Need C information for IBM PC

[Gregory Kenley]

We are in the process or writing software that will have to run both
on Vax/750's and IBM-PC's in the language C.  Since there are numerous 
implementations of C for the IBM PC we were wondering if anyone had some
insight as to which IBM-PC implementation is closest to Berkeley's 4.2 Unix
C compiler.  I have been told that implementations tend to vary with refards
to the completeness of the standard libraries.  You comments are appreciated.