I don't think you can say the lethal bugs were all in the frontend code. First, machines of that age didn't have as clear of a distinction between front and bac

I don't think you can say the lethal bugs were all in the frontend code. First, machines of that age didn't have as clear of a distinction between front and backend. Second, any good back end has bulletproof safeguards against bad frontend input. It makes more design sense to safeguard the backend against spamming input than the frontend, because the frontend is more likely to require redesign, and multiple frontends can interact with the same backend. More than anything else, this accident shows the importance of fuzz testing your critical logic, the importance of hardware interlocks, and the importance of multiple independent layers of interlocks.