| 摘要 |
PURPOSE:To suppress increase of the storage capacity and complication of the circuit by executing a musical sound generating program at each sampling time of musical sound generation. CONSTITUTION:Timer interrupt is adopted for the purpose of executing the musical sound generating program in a control ROM at intervals of a prescribed time. An interrupt handling program is started at intervals of a certain time by an interrupt control part having a timer. Musical sound waveform data is sent to a D/A converter each time when data is inputted to the interrupt, and a simple of musical sounds is periodically given. Channel processing consists of envelope processing and waveform processing. In the waveform processing, phase data which indicates the phase of the waveform and consists of an integer part and a decimal part is generated, from pitch data indicating the frequency of musical sounds. The integer part of the address is used to read out waveform data in two adjacent addresses from a waveform ROM, and a waveform value imagined for the address indicated by (integer part)+(decimal part) is obtained by interpolation. The range is extended by this interpolation. |
