[javagram]

FWIW, the Xbox 360 chip was based on the processor developed for the PS3. No mention of F-35 here. “These cores are slightly modified versions of the PPE in the Cell processor used on the PlayStation 3” https://en.m.wikipedia.org/wiki/Xenon_(processor)

[torginus]

Still, nothing would've prevented IBM from using the Cell PPE as the basis for a PowerPC chip for the military, so that doesn't disprove the theory.

[monocasa]

I know that the Xenon was being simultaneously taped out with the Cell PPE, so it doesn't derive from another cell derived core.

The book "The Race for a New Game Machine" goes over the timing pretty well.