing the arithmetic as well as logical operator.

• AW is heart of any microprocessor.

$Ao - A3$

$\beta o - \beta3$ ope and i/ps

$S_o – s_3 \rightarrow$ Function select i/ps

$M \rightarrow$ mode control bit

$Fo – F3 \rightarrow$ function o/p

$ A = B \rightarrow$ comparator o/p

$ G \rightarrow$ carry generator o/p

P $\rightarrow$ carry propagate o/p

$C_n + 4\rightarrow$ carry o/p.

IC – 74181 can perform total 18 atheistic operations which includes addition, sub, comparator and double operations, etc.

• It provides many logical operations such that AND, OR, NOR, NAND, etc.

• It is high speed 4 bit parallel AW.

$m = 0$ , performs arithmetic operations.

$m = 1$, performs logical operator.

G & P o/ps are used when a number of 74181 are to use in cascade along with lock ahead carry generator.