Long ago, I bought the MIX C compiler for DOS. It had a tendency to miscompile basic things like the ++ operator. Lost hours of my life on it.

One day I found out about DJGPP, and even if the download cost a fortune in phone time, life was so much better.

Now the C reference book included with MIX C turned out to be much better than the compiler itself, and served me well for a decade.