History of Microcontrollers: First 50 Years
K. Raghu Raghunathan · IEEE Micro · 2021
To understand the impact of microprocessors and controllers one must dial back 50 years to when the computing machine that was most often seen was the store point-of-sale cash registers, which were popularized by the NCR Corporation. In the early 1960s, the integrated circuits (ICs) integration was making a steady progress from small to medium to large scale (SSI, MSI, LSI) densities and mostly standard products. The improvement in process technology brought in the era of very large-scale ICs with metal–oxide–semiconductor (MOS) devices and custom chip design. In 1971, Intel announced the 4004,1 the industry's first 4-bit microprocessor.