When transferring waveform data from a waveform region in a high-capacity flash memory to a waveform buffer in a RAM, first, whether a non-ring buffer region that can receive the waveform data can be allocated in the RAM is determined, and if so, the waveform data is transferred to the allocated non-ring buffer region. If such a non-ring buffer region cannot be allocated, then whether a ring buffer region that can receive the waveform data can be allocated in the RAM is determined, and if so, the waveform data is transferred to the ring-buffer region in a ring buffer operational manner.