It was successful among hobbyists in late 1970s in Japan, due to its reasonable price and an expensive computer terminal not being required.

NEC started as a telecommunications equipment vendor, and their business was heavily dependent on Nippon Telegraph and Telephone Public Corporation (NTT).

To increase private demand and exports, NEC began developing new industries such as computers and semiconductors in the 1950s.

In Japan, few engineers were interested in microprocessors, and NEC salesmen couldn't find what kind of demand would make much profit.

At the same time, NEC received an order from a laboratory in the Yokosuka Communication Institute of NTT that they wanted an educational microcomputer product for their new employees.

Tomio Gotō (後藤 富雄), a member of the section, proposed to Watanabe developing an educational kit.

[1][2] Based on this kit, the TK-80 was developed for general engineers and aimed to create a demand for microprocessors outside the industrial field.

He decided to document its manual with a circuit diagram and assembly code of the debug monitor, influenced by the PDP-8 which was an open architecture and was used as an IC tester at NEC.

NEC had opened a support center (Bit-INN) at the Akihabara Radio Kaikan on September 13, 1976.

Watanabe and his members wrote an introductory book Mi-com Introduction (マイコン入門) in July 1977, it became very popular and sold more than 200,000 copies.

Around the same time, a third party manufacturer suggested an expansion board to provide TV output and a BASIC interpreter.