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Phasor/MB (#1192) 

. For MB: isChipSelected[0] = true. So do this on Reset() or for Phasor when switching to MB mode.
. Add "Notes on Phasor's AY-3-8913 chip-select & r/w"
. Refactor some common code into SY6522::UpdatePortAForHiZ()
This commit is contained in:
tomcw 2023-03-05 15:37:52 +00:00
parent 7110e92f14
commit 500f32071b
4 changed files with 46 additions and 11 deletions
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7
source/6522.cpp
View File

@ -116,6 +116,13 @@ USHORT SY6522::SetTimerSyncEvent(BYTE reg, USHORT timerLatch)
//-----------------------------------------------------------------------------
void SY6522::UpdatePortAForHiZ(void)
{
BYTE ora = GetReg(SY6522::rORA);
ora |= GetReg(SY6522::rDDRA) ^ 0xff; // for any DDRA bits set as input (logical 0), then set them in ORA
SetRegORA(ora); // empirically bus floats high (or pull-up?) if no AY chip-selected (so DDRA=0x00 will read 0xFF as input)
}
void SY6522::UpdateIFR(BYTE clr_ifr, BYTE set_ifr /*= 0*/)
{
m_regs.IFR &= ~clr_ifr;

1
source/6522.h
View File

@ -28,6 +28,7 @@ public:
void StopTimer2(void);
bool IsTimer2Active(void) { return m_timer2Active; }
void UpdatePortAForHiZ(void);
void UpdateIFR(BYTE clr_ifr, BYTE set_ifr = 0);
void UpdateTimer1(USHORT clocks);

43
source/Mockingboard.cpp
View File

@ -92,6 +92,7 @@ MockingboardCard::MockingboardCard(UINT slot, SS_CARDTYPE type) : Card(type, slo
for (UINT i = 0; i < NUM_SUBUNITS_PER_MB; i++)
{
m_MBSubUnit[i].nAY8910Number = i;
m_MBSubUnit[i].Reset(QueryType());
const UINT id0 = i * SY6522::kNumTimersPer6522 + 0; // TIMER1
const UINT id1 = i * SY6522::kNumTimersPer6522 + 1; // TIMER2
m_MBSubUnit[i].sy6522.InitSyncEvents(m_syncEvent[id0], m_syncEvent[id1]);
@ -177,6 +178,29 @@ void MockingboardCard::Get6522IrqDescription(std::string& desc)
//-----------------------------------------------------------------------------
// Notes on Phasor's AY-3-8913 chip-select & r/w: (GH#1192)
// ----------------------------------------------
//
// Where: AY1 is the primary AY-3-8913 connected to 6522, and AY2 is the 2nd-ary.
//
// AFAICT, inputs to the Phasor GAL are:
// . ORB.b4:3 = Chip Select (CS) for AY1 & AY2 (active low)
// . ORB.b2:0 = PSG Function (RESET, INACTIVE, READ, WRITE, LATCH)
// . Phasor mode (Mockingboard, Echo+, Phasor-native)
// . Slot inputs (address, reset, etc)
// And outputs from the GAL are:
// . GAL CS' for AY1 & AY2 (not just passed-through, but dependent on PSG Function)
// (Not PSG Function - probably just passed-through from 6522 to the chip-selected AY-3-8913's)
//
// In Phasor-native mode, GAL logic:
// . AY2 LATCH func selects AY2 and AY1; sets latch addr for AY2 and AY1
// . AY1 LATCH func selects AY1; deselects AY2; sets latch addr for AY1
// . AY2 WRITE func writes AY2 if it's selected
// . AY1 WRITE func writes AY1; writes AY2 if it's selected
//
// EG, to do a "AY1 LATCH", then write 6522 ORB with b4:3=%01, b2:0=%111
//
void MockingboardCard::WriteToORB(BYTE subunit)
{
BYTE value = m_MBSubUnit[subunit].sy6522.Read(SY6522::rORB);
@ -214,12 +238,7 @@ void MockingboardCard::WriteToORB(BYTE subunit)
AY8910_Write(subunit, AY8913_DEVICE_B, value);
if (nAY_CS == 0)
{
SY6522& r6522 = m_MBSubUnit[subunit].sy6522;
BYTE ora = r6522.GetReg(SY6522::rORA);
ora |= r6522.GetReg(SY6522::rDDRA) ^ 0xff; // for any DDRA bits set as input (logical 0), then set them in ORA
r6522.SetRegORA(ora); // empirically bus floats high (or pull-up?) if no AY chip-selected (so DDRA=0x00 will read 0xFF as input)
}
m_MBSubUnit[subunit].sy6522.UpdatePortAForHiZ();
}
else
{
@ -240,7 +259,7 @@ void MockingboardCard::AY8910_Write(BYTE subunit, BYTE ay, BYTE value)
{
// RESET: Reset AY8910 only
AY8910_reset(subunit, ay);
pMB->Reset();
pMB->Reset(QueryType());
}
else
{
@ -270,7 +289,7 @@ void MockingboardCard::AY8910_Write(BYTE subunit, BYTE ay, BYTE value)
if (pMB->isChipSelected[ay] && pMB->isAYLatchedAddressValid[ay])
r6522.SetRegORA(AYReadReg(subunit, ay, pMB->nAYCurrentRegister[ay]) & (r6522.GetReg(SY6522::rDDRA) ^ 0xff));
else
r6522.SetRegORA(r6522.GetReg(SY6522::rDDRA) ^ 0xff);
r6522.UpdatePortAForHiZ();
break;
case AY_WRITE: // 6: WRITE TO PSG
@ -510,7 +529,7 @@ void MockingboardCard::Reset(const bool powerCycle) // CTRL+RESET or power-cycle
for (BYTE ay = 0; ay < NUM_AY8913_PER_SUBUNIT; ay++)
AY8910_reset(subunit, ay);
m_MBSubUnit[subunit].Reset();
m_MBSubUnit[subunit].Reset(QueryType());
m_MBSubUnit[subunit].ssi263.SetCardMode(PH_Mockingboard); // Revert to PH_Mockingboard mode
m_MBSubUnit[subunit].ssi263.Reset();
}
@ -764,6 +783,12 @@ BYTE MockingboardCard::PhasorIOInternal(WORD PC, WORD nAddr, BYTE bWrite, BYTE n
else if (m_phasorMode == PH_Phasor)
m_phasorClockScaleFactor = 2;
if (m_phasorMode == PH_Mockingboard)
{
for (BYTE subunit = 0; subunit < NUM_SUBUNITS_PER_MB; subunit++)
m_MBSubUnit[subunit].isChipSelected[0] = true;
}
AY8910_InitClock((int)(Get6502BaseClock() * m_phasorClockScaleFactor));
for (UINT i = 0; i < NUM_SSI263; i++)

6
source/Mockingboard.h
View File

@ -72,14 +72,16 @@ private:
{
nAY8910Number = 0;
// sy6522 & ssi263 have already been default constructed
// Reset() called from MockingboardCard ctor
}
void Reset(void)
void Reset(SS_CARDTYPE type)
{
nAYCurrentRegister[0] = nAYCurrentRegister[1] = 0; // not valid
state[0] = state[1] = AY_INACTIVE;
isAYLatchedAddressValid[0] = isAYLatchedAddressValid[1] = false; // after AY reset
isChipSelected[0] = isChipSelected[1] = false;
isChipSelected[0] = type == CT_MockingboardC ? true : false;
isChipSelected[1] = false;
}
};