public int performRead(int address, long cycles) {
    System.out.println("TFE_CS8900: read " + Integer.toString(address, 16));
    switch (address) {
    case PPDATA:
      break;
    case PPDATA + 1:
      break;
    case PACKET_PP:
      break;
    case PACKET_PP + 1:
      break;
    case TXCMD:
      break;
    case TXLEN:
      break;
    case RXTXREG:
      break;
    case RXTXREG + 1:
      break;
    }
    return 0;
  }