The National MAPS (Microprogrammable Arithmetic Processor System) or National MM570x was a family of multi-chip bit-serial microcontrollers designed by National Semiconductor. The system was made of 5 discrete chips designed to operate on variable-sized words. The system can be programmed to operate in binary or BCD up to a 76 bit one cycle data word. The chipset was marketed as a general purpose serial data microcomputer system. The chipset was introduced in late 1971 but was quickly replaced within a few short years.