Q: How can I do serial (``comm'') port I/O?
A: It's system-dependent. Under Unix, you typically open, read, and write a device file in /dev, and use the facilities of the terminal driver to adjust its characteristics. (See also questions 19.1 and 19.2.) Under MS-DOS, you can use the predefined stream stdaux, or a special file like COM1, or some primitive BIOS interrupts, or (if you require decent performance) any number of interrupt-driven serial I/O packages. Several netters recommend the book C Programmer's Guide to Serial Communications, by Joe Campbell.