Changes
Willy - [[MIDI ]] and OPL3 Soundcard adapter for CPC
It is the spiritual successor of the [[CPCISA]] project.
* [https://opl.wafflenet.com/ The OPL archive] [https://vgmrips.net/packs/chip/ym3812 VGMrips OPL2] [https://vgmrips.net/packs/chip/ymf262 VGMrips OPL3]
* [http://tgv777.free.fr/index.php/fichiers-midi/ MIDI Files] [https://musical-artifacts.com/artifacts?order=most_downloaded&q=midi+soundfont MIDI SoundFonts]
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*[https://www.serdashop.com/CVX4 CVX4 soundcard] aka Covox Speech Thing - [https://scalibq.wordpress.com/2017/11/28/the-covox-years/ Technical analysis]
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== I/O Ports ==
2 ports are used to control the [[MIDI ]] soundcard: &FEAC for data, and &FEAD for control and status.
3 ports are used to control the OPL3 soundcard: &FEBC and &FEBE are register select ports, and &FEBD is the data port.
When such a table is used for calculation of the exponential, the table is read at the position given by the 8 LSB's of the input. The value + 1024 (the hidden bit) is then the significand of the floating point output and the yet unused MSB's of the input are the exponent of the floating point output.
==== Log-sin Logsin table ====
x = 0..255, y = round(-log(sin((x+0.5)*pi/256/2))/log(2)*256)
