/// <summary>
/// Returns the current value of a sequencer register.
/// </summary>
/// <param name="address">Address of register to read.</param>
/// <returns>Current value of the register.</returns>
public byte ReadRegister(SequencerRegister address)
{
return(address switch
{
SequencerRegister.Reset => this.Reset,
SequencerRegister.ClockingMode => this.ClockingMode,
SequencerRegister.MapMask => this.MapMask,
SequencerRegister.CharacterMapSelect => this.CharacterMapSelect,
SequencerRegister.SequencerMemoryMode => (byte)this.SequencerMemoryMode,
_ => 0
});
public void WriteByte(int port, byte value)
{
switch (port)
{
case Ports.DacAddressReadMode:
Dac.ReadIndex = value;
break;
case Ports.DacAddressWriteMode:
Dac.WriteIndex = value;
break;
case Ports.DacData:
Dac.Write(value);
break;
case Ports.GraphicsControllerAddress:
graphicsRegister = (GraphicsRegister)value;
break;
case Ports.GraphicsControllerData:
Graphics.WriteRegister(graphicsRegister, value);
break;
case Ports.SequencerAddress:
sequencerRegister = (SequencerRegister)value;
break;
case Ports.SequencerData:
var previousMode = Sequencer.SequencerMemoryMode;
Sequencer.WriteRegister(sequencerRegister, value);
if ((previousMode & SequencerMemoryMode.Chain4) == SequencerMemoryMode.Chain4 && (Sequencer.SequencerMemoryMode & SequencerMemoryMode.Chain4) == 0)
{
EnterModeX();
}
break;
case Ports.AttributeAddress:
if (!attributeDataMode)
{
attributeRegister = (AttributeControllerRegister)(value & 0x1F);
}
else
{
AttributeController.WriteRegister(attributeRegister, value);
}
attributeDataMode = !attributeDataMode;
break;
case Ports.AttributeData:
AttributeController.WriteRegister(attributeRegister, value);
break;
case Ports.CrtControllerAddress:
case Ports.CrtControllerAddressAlt:
crtRegister = (CrtControllerRegister)value;
break;
case Ports.CrtControllerData:
case Ports.CrtControllerDataAlt:
int previousVerticalEnd = CrtController.VerticalDisplayEnd;
CrtController.WriteRegister(crtRegister, value);
if (previousVerticalEnd != CrtController.VerticalDisplayEnd)
{
ChangeVerticalEnd();
}
break;
}
}
