While skimming did I miss an example of code that is portable between most of these systems? I'd love to see that because I'm having a very hard time believing

While skimming did I miss an example of code that is portable between most of these systems? I'd love to see that because I'm having a very hard time believing that's possible. Or maybe you can make something that will technically compile and function on any of those, but if it doesn't perform reasonably then it's really hard to call the portability aspect a success. Also you're very limited as to what you can actually do in ANSI C. You're going to need to start poking directly at the hardware which is not going to be portable. Hell, even stuff like checking if a letter is within a certain range in the English alphabet might not work between machines. Letters might not be contiguous in the machine's native character encoding.