Question

what is accumulator of ALU​

Answer 1

An accumulator is a register for short-term, intermediate storage of arithmetic and logic data in a computer's CPU (central processing unit). The term "accumulator" is rarely used in reference to contemporary CPUs, having been replaced around the turn of the millennium by the term "register."

Answer 2

In a computer's central processing unit (CPU), the accumulator is a register in which intermediate arithmetic and logic results are stored. ... Modern computer systems often have multiple general purpose registers that operate as accumulators, and the term is no longer as common as it once was.