4-Bit Arithmetic Logic - Fairchild Semiconductor
Description
DM74LS181 4-Bit Arithmetic Logic Unit
October 1988 Revised April 2000
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
s Provides 16 arithmetic operations: add, subtract, compare, double, plus twelve other arithmetic operations s Provides all 16 logic operations of two variables: exclusive-OR, compare, AND, NAND, OR, NOR, plus ten other logic operations s Full lookahead for high speed arithmetic operation on long words
Ordering Code:
Order Number DM74LS181N Package Number N24A Package Description 24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-010, 0.
600 Wide
Logic Symbols
Active High Operands
Connection Diagram
Active Low Operands
Pin Descriptions
Pin Names A0–A3 B0–B3 S0–S3 M Cn F0–F3
VCC = Pin 24 GND = Pin 12
Description Operand Inputs (Active LOW) Operand Inputs (Active LOW) Function Select Inputs Mode Control Input Carry Input Function Outputs (Active LOW) Comparator Output Carry Generate Output (Active LOW) Carry Propagate Output (Active LOW) Carry Output
A=B G P Cn+4
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DM74LS181
Functional Description
The DM74LS181 is a 4-bit high speed parallel Arithmetic Logic Unit (ALU).
Controlled by the four Function Select inputs (S0–S3) and the Mode Control input (M), it can perform all the 16 possible logic operations or 16 different arithmetic operations on active HIGH or active LOW operands.
The Function Table lists these operations When the Mode Control input (M) is HIGH, all internal carries are inhibited and the device performs logic operations on the individual bits as listed.
When the Mode Control input is LOW, the carries are enabled and the device performs arithmetic operations on the two 4-bit words.
The device incorporates full internal carry lookahead and provides for either ripple car...
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