74LS181 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 
■ Provides 16 arithmetic operations: add, subtract, compare, double, plus twelve other arithmetic operations 
■ Provides all 16 logic operations of two variables: exclusive-OR, compare, AND, NAND, OR, NOR, plus ten other logic operations 
■ Full lookahead for high speed arithmetic operation on long words

Here's another quick design by Bits. Once a week I select a TTL from the Multisim (74ls) section and have a go at whatever looks interesting. 
So today's TTL is the 74ls181. Please note I am currently a student so these designs are a little amateur, however I will do my best to present them neatly. 

• The M input selects whether the ALU should calculate logical functions (M=1) or arithmetic functions (M=0)

             Pin Names & Functions 

1. A0-A3, B0-B3: Operand (Active LOW) inputs
2. S0-S3: Function - Select Inputs
3. M: Mode Function Input
4. Cn: Carry Input
5. F0-F3: Function (Active LOW) Outputs
6. A=B: Comparator Output
7. G: Carry Generator (Active LOW) Output
8. P: Carry Propagate (Active LOW) Output
9. Cn+4: Carry Output

What I have learned about the 74ls181 is that it is capable of performing all the 16 different logic operations when using two inputs. That's like having a big 74lsXX series TTL all rolled into one! This TTL looks like it will come in very handy. For now my circuit friends, I have only played with the HEX display and counted up/down using the top and middle dip switches. The highest hex value was F, a 15 in decimal numbers.  

My goal is to make more advanced circuits using the 74ls181 and share them with you. 


  

74ls181.ms13
File Size:	158 kb
File Type:	ms13

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