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Phasor card: in native mode, writes to SSI263 regs 0,1 & 2 all clear the SSI263 IRQ. (#1197)

This commit is contained in:
tomcw 2024-04-13 13:23:10 +01:00
parent b00c9b0d3f
commit 664d7c2d86
1 changed files with 20 additions and 19 deletions
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39
source/SSI263.cpp
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@ -127,6 +127,7 @@ BYTE SSI263::Read(ULONG nExecutedCycles)
{
// Regardless of register, just return inverted A/!R in bit7
// . inverted "A/!R" is high for REQ (ie. Request, as phoneme nearly complete)
// NB. this doesn't clear the IRQ
return MemReadFloatingBus(m_currentMode & 1, nExecutedCycles);
}
@ -140,6 +141,25 @@ void SSI263::Write(BYTE nReg, BYTE nValue)
ssiRegs[nReg] = nValue;
#endif
// Notes:
// . Phasor's text-to-speech playback has no CTL H->L
// - ISR just writes CTL=0 (and new ART+AMP values), and writes DUR=x (and new PHON)
// - since no CTL H->L, then DUR value doesn't take affect (so continue using previous)
// - so the write to DURPHON must clear the IRQ
// . Does a write of CTL=0 clear IRQ? (ie. CTL 0->0)
// . Does a write of CTL=1 clear IRQ? (ie. CTL 0->1)
// - SSI263 datasheet says: "Setting the Control bit (CTL) to a logic one puts the device into Power Down mode..."
// . Does phoneme output only happen when CTL=0? (Otherwise device is in PD mode)
// SSI263 datasheet is not clear, but a write to DURPHON must clear the IRQ.
// . Empirically writes to regs 0,1 & 2 all clear the IRQ (and writes to 3,4..7 don't) (GH#1197)
// NB. For Mockingboard, A/!R is ack'ed by 6522's PCR handshake and D7 is cleared.
if (m_cardMode == PH_Phasor && nReg <= SSI_RATEINF)
{
CpuIrqDeassert(IS_SPEECH);
m_currentMode &= ~1; // Clear SSI263's D7 pin
}
switch(nReg)
{
case SSI_DURPHON:
@ -151,25 +171,6 @@ void SSI263::Write(BYTE nReg, BYTE nValue)
SSI_Output();
#endif
// Notes:
// . Phasor's text-to-speech playback has no CTL H->L
// - ISR just writes CTL=0 (and new ART+AMP values), and writes DUR=x (and new PHON)
// - since no CTL H->L, then DUR value doesn't take affect (so continue using previous)
// - so the write to DURPHON must clear the IRQ
// . Does a write of CTL=0 clear IRQ? (ie. CTL 0->0)
// . Does a write of CTL=1 clear IRQ? (ie. CTL 0->1)
// - SSI263 datasheet says: "Setting the Control bit (CTL) to a logic one puts the device into Power Down mode..."
// . Does phoneme output only happen when CTL=0? (Otherwise device is in PD mode)
// SSI263 datasheet is not clear, but a write to DURPHON must clear the IRQ.
// NB. For Mockingboard, A/!R is ack'ed by 6522's PCR handshake.
if (m_cardMode == PH_Phasor)
{
CpuIrqDeassert(IS_SPEECH);
}
m_currentMode &= ~1; // Clear SSI263's D7 pin
m_durationPhoneme = nValue;
Play(nValue & PHONEME_MASK);