Difference between revisions of "PSG"
| Line 1: | Line 1: | ||
[[Category:PSG]] | [[Category:PSG]] | ||
| − | + | Various PSGs were used in the Intellivision from the AY-3-891x family, including the AY-3-8914, AY-3-8916 and AY-3-8917. | |
| + | |||
| + | The text below is just a bunch of notes for now, to be organized into something meaningful eventually. | ||
| + | |||
| + | Clock speed is 3579545/16 (223721.5625 Hz) | ||
| − | + | ==Registers== | |
| + | |||
| + | |||
| + | ==Channels== | ||
| + | square wave output optionally modified by the envelope generator and/or the noise generator | ||
| + | Volume (0-15) | ||
| + | Period (1-4096) | ||
| + | Tone Enabled | ||
| + | Envelope Enabled | ||
| + | Noise Enabled | ||
| + | |||
| + | 16 volume levels, independent to each channel | ||
| + | |||
| + | if (channel.toneEnabled || channel.noiseEnabled) { | ||
| + | if ( | ||
| + | channel | ||
| + | } | ||
| + | else | ||
| + | channel.output = ; | ||
| + | channel0.output = | ||
| + | (((channel0.toneDisabled | channel0.tone) & | ||
| + | (channel0.noiseDisabled | noise)) | ||
| + | ? (channel0.envelope ? envelopeVolume | ||
| + | : channel0.volume) : 0); | ||
| + | |||
| + | ==Envelope Generator== | ||
| + | Period | ||
| + | Atak, Cont, Hold, Altr | ||
| + | Volume (0-15) | ||
| + | 16-bit period value multiplied by two, from 2 PSG clock cycles to $20000 | ||
| + | |||
| + | |||
| + | ==Noise Generator== | ||
| + | The random noise generator adheres to the following formula once per PSG clock cycle. | ||
| + | |||
| + | noise = (noise >> 1) ^ ((noise & 1) ? 0x14000 : 0); | ||
| + | |||
| + | The lowest bit resulting from this calculation is used to add noise to any channel with noise enabled. | ||
Revision as of 23:57, 19 January 2005
Various PSGs were used in the Intellivision from the AY-3-891x family, including the AY-3-8914, AY-3-8916 and AY-3-8917.
The text below is just a bunch of notes for now, to be organized into something meaningful eventually.
Clock speed is 3579545/16 (223721.5625 Hz)
Registers
Channels
square wave output optionally modified by the envelope generator and/or the noise generator Volume (0-15) Period (1-4096) Tone Enabled Envelope Enabled Noise Enabled
16 volume levels, independent to each channel
if (channel.toneEnabled || channel.noiseEnabled) {
if (
channel
}
else
channel.output = ;
channel0.output =
(((channel0.toneDisabled | channel0.tone) &
(channel0.noiseDisabled | noise))
? (channel0.envelope ? envelopeVolume
: channel0.volume) : 0);
Envelope Generator
Period Atak, Cont, Hold, Altr Volume (0-15) 16-bit period value multiplied by two, from 2 PSG clock cycles to $20000
Noise Generator
The random noise generator adheres to the following formula once per PSG clock cycle.
noise = (noise >> 1) ^ ((noise & 1) ? 0x14000 : 0);
The lowest bit resulting from this calculation is used to add noise to any channel with noise enabled.
