Question was prompted by a remark by the following source, to the effect that,
"In the course of my research, I had an acquaintance who worked for the NSA as a civilian during the 1960s, and he offhandedly said they were running computers with a clock speed of 650Mhz at that time."
This source will be poo-pooed by many here I think, because we can probably look up Wikipedia for this person and find words like "debunked", "pseudoscience", "crank", or other such terms that when encountered by many people act like the "Jedi mind trick" and foreshorten any further consideration.
Nevertheless, it seems there could be classified breakthroughs in technology that many years later make their way into the public market. I think it's interesting to speculate how far ahead secret tech could be.
Source: Richard Dolan, Aerial Phenomena with Richard Dolan, S2 Ep8, "Is there a breakaway civilization?"
Cray sold lots of machines to the NSA. ("HPC is dominated by a full line of systems from Cray Research" - https://publishing.cdlib.org/ucpressebooks/view?docId=ft0f59... ).
The 1970s era Cray-1 was 80 MHz, and Cray was pushing the limits of CPU technology.
You really think the NSA had the Cray installation, with NSA's own OS (Folklore) and more, and had an internal system which was >10x more powerful, that no one has heard of, with no information leak about that technology to the wider world?
Whackadoodle conspiracy nonsense.
Or rather, what's more likely, that that statement is true, or that Dolan and/or the NSA civilian got something wrong?