To OPRRMS, which part of my statement regarding computers is not true ??? Consider the following: Desktop controls, microprocessors, electronic fuel injection & prime mover emissions controls, even the horn operation,( push a button for a pre - programmed 'long - long - short - long ' sequence), oh yea, blow the horn and the ditch lights alternate flashing. You think all this is done with tubes & servos ??? How about GenSet locomotives ??? The onboard computer determines when to turn on the charging engines, and how many. I have recently read of a new train brake module, computer controlled, that will simplify the mess of hoses & valves under the cab floor, and allow for extended ops betweens required inspections. Let's not forget Distributed Power Unit controls, GPS tracking, and coming soon : Positive Train Controls.
One last thing, if modern locomotives are NOT computer controlled, why did YOU mention that " The ( Amtrak ) P - 42's are notorious for their computer problems" ???