- My language of choice is C and I am currently getting more involved with the CP/M operating system. I have therefore decided that it would be nice to have a C compiler working under CP/M. There are a number of options available in the archives, but I have found that HI-TECH are allowing their CP/M C Compiler to be downloaded for free. This is a very good product, has good documentation, is almost ANSI C compliant and can be used for commercial and non-commercial use. This, therefore, is the one I have chosen.