Referring to The Development of C Language: A History of C written by Dennis M. Ritchie, the basic process of the birth of C language was that Ken Thomson was not satisfied with BCPL, so he designed B language, wrote a compiler for B language together with BCPL, and then bootstraps a new B language compiler from this compiler. Everyone in Bell Labs wrote all kinds of things in B language on PDP-7, and then they were dissatisfied with B language. So at 197 1, DMR began to write an extension from B to B on the newly bought PDP- 1 1, which is called NB (new B, some words are omitted here), and this extension is getting farther and farther away from B's painting style. 1In the summer of 973, they rewrote a Unix kernel for PDP- 1 1 with the compiler and language at hand. C language was formed around this period.

So it can be said that the first C language compiler was written in B language, or an extended B language (n B). Because snowballing with an improved compiler while improving the language is also written in C language? After all, it is difficult to determine when C itself will become a new language. ...