The Intel 4004 was the first commercially available microprocessor. It contained 2,300 transistors and integrated the central processing unit, memory, and input/output controls onto a single chip for the first time. The 4004 had a maximum clock speed of 740 kHz and could perform between 46,300 to 92,600 instructions per second. It used a 4-bit architecture with instructions and data transferred over a single multiplexed bus.