I actually did my homework(!) on this after my previous post. Disclaimers: 1) I'm not a real lawyer, although I did a few law courses in university. 2) I read the Finnish law; I'm sure it is pretty much compliant to EU laws and those should be pretty much like anywhere else. 3) I'm using layman English, I don't know the real legal translations. 4) The conclusions are my own.
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Short version: Turns out the Rigol (or HP) software licensing terms don't matter, unless they specifically allow hacking and you know they do. Hacking your scope is not ok.
Long version:
- When you buy something, you enter to implied agreements. It is not necessary to read or sign anything. You buy a cup of coffee, and there are a lot of
legally binding agreements on both sides, implied by the act. No signed agreements are needed.
- Hacking keys to get something you didn't pay for is illegal (payTV, turning demo software to full version etc).
- Ignorance is not bliss. If it is commonly known or you personally should have known something to be illegal, it is. In other words: A professional or an advanced hobbyist (needing a software based scope) should understand the concept of embedded software. Everyone should understand the concept of paying for key, getting a feature.
- Embedded software is software too, with the same protections.
All those are legal facts, that I think can't be really argued, unless laws are changed. You can argue my summary: Buying a scope (or other device with embedded software), the user enters to licensing agreement with the manufacturer. The terms of the agreements are such that could be reasonably expected. You didn't buy the high bandwidth software option, which was available.
Some analogies that I think are relevant: You buy a set-top box, but you are not free to do what you want with it. Specifically, you can't unlock channels that you did not pay for. You expect that keygen program turns your scope to a real higher end model, whereas overclocking a CPU, the expectation is that the manufacturer guarantees the operation to a limit your paid for and you are experimenting about how high you can go. Totally different issues.