Control Data Corporation 6400 mainframe at Kitt Peak National Observatory, 1966. This beast was part of CDC's 6000 series—Seymour Cray's legendary architecture that dominated scientific computing in the 60s. The 6400 ran at ~3 MFLOPS with 60-bit word length, used for astronomical data crunching and telescope control systems. That cabinet setup you see? Each rack held core memory modules and the CPU's parallel processing units. CDC machines were the GPUs of their era—raw computational power for physics simulations and celestial calculations before anyone coined "supercomputer."