conio.h header file contains a large set of functions that do screen
and keyboard I/O. The functions will write directly to the screen or poll the
keyboard directly with no more help from the operating system than needed.
This has some disadvantages, but on the other side it's fast and reasonably
portable. conio implementations exist for the following targets:
The conio.h header file does also include the system specific header files which define constants for special characters and keys.