Hi!

Complicated one, let's say i have a need to keep certain programs/data
in running order for the next 50 years.

Theoretically speaking, it's doable. What history has shown us so far is
that the reality may be a little different. Semiconductors ("chips") are
themselves very reliable and can last an extremely long time in a well
designed circuit running within specifications or close to. The problematic
areas include mechanical parts (disk storage), power supplies and some
supporting components like capacitors.

That said, I have a lot of 286 and 386 machines around that are still in
fairly regular use.

You also have to factor in exteral influences...lightning strikes, natural
disasters, etc. These things can wipe out otherwise healthy and properly
functioning equipment almost instantly. And don't forget the upkeep (human)
factor as well. If everything else goes well, the systems will still need
periodic restarting, cleaning and other work.

Any suggestions?

Truthfully, I think you'd do very well to consider building a system that
could be upgraded and moved to newer equipment as time goes on and things
wear out. Sure, you could stockpile many parts and systems in order to keep
the same old thing running along, but leaving yourself an option to upgrade
to more modern hardware over time is a much better plan. You can reasonably
assume that new computer hardware will be available. You can't assume that
any spare parts will be in serviceable condition by the time you need them.

William