[indigochill]

It's interesting to try to fit what is often talked about as "future-proofing" and "reusability" into the development of a general-purpose CPU, since CPUs are in a sense the ultimate reusable system.

In an overly simplified textbook example of designing/building a CPU, you have an ISA you're building the CPU to support. The ISA defines a finite set of operations and their inputs, outputs, and side effects (like storing a value in a particular register). Then you build the CPU to fulfill those criteria.

In my experience, designers that want reusability usually don't have enough precision in how they want to reuse a system so an ISA-like design can't be created.

And practically, it's the rare (I might even say non-existent) day-to-day business problem that needs CPU-like flexibility. Usually a system just needs to support a handful of use cases, like integrating with different payment providers. An interface will suffice.

[sshine]

> Usually a system just needs to support a handful of use cases, like integrating with different payment providers.

Building EV chargers is a good dose of electrical engineering combined with talking to dozens of car models and their own particular quirky interpretations of common protocols, which is like designing websites for a market with dozens of unique browser implementations.

In spite of that, it seems half of the complexity is making sure people pay.