Posted By
TLC
on 2009-09-11
05:26:14
|  Re: MUSIC ON TED (for programmists)
The answer should be divided to two parts -- depending on how you generate the sounds.
1.) You use the TED sounds natively (no artifical sound generation ie. digis)
2.) You write your own sound engine that generates, mixes and plays waveforms.
I guess you were referring to 1.). Keeping that in mind, the answers are
1.) Nope. Noise can be played on channel 2, and exclusively (either square wave, or noise). Channel 1 can't play noise waveform.
2.) "No" and "Yes". The noise waveform is hardwired, but you can change the speed at it is played (similarly to AY but the waveform appears to be shorter thus more "periodic").
3.) There's no volume envelope logic in the TED (at all). The volume setting is a "global volume" that applies to both sound generators at the same time. If you set volume 0, both sound channels mute immediately. If you set volume 8, both would play at the highest volume level (provided that they were turned on first) immediately.
It might be simpler if I summarize what and how you can set in the TED sound registers. This is pretty simple (nowhere near the complexity of the AY).
-- Two 10-bit "frequency" registers (one for each channels) -- better said, it's rather "T" than "f" (you don't describe frequency but period of time, similarly to the AY in principle). The lowest possible frequency that you can generate is about 110Hz.
-- One 4-bit global volume (levels from 0 to 8 are defined, 9 to 15 maps to volume level 8).
-- One on/off bit for each channels. The second channel has a noise on/off bit, too.
-- One "force reload" bit for the whole sound generator (with which one can reset the whole mechanism, and play digis using the volume register).
That's all. No envelopes, no independent volume levels etc.
-----> Edit: you can of course use volume envelopes if they are provided by the music player, but you only have one, global volume to apply settings on. And another thing to add: the volume levels of the TED are linear-ish, as opposed to the AY, where they're exponential.
I am / have been really interested in your results.
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