public void poke(UInt16 address, byte value)
{
switch (address)
{
case 0:
// when switching an unused bit from output (where it contained a
// stable value) to input mode (where the input is floating), some
// of the charge is transferred to the floating input
if (dir != value)
{
// check if bit 6 has flipped from 1 to 0
if ((dir & 0x40) != 0 && (value & 0x40) == 0)
{
dataBit6.writeBit(pla.getPhi2Time(), data);
}
// check if bit 7 has flipped from 1 to 0
if ((dir & 0x80) != 0 && (value & 0x80) == 0)
{
dataBit7.writeBit(pla.getPhi2Time(), data);
}
dir = value;
updateCpuPort();
}
value = pla.getLastReadByte();
break;
case 1:
// when writing to an unused bit that is output, charge the "capacitor",
// otherwise don't touch it
if ((dir & 0x40) != 0)
{
dataBit6.writeBit(pla.getPhi2Time(), value);
}
if ((dir & 0x80) != 0)
{
dataBit7.writeBit(pla.getPhi2Time(), value);
}
if (data != value)
{
data = value;
updateCpuPort();
}
value = pla.getLastReadByte();
break;
default:
break;
}
ramBank.poke(address, value);
}
public override void writeMemByte(UInt16 addr, byte value)
{
ramBank.poke(addr, value);
}