>>64383435
>The US's ATACMS uses microchips from the 70s.
Well, a ballistic trajectory is the equivalent to a "straight line", you don't need a lot of computing power if you simplify your missile with a nice and aerodynamic shape, a few corrections per second in the worst case is enough.
But that is for the INS ATACMS, anything with GPS will require a anti-spoofing and high accuracy receiver that needs a 'beefy' DSP capable of million operations per second. But the GPS receiver is just a module and people tends to ignore the processing power of "modules", the F-22 or F-15 are another example, the main computer isn't faster than a Pentium IV but 99.9% of the processing power is done by modules only sending the result (like a very accurate location of a target and type of target) and for a current fighters is in the order of 100 thousand million math operations per second to one trillion.
>TLDR: you don't need a lot of processing power for some tasks but anything related to sensors/radio/radars will require absurd amounts of processing power.