The first public mention of 4004 was an advertisement in the 15 November 1971 edition of "Electronic News". The first delivery was to Busicom for their engineering prototype calculator in March 1971, followed by their 141-PF prototype calculator commercially available in the market in July 1971. Packaged in a 16-pin ceramic dual in-line package, the 4004 was the first commercially available computer processor designed and manufactured by chip maker Intel, which had previously made semiconductor memory chips. The chief designers of the chip were Federico Faggin, the leader of the project after the architectural definition was finalized with Busicom, who created the design methodology and the silicon-based chip design; Ted Hoff who formulated the architecture, both of Intel, and Masatoshi Shima of Busicom who assisted in the development.