© 2000 Fairchild Semiconductor Corporation DS009821 www.fairchildsemi.com
October 1988
Revised April 2000
DM74LS181
4-
Bit
Ari
t
h
m
e
t
i
c
Logi
c Uni
t
DM74LS181
4-Bit Arithmetic Logic Unit
General Description
The DM74LS181 is a 4-bit Arithmetic Logic Unit (ALU)
which can perform all the possible 16 logic operations on
two variables and a variety of arithmetic operations.
Features
a73 Provides 16 arithmetic operations: add, subtract, com-
pare, double, plus twelve other arithmetic operations
a73 Provides all 16 logic operations of two variables:
exclusive-OR, compare, AND, NAND, OR, NOR, plus
ten other logic operations
a73 Full lookahead for high speed arithmetic operation on
long words

Ordering Code:
Logic Symbols
Active High Operands
Active Low Operands
V
CC
= Pin 24
GND = Pin 12
Connection Diagram
Pin Descriptions
Order Number Package Number Package Description
DM74LS181N N24A 24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-010, 0.600 Wide
Pin Names Description
A0–A3 Operand Inputs (Active LOW)
B0–B3 Operand Inputs (Active LOW)
S0–S3 Function Select Inputs
M Mode Control Input
C
n
Carry Input
F0–F3 Function Outputs (Active LOW)
A = B Comparator Output
G Carry Generate Output (Active LOW)
P Carry Propagate Output (Active LOW)
C
n+4
Carry Output