Abstract: An emulator that emulates the operation of a target machine on an execution machine is disclosed. The execution module prepared for each function of the target machine is called via a dispatcher from a kernel. A calling address is registered in a dispatcher table by the execution module when each execution module is loaded. Inputs from a keyboard causes a hardware interrupt resulting in the calling of a keyboard emulator. After a converted key code is stored in a buffer, an interrupt controller emulator is called by intermodule communication. The interrupt controller emulator requests a virtual interrupt for the kernel. The keyboard emulator is called again and the key code stored in the buffer is transmitted to the application program.