The Intel 4004 was the first commercially available microprocessor in history released by Intel Corporation in 1971. The 4004 was a 4-bit CPU designed for use in the Busicom 141-PF printing calculator. The chip, which clocked at 740 KHz, employed a 10µm process silicon-gate, capable of executing 92,000 instructions per second. The chip was capable of accessing 4KB of program memory and 640 bytes of RAM. The 4004 was part of the Intel MCS4 system.

The microprocessor had a limited architecture such as only 3-levels deep stack, a complex memory access scheme, and no interrupt support.