Allows hooking of interrupts (software and hardware) into classes, comes with classes for staying resident, for serial communication (interrupt driven), and like-wise classes. Comes with full source code! Is DOS specific (current version works only under BC++ 3.0 and higher).
This class in PD, current version for registered users is version 4.
ftp from oak.oakland.edu in /pub/msdos/cplusplus or /pub/msdos/cluspls ?