A compatibility adapter device comprising: an external connection interface (202, 201) configured to be connected to an external connection terminal of a new-generation entertainment device; a compatibility processor unit configured to be compatible with a processing function of an old-generation entertainment device; a control unit configured to receive data, which has been input to the new-generation entertainment device, from the new-generation entertainment device via the external connection interface (202, 201), the control unit being configured to receive from the new-generation entertainment device input data from a recording medium via the external connection interface (202, 201), in response to the new-generation entertainment device determining that the recording medium is of an old-generation type storing application software for the old-generation entertainment device; the control unit being configured to cause the compatibility adapter device to process said input data by providing the received input data to the compatibility processor unit for subjecting to a compatibility process which includes graphics rendering; the control unit being further configured to subsequently transmit back to the new-generation entertainment device via the external connection interface (202, 201) the data processed by the compatibility processor unit, wherein one or more frames rendered by the compatibility processor unit are skipped in order to cancel displacement in the cycles of frames due to difference in the clock frequencies of the new-generation entertainment device and the old-generation entertainment device; and an emulator unit configured to demodulate a reproduced pre-demodulation signal read from the recording medium, wherein, when the type of the recording medium storing application software is for the old-generation entertainment device, the control unit receives the reproduced pre-demodulation signal that has been read from the recording medium in the disk drive of the new-generation entertainment device from the new-generation entertainment device via the external connection interface (202, 201), supplies the received signal to the emulator unit, and supplies the data demodulated by the emulator unit to the compatibility processor unit. an external connection interface (202, 201) configured to be connected to an external connection terminal of a new-generation entertainment device; a compatibility processor unit configured to be compatible with a processing function of an old-generation entertainment device; a control unit configured to receive data, which has been input to the new-generation entertainment device, from the new-generation entertainment device via the external connection interface (202, 201), the control unit being configured to receive from the new-generation entertainment device input data from a recording medium via the external connection interface (202, 201), in response to the new-generation entertainment device determining that the recording medium is of an old-generation type storing application software for the old-generation entertainment device; the control unit being configured to cause the compatibility adapter device to process said input data by providing the received input data to the compatibility processor unit for subjecting to a compatibility process which includes graphics rendering; the control unit being further configured to subsequently transmit back to the new-generation entertainment device via the external connection interface (202, 201) the data processed by the compatibility processor unit, wherein one or more frames rendered by the compatibility processor unit are skipped in order to cancel displacement in the cycles of frames due to difference in the clock frequencies of the new-generation entertainment device and the old-generation entertainment device; and an emulator unit configured to demodulate a reproduced pre-demodulation signal read from the recording medium, wherein, when the type of the recording medium storing application software is for the old-generation entertainment device, the control unit receives the reproduced pre-demodulation signal that has been read from the recording medium in the disk drive of the new-generation entertainment device from the new-generation entertainment device via the external connection interface (202, 201), supplies the received signal to the emulator unit, and supplies the data demodulated by the emulator unit to the compatibility processor unit.