The story
The core open-source software was developed at MIT starting in 1982 as the PC/IP project, a project to make PCs into first-class citizens on TCP/IP networks. This project began as a Telnet implemented by Louis J. Konopelski under the supervision of Jerome Saltzer. Later contributors to the PC/IP project included John Romkey, David Bridgham, David D. Clark, and Donald W. Gillies.
FTP Software was the first of many companies to name themselves after an Internet protocol. At the time the company was founded, the PC/IP software package was already being sold by Wollongong, 3Com and others, and so some of the inventors of PC/IP decided to exploit their own product. After Donald W. Gillies produced a full-function multi-connection TCP and compatible SMTP for his bachelor's thesis, a mail proxy, it became possible to offer an FTP implementation - which requires two concurrent TCPs. This software, known as "ntcp" (new TCP) in the source tree, could support seven connections on a 128KB IBM PC-XT, and could interoperate with ten different operating systems. The multi-connection TCP languished in the source tree for two years before the FTP founders chose to make it the core of FTP Software, setting the company apart from the other competitors in this space, which were not actively improving PC/IP and were not willing to implement the FTP protocol based upon "ntcp".
From Wikipedia’s article on FTP Software, shared under CC BY-SA 4.0.4