In a central processing unit, a special register, or memory location, in which the temporary results of calculations are stored. Without an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory and read them back. Access to main memory is slower than access to the accumulator, which is generally built right in to the processor. An example is the commonly used Motorola 56000 series of DSP chips, which utilize 24-bit processing and have two 56-bit accumulators built in.