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Tidy the MC6850 a little, mainly to show that the step method is only called via the clock tick.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-05-27 10:53:44 +01:00
parent a78e6cb23c
commit 133fc83e89
2 changed files with 60 additions and 72 deletions
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1
MC6809/MC6809.Test/Board.cs
View File

@ -139,7 +139,6 @@ namespace EightBit
if (this.ACIA.Selected)
{
this.ACIA.RW.Lower();
this.ACIA.DATA = this.Data;
this.AccessAcia();
}
}

131
MC6850/MC6850.cs
View File

@ -321,8 +321,6 @@ namespace EightBit
private bool TransmitReadyHigh => this.transmitControl == TransmitterControl.ReadyHighInterruptDisabled;
//// private bool TransmitReadyLow => !this.TransmitReadyHigh;
private byte Status
{
get
@ -345,70 +343,6 @@ namespace EightBit
this.startup = StartupCondition.ColdStart;
}
public void Step()
{
this.ResetCycles();
if (!this.Activated)
{
return;
}
this.OnAccessing();
var writing = this.RW.Lowered();
var reading = !writing;
var registers = this.RS.Lowered();
var transferring = !registers;
if (registers)
{
if (writing)
{
this.counterDivide = (CounterDivideSelect)(this.DATA & (byte)(ControlRegister.CR0 | ControlRegister.CR1));
if (this.counterDivide == CounterDivideSelect.MasterReset)
{
this.Reset();
}
else
{
this.wordSelect = (WordSelect)((this.DATA & (byte)(ControlRegister.CR2 | ControlRegister.CR3 | ControlRegister.CR4)) >> 2);
this.transmitControl = (TransmitterControl)((this.DATA & (byte)(ControlRegister.CR5 | ControlRegister.CR6)) >> 5);
this.receiveControl = (ReceiveControl)((this.DATA & (byte)ControlRegister.CR7) >> 7);
this.RTS.Match(this.TransmitReadyHigh);
}
}
else
{
this.DATA = this.Status;
}
}
else
{
this.IRQ.Raise();
if (writing)
{
this.StartTransmit();
}
else
{
this.CompleteReceive();
}
}
// Catch the transition to lost carrier
if (this.oldDcdLine.Lowered() && this.DCD.Raised())
{
this.IRQ.Raise();
this.statusRead = false;
}
this.oldDcdLine = this.dcdLine;
this.OnAccessed();
}
public void MarkTransmitComplete()
{
this.statusTDRE = this.CTS.Lowered();
@ -455,15 +389,70 @@ namespace EightBit
this.Step();
}
////private static byte SetFlag(byte f, StatusRegisters flag) => SetFlag(f, (byte)flag);
////private static byte SetFlag(byte f, StatusRegisters flag, int condition) => SetFlag(f, (byte)flag, condition);
private static byte SetFlag(byte f, StatusRegister flag, bool condition) => SetFlag(f, (byte)flag, condition);
private static byte ClearFlag(byte f, StatusRegister flag) => ClearFlag(f, (byte)flag);
////private static byte ClearFlag(byte f, StatusRegisters flag, int condition) => ClearFlag(f, (byte)flag, condition);
private void Step()
{
this.ResetCycles();
if (!this.Activated)
{
return;
}
this.OnAccessing();
var writing = this.RW.Lowered();
var registers = this.RS.Lowered();
if (registers)
{
if (writing)
{
this.counterDivide = (CounterDivideSelect)(this.DATA & (byte)(ControlRegister.CR0 | ControlRegister.CR1));
if (this.counterDivide == CounterDivideSelect.MasterReset)
{
this.Reset();
}
else
{
this.wordSelect = (WordSelect)((this.DATA & (byte)(ControlRegister.CR2 | ControlRegister.CR3 | ControlRegister.CR4)) >> 2);
this.transmitControl = (TransmitterControl)((this.DATA & (byte)(ControlRegister.CR5 | ControlRegister.CR6)) >> 5);
this.receiveControl = (ReceiveControl)((this.DATA & (byte)ControlRegister.CR7) >> 7);
this.RTS.Match(this.TransmitReadyHigh);
}
}
else
{
this.DATA = this.Status;
}
}
else
{
this.IRQ.Raise();
if (writing)
{
this.StartTransmit();
}
else
{
this.CompleteReceive();
}
}
// Catch the transition to lost carrier
if (this.oldDcdLine.Lowered() && this.DCD.Raised())
{
this.IRQ.Raise();
this.statusRead = false;
}
this.oldDcdLine = this.dcdLine;
this.OnAccessed();
}
private void OnAccessing() => this.Accessing?.Invoke(this, EventArgs.Empty);