Question

Explain the function of ALU with a simple block diagram.

Explain the organization of ALU with the help of block diagram.

Answer 1

The organization of arithmetic and logic unit is shown in the figure.

1. The arithmetic and logic unit is an 8-bit unit.
2. The ALU contains: 
   1. Adder
   2. Shifter
   3. Status register
3. It performs arithmetic, logic and rotates operations.
4. It consists of the binary adder to perform addition and subtraction by 2’s complement method.
5. The result is typically stored in an accumulator.
6. Accumulator, temporary register and flag register are closely associated with A.L.U.
7. The temporary register is used to hold data during an arithmetic/logic operation.
8. The flags are set or reset according to the result of operations in the status register.