Page "B (programming language)" Paragraph 4

The typeless nature of B made sense on the Honeywell, PDP-7 and many older computers, but was a problem on the PDP-11 because it was difficult to elegantly access the character data type that the PDP-11 and most modern computers fully support.

Starting in 1971 Ritchie made changes to the language while converting its compiler to produce machine code, most notably adding data typing for variables.

During 1971 and 1972 B evolved into " New B " and then C, with the preprocessor being added in 1972 and early 1973 at the urging of Alan Snyder.

The effort was sufficiently complete that during the summer of 1973 the Unix kernel for the PDP-11 was rewritten in C. During the 1972 – 73 period there was a need to port to Honeywell 635 and IBM 360 / 370 machines, so Mike Lesk wrote the " portable I / O package " which would become the C " standard I / O " routines.