public int OnIORead(int location)
{
int function = 0;
IOHardware hardware = DecodeIOPort(location, ref function);
switch (hardware)
{
case IOHardware.PPI8255:
{
return(m_ppi.IORead(function));
}
case IOHardware.CRTC:
{
return(m_crtc.OnIORead(function));
}
}
return(0xff);
}