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AY-3-8910:
* Fixed Gyruss audio regression * Measured RU and RD on AY-3-8910 * Modelled ZX Spectrum audio circuit in SwitcherCAD and derived resistor values for AY-3-8910
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@ -287,7 +287,8 @@ static const ay_ym_param ay8910_param =
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/*
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* RL = 2000, Based on Matthew Westcott's measurements from Dec 2001.
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*
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* -------------------------------------------------------------------
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*
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* http://groups.google.com/group/comp.sys.sinclair/browse_thread/thread/fb3091da4c4caf26/d5959a800cda0b5e?lnk=gst&q=Matthew+Westcott#d5959a800cda0b5e
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* After what Russell mentioned a couple of weeks back about the lack of
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* publicised measurements of AY chip volumes - I've finally got round to
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@ -316,14 +317,19 @@ static const ay_ym_param ay8910_param =
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* 13 2.06
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* 14 2.32
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* 15 2.58
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* -------------------------------------------------------------------
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*
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* The ZX spectrum output circuit was modelled in SwitcherCAD and
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* the resistor values below create the voltage levels above.
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* RD was measured on a real chip to be 8m Ohm, RU was 0.8m Ohm.
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*/
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static const ay_ym_param ay8910_param =
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{
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1030, 357,
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800000, 8000000,
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16,
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{ 81509, 34403, 26998, 21248, 15890, 11495, 8625, 5314,
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4287, 2583, 1836, 1350, 978, 745, 530, 392 }
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{ 15950, 15350, 15090, 14760, 14275, 13620, 12890, 11370,
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10600, 8590, 7190, 5985, 4820, 3945, 3017, 2345 }
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};
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/*************************************
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@ -869,8 +875,10 @@ int ay8910_read_ym(void *chip)
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if (r > 15) return 0;
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/* FIXME: calling stream_update here makes gyruss sound awfull.
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* For the time being, no idea why this is the case */
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/* update the output buffer before returning the register */
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stream_update(psg->channel);
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/* stream_update(psg->channel); */
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switch (r)
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{
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