THE WHIRLWIND PROJECT

by R. J. Reiman, Historian

In the late 1940's and 1950's, most computers were sponsored by defense establishments for such tasks as ballistic trajectories {ENIAC], H-Bomb scientific calculations [EDVAC], guided missiles [BINAC]. When computer technology matched commercial application, such as air traffic control, that technology then entered into the marketplace.

Whirlwind computer project was by MIT, and was sponsored by the Navy. The Navy sought a general purpose flight trainer and stability analyzer for aerodynamic design and needed to be programmable so that it could be suited to every type of aircraft. MIT Servomechanism Laboratory assigned 26 year old Jay W. Forrester, a graduate of the University of Nebraska, to build the controller for the trainer-analyzer. It had to be real-time, mimic the behavior of a wide range aircraft, react to pilot's moves, maneuver the cock pit, drive the instrument panel, simulate wind resistance, and record the "flight" for later analysis.

An analogue computer was tried, but proved to be too inaccurate and inflexible. In 1945, Jerry Crawford of MIT suggested a digital computer be used, based on the success of ENIAC. Limited availability of test equipment, components, and instruments added to the difficulty. By 1947, Forrester-Everett team had designed a high-speed electronic stored-program computer for real-time service. It could also do aircraft control, or run a factory! In 1948, Whirlwind was focused on the real-time computer only, employed 175 people including 70 engineers and technicians. In the team, Forrester was the thinker and idea man. and Everett managed people and could go to the heart of the problem. Whirlwind took 3 years to build, was 2 and a half times the size of ENIAC, with 4,000 tubes to ENIAC's 18,000.

Its internal read/write memory consisted of 32 CRT'S , storing 2,048 96 bit words. These lasted only a month with charges of electrons stored on the face of the tubes, and these tended to fade and result in a loss of memory. Forrester experimented with material developed in Germany during World War II for magnetic amplifiers {Deltamax}. He formed this material into spiral rings, and magnetized first in one direction. and then in the opposite direction, but the material was too slow and was sensitive to physical pressures. The team then strung up doughnut-like rings or cores of magnetic material on a grid of wires, establishing coordinates, so it could serve as an address. By energizing the proper pair of row and column wires on a given grid, the computer could read or write a bit into a magnetic core memory. Ceramic ferrite proved to be much faster and hardier than Deltamax. A special smaller version of Whirlwind was built under the direction of Kenneth Olsen, who later established Digital Equipment Corporation. The test computer worked!

In 1953, core memory made Whirlwind performance impressive, operating speed doubled, and maintenance time fell to 2 hours per week. The core memory design would go on to become a standard product of all computers of its time. Whirlwind became a central element in the Air Defense System which was established to counter the Soviet threat of long-range bombers with atomic bombs.