Like the Multiplexer DeMultiplexer boxes on the space shuttle.
The collect multiple data sources (and probably provide any driving signals for things like strain gauges) and format the data.
However the MDM's didn't run programs (although I think the later model running on the ISS do)
As embedded flight avionics that suggests they should be under the full DO178b style development process. Nothing less.
Incidentally the first time I heard one of these timer overflow bugs was related to Patriot missile batteries in the 1990 Gulf War for extended periods of time (I heard about it much later)
So it's not exactly an unknown failure mode.
Biting the hand that feeds IT
