A semi in British slang is a partially erect penis. I guess “atomic semi” would sound like “partially erect micro-penis” to a Brit.

I couldn't decide between micro-penis, and some kind of comic-book hulk type appendage. But your description was very eloquent, so I'll go with that.

Not American, not a Brit here. Care to explain?

I'm neither either, but Jim Keller is a (the most?) legendary microprocessor engineer, and responsible for so much in the semiconductor industry. Kind of what Messi is for football, but for processors.

no, we don't have that slang.