An emulator technology for correctly adapting a processing capability of an entertainment apparatus according to the contents requested by software. An emulator is incorporated in an entertainment apparatus without processing capability adjusting means, such as a personal computer operating system. The emulator judges through a determination section whether the software executed by the entertainment apparatus has requested a change of the processing capability of the apparatus, and if it is judged that the software has requested a change of the processing capability, the emulator makes it possible to change the processing capability of the entertainment apparatus within a range identified by predetermined change parameters supplied for the software in advance or afterward.