74LS181 DIP 4-Bit Arithmetic Logic Unit and Function Generator
The 74LS181 is a highly complex TTL integrated circuit that functions as a 4-bit Arithmetic Logic Unit (ALU) and function generator. It is capable of performing 16 different arithmetic operations and 16 different logic operations on two 4-bit words. Arithmetic operations include addition, subtraction, and comparison, while logic operations cover AND, OR, NAND, NOR, and XOR. The specific function is determined by four binary select inputs and a mode control input.
This IC features a full internal look-ahead carry for high-speed arithmetic operations and is designed to be easily cascadable to handle larger word lengths. When the mode control is high, logic functions are performed on the individual bits; when it is low, arithmetic operations are performed on the two 4-bit words. Its versatility made it a foundational component in the central processing units (CPUs) of early computers and it remains a key device for educational digital logic and complex data processing projects.
KEY FEATURES
- 16 binary arithmetic operations including addition and subtraction
- 16 logic functions including XOR, AND, and OR
- Full look-ahead carry for high-speed arithmetic
- Can be cascaded for n-bit word lengths
- Mode control input to switch between logic and arithmetic
- Standard 24 pin dual in line package
SPECIFICATIONS
- Supply Voltage 4.75V to 5.25V
- Operating Temperature 0 to 70 Celsius
- Logic Type TTL Low Power Schottky
- Typical Addition Time 24ns
- Typical Logic Shift Time 13ns
- High Level Output Current -0.8mA
- Low Level Output Current 16mA
- Input Voltage High 2.0V Minimum
INTERFACES
- A0 to A3 4-bit data inputs word A
- B0 to B3 4-bit data inputs word B
- S0 to S3 Function select inputs
- M Mode control input
- CN Carry input
- F0 to F3 Function outputs
- A=B Comparator output
- G Carry generate output
- P Carry propagate output
- CN+4 Carry output
- VCC Positive supply voltage
- GND Ground reference
