TODO:
 - How to check connections between  half-duplex and full duplex ethernet cards.
   Mi a helyzet, ha így konfiguráltuk, mennyire hasonlít a működés a valósághoz?

 - The EtherHub, EtherBus must assert halfduplex communication!!!

 - The EtherBus should require 10Mbit speed

 - How abort a transmit, when detected a collision.