It’s a 3D circuit module for the Cray-2, the fastest computer in the world in 1985. See the QIP chips, see the vertical connections between boards, see the absurd density which required immersive cooling - a constant flow at one inch per second through every module. And there are over three hundred modules, each with 750 or so chips. And as each module puts out several hundred watts of heat, there’s 200 gallons of Fluorinert. … There’s so much memory in each Cray-2, it’s more than the total amount of memory shipped in all previous Crays combined, and it’s arranged in 128 banks for extreme bandwidth. There are four ‘background’ CPUs doing the heavy lifting, with another in the foreground looking after things. Each background CPU has some local memory too. A few more photos of components here.
Much more on Seymour Cray and his successive computer designs here.
Lots more technical info in the product brochure for Cray-2 in this 1985 brochure.
And, finally, a short video from NASA on “The World’s Most Powerful Computer”:
(recycled from a G+ post, as linked in this compendium of photos of stacked DIP chips.)