public PPI8255(X8086 cpu, InterruptRequest irq)
{
task = new TaskSC(this);
for (int i = 0x60; i <= 0x6F; i++)
{
ValidPortAddress.Add((uint)i);
}
//PPISystemControl = x8086.WordToBitsArray(&HA5, PPISystemControl.Length)
//PPI = x8086.WordToBitsArray(&HA, PPISystemControl.Length)
//PPICommandModeRegister = &H99
this.cpu = cpu;
this.sched = cpu.Sched;
this.irq = irq;
if (cpu.PIT != null)
{
timer = cpu.PIT;
timer.SetCh2Gate((ppiB & 1) != 0);
}
keyBuf = "";
keyShiftPending = false;
keyMap = new KeyMap();
}
public override void Out(uint port, ushort value)
{
if ((port & 3) == ((uint)1))
{
// Write to port 0x61 (system control port)
// bit 0: gate signal for timer channel 2
// bit 1: speaker control: 0=disconnect, 1=connect to timer 2
// bit 3: read low(0) or high(1) nibble of S2 switches
// bit 4: NMI RAM parity check disable
// bit 5: NMI I/O check disable
// bit 6: enable(1) or disable(0) keyboard clock ?
// bit 7: pulse 1 to reset keyboard and IRQ1
uint oldv = ppiB;
ppiB = (uint)(value);
if ((timer != null) && ((oldv ^ value) & 1) != 0)
{
timer.SetCh2Gate((ppiB & 1) != 0);
#if Win32
if (timer.Speaker != null)
{
timer.Speaker.Enabled = (value & 1) == 1;
}
#endif
}
}
}