public void set_chip_model(SIDDefs.chip_model model) { if (model == SIDDefs.chip_model.MOS6581) { // The mixer has a small input DC offset. This is found as follows: // // The "zero" output level of the mixer measured on the SID audio // output pin is 5.50V at zero volume, and 5.44 at full // volume. This yields a DC offset of (5.44V - 5.50V) = -0.06V. // // The DC offset is thus -0.06V/1.05V ~ -1/18 of the dynamic range // of one voice. See Voice.java for measurement of the dynamic // range. mixer_DC = -0xfff * 0xff / 18 >> 7; f0 = f0_6581; f0_points = f0_points_6581; f0_count = f0_points_6581.Length; } else { // No DC offsets in the MOS8580. mixer_DC = 0; f0 = f0_8580; f0_points = f0_points_8580; f0_count = f0_points_8580.Length; } set_w0(); set_Q(); }
public void set_chip_model(SIDDefs.chip_model model) { voice0.set_chip_model(model); voice1.set_chip_model(model); voice2.set_chip_model(model); filter.set_chip_model(model); extfilt.set_chip_model(model); }
public void set_chip_model(SIDDefs.chip_model model) { if (model == SIDDefs.chip_model.MOS6581) { // Maximum mixer DC output level; to be removed if the external // filter is turned off: ((wave DC + voice DC) * voices + mixer DC) * volume // See Voice.cs and Filter.cs for an explanation of the values. mixer_DC = ((((0x800 - 0x380) + 0x800) * 0xff * 3 - 0xfff * 0xff / 18) >> 7) * 0x0f; } else { // No DC offsets in the MOS8580. mixer_DC = 0; } }
public void set_chip_model(SIDDefs.chip_model model) { if (model == SIDDefs.chip_model.MOS6581) { wave__ST = memWave6581.wave6581__ST; wave_P_T = memWave6581.wave6581_P_T; wave_PS_ = memWave6581.wave6581_PS_; wave_PST = memWave6581.wave6581_PST; } else { wave__ST = memWave8580.wave8580__ST; wave_P_T = memWave8580.wave8580_P_T; wave_PS_ = memWave8580.wave8580_PS_; wave_PST = memWave8580.wave8580_PST; } }
public void set_chip_model(SIDDefs.chip_model model) { wave.set_chip_model(model); if (model == SIDDefs.chip_model.MOS6581) { // The waveform D/A converter introduces a DC offset in the signal // to the envelope multiplying D/A converter. The "zero" level of // the waveform D/A converter can be found as follows: // // Measure the "zero" voltage of voice 3 on the SID audio output // pin, routing only voice 3 to the mixer ($d417 = $0b, $d418 = // $0f, all other registers zeroed). // // Then set the sustain level for voice 3 to maximum and search for // the waveform output value yielding the same voltage as found // above. This is done by trying out different waveform output // values until the correct value is found, e.g. with the following // program: // // lda #$08 // sta $d412 // lda #$0b // sta $d417 // lda #$0f // sta $d418 // lda #$f0 // sta $d414 // lda #$21 // sta $d412 // lda #$01 // sta $d40e // // ldx #$00 // lda #$38 ; Tweak this to find the "zero" level // l cmp $d41b // bne l // stx $d40e ; Stop frequency counter - freeze waveform output // brk // // The waveform output range is 0x000 to 0xfff, so the "zero" // level should ideally have been 0x800. In the measured chip, the // waveform output "zero" level was found to be 0x380 (i.e. $d41b // = 0x38) at 5.94V. wave_zero = 0x380; // The envelope multiplying D/A converter introduces another DC // offset. This is isolated by the following measurements: // // * The "zero" output level of the mixer at full volume is 5.44V. // * Routing one voice to the mixer at full volume yields // 6.75V at maximum voice output (wave = 0xfff, sustain = 0xf) // 5.94V at "zero" voice output (wave = any, sustain = 0x0) // 5.70V at minimum voice output (wave = 0x000, sustain = 0xf) // * The DC offset of one voice is (5.94V - 5.44V) = 0.50V // * The dynamic range of one voice is |6.75V - 5.70V| = 1.05V // * The DC offset is thus 0.50V/1.05V ~ 1/2 of the dynamic range. // // Note that by removing the DC offset, we get the following ranges // for // one voice: // y > 0: (6.75V - 5.44V) - 0.50V = 0.81V // y < 0: (5.70V - 5.44V) - 0.50V = -0.24V // The scaling of the voice amplitude is not symmetric about y = 0; // this follows from the DC level in the waveform output. voice_DC = 0x800 * 0xff; } else { // No DC offsets in the MOS8580. wave_zero = 0x800; voice_DC = 0; } }