 However, few utilities were ultimately written in B because it was too slow, and B could not take advantage of PDP-11 features such as byte addressability.In 1972, Ritchie started to improve B, which resulted in creating a new language C. The C compiler and some utilities made with it were included in Version 2 Unix.At Version 4 Unix, released in November 1973, the Unix kernel was extensively re-implemented in C. By this time, the C language had acquired some powerful features such as codice_11 types.