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It's a physical device at the bleeding edge of capabilities. Defects are pretty much a guarantee, and getting a working sample is a numbers game. Is it really that strange to not get a 100% yield?

Having 5 working devices out of 21 is normal. The problem is that the other 16 weren't mentioned.

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Well you also need to account for what kind of deviation are we talking about between the 21. If they selected the 5 because they were the best, but the others showed results that were within say 0-5% of the 5, then sure that is acceptable. But if we’re talking about flipping a coin 21 times, seeing heads 16 times and then choosing the 5 tails outcomes as the results, then I would say that’s pretty unacceptable.

Like I said, a single misplaced atom is enough to wreak havoc in the behaviour of these things. That's not the problem, everyone knows there's a large gap between phenomena observed, and making it consistently manufacturable with high yield.

I do not think this is the right metaphor. Having 5 devices work out of 21 is actually a better yield than what TSMC would get with a brand new process. This is not just normal, this is expected. It is all the other allegations that make this be a very questionable case.

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