In uk.transport.london Recliner wrote:
Yes, that is surprising. Presumably the same data feeder system is used,
but the computerised visual and audio subsystems are different, maybe even
from different sub-contractors.

I assume it's like a modern car, which is a distributed system containing
dozens of ECUs (ie computers) flying in loose formation, joined by a
network. In the case of an 8 or 12 coach train there are probably hundreds
of nodes.

Building distributed systems is hard, especially when heterogenous, and when
involving physical inputs which are difficult to simulate in a test
environment (eg the kinematics of the train, doors, toilets, etc).

Theo