Introduced by Intel in 1971, the MCS-4 system included the 4004 CPU, the 4001 ROM, the 4002 RAM, and the 4003 I/O expander.
It was a 4-bit microprocessor, capable of handling binary and decimal arithmetic.
The system supported conditional branching, jump to subroutine, and indirect fetching.
It had a 10.8-microsecond instruction cycle and could directly drive up to 32,768 bits of ROM and 5,120 bits of RAM.
The MCS-4 paved the way for the microprocessor revolution, despite its complicated memory architecture.