To make the SID chip play a note, we must know what frequency matches that note. Natural notes are the white keys on a piano keyboard, sharp notes are the black ones. Sharp notes may be seen as detuned notes used to make melodies richer. That means, seven “full” notes (natural notes) and five sharp notes. On each octave we have twelve half tones.
The A5 note, an A note on the fifth octave, has a frequency which doubles the frequency of A4 instead. The A3 note, which is an A note on the third octave, has a frequency that is half the frequency of A4, that is, 220 Hz. Usually, notes frequencies are referred to A4, the A note on the fourth octave, which has a frequency of 440 Hz. We can compute the frequency of any note by starting from the frequency of a particular note that we are using as a reference. In other words, the frequency is the pitch of a sound. The higher the frequency, the higher the sound. I’ve already introduced musical notes and very rough music theory concepts on the Goattracker tutorials, so if you need to dust off such topics please refer to them.Įach note on a piano keyboard has its own frequency. Nothing very exciting, but many concepts are required even for this very basic task. But if you are interested on actually coding what you are hearing, then this article may be of help. I’ve already provided you with some tutorials dealing with composing C64 music with Goattracker.
Although machine language is what we really need for C64 music programming, BASIC may be more than acceptable for some experiments on SID music programming.Īs Commodore 64 BASIC V2 doesn’t provide specialised commands for music, SID music programming using this interpreter is just a matter of POKE instructions.
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