The Control Data Corporation (CDC) 3600 computer arrived at NCAR in November 1963, but the operating system was not ready.
SCD staff put together an operating system sufficient to be able to utilize the machine, and by early 1964, SCD was able to provide service on the CDC 3600.
By the end of 1964, usage had grown from 50 to 300 hours per month and SCD had run approximately 19,000 jobs.
The CDC 3600 was a beautiful computer with smoked glass panels and a "solid and stunning" look. Seymour Cray had worked on the circuitry.
The CDC 3600 had 32,700 48-bit words of memory and supported the FORTRAN 66 compiler.
The CDC 3600 was kept for several years after the arrival of the CDC 7600 in 1966.