This book I got in a pile of FM TOWNS books turns out to be a lot more interesting that I was expecting an '80s C compiler manual to be. For as long as C and its relatives have been in mainstream use, it has been necessary to use vendor language extensions to actually get anything done with it, though in today's GCC/Clang/MSVC oligopoly those extensions tend to be focused on the yak-shaving details of dealing with the underlying platform. Things were much more interesting in the 80s, when there were a lot more, smaller companies competing for adoption. Phar Lap wrote one of the first DOS extenders that allowed programs to take full advantage of the 32-bit 80386 processor from the otherwise 16-bit-bound MS-DOS environment, and they hired MetaWare to port their High C Compiler to their SDK.
Fujitsu in turn chose Phar Lap's DOS extender to integrate into the OS for their 80386-based FM TOWNS platform, and High C became the first-party C compiler for the platform. The FM TOWNS came out in 1989, just barely in time for the first ANSI C standard C89 to be ratified. High C has its share of DOS-specific extensions, but it also contains a lot of interesting user-oriented language extensions I haven't seen in other C compilers I've used, ranging from small quality of life improvements to fairly advanced features you wouldn't think would be possible in C, let alone a late-80s dialect of C! Some of these things would take literal decades to make it into some official standard of C or C++, and some of them still don't have equivalents in either language today. Here are some of the extensions I found interesting:
If there's nothing else to take away from this amazing write up, please at the very least enjoy the goober on the front
