Standards Western Automatic Computer | 1950
SWAC (Standards Western Automatic Computer) is an early electronic digital computer that was created in 1950 by the National Bureau of Standards (NBS) in Los Angeles, California. It was designed by Harry Husky.
Like SEAC, SWAC was a small temporary computer built around the same time, designed to be operational quickly while NBS awaited the completion of more powerful computers (such as RAYDAC).
This machine used 2,300 vacuum tubes and had a memory consisting of 256 words, with each word being 37 bits thanks to the use of Williams tubes. The basic operations were limited to seven, including addition, subtraction, and fixed-point multiplication, and it also supported comparison, data extraction, input, and output. A drum memory was added a few years later.
When SWAC was completed in August 1950, it was the fastest computer in the world, maintaining this status until the IAS computer was completed a year later. Adding two numbers and storing the result took 64 microseconds, while multiplication took 384 microseconds. It was used by the NBS until the closure of its Los Angeles office in 1954, and was then modified and used at UCLA until 1967, where it was rented out for $40 per hour.
In January 1952, Raphael M. Robinson used SWAC to discover five of the largest known Mersenne primes with 157, 183, 386, 664, and 687 digits. Additionally, SWAC was crucial for Dorothy Hodgkin's X-ray analysis of the structure of vitamin B12, which formed the basis for her winning the Nobel Prize in Chemistry in 1964.

