The Whirlwind computer was developed at the Massachusetts Institute of Technology. It is the first computer that operated in real time, used video displays for output, and the first that was not simply an electronic replacement of older mechanical systems. Its development led directly to the US Air Force's SAGE system, and indirectly to almost all business computers in the 1960s. A computer is a device or machine for processing information from data according to a program — a compiled list of instruction. ... The Massachusetts Institute of Technology, or MIT, is a research and educational institution located in the city of Cambridge, Massachusetts, USA. MIT is a widely renowned leader in science and technology, as well as in many other fields, including engineering systems, management, economics, linguistics, political science, and philosophy. ... It has been suggested that Real-time computing be merged into this article or section. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... Seal of the Air Force. ... SAGE Sector Control Room. ... The 1960s in its most obvious sense refers to the decade between 1960 and 1969, but the expression has taken on a wider meaning over the past twenty years. ...

Techno-historical background

During World War II the US Navy approached MIT about the possibility of creating a computer to drive a flight simulator for training bomber crews. They envisioned a fairly simple system in which the computer would continually update a simulated instrument panel based on control inputs from the pilots. Unlike older systems like the Link Trainer, the system they envisioned would have a considerably more realistic aerodynamics model that could be adapted to any type of plane. World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrinations, and the use of new, extremely devastating weapons like the atom bomb World War II, also known as the Second World War, was a mid-20th-century conflict that engulfed much of the globe... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... Interior Cockpit of a modern Flight Simulator A flight simulator is a system that tries to replicate, or simulate, the experience of flying an airplane as closely and realistically as possible. ... A bomber is a military aircraft designed to attack ground targets, primarily by dropping bombs. ... The Link Trainer, or pilot maker was created in the mid-1930s out of the need for a safe way to teach new pilots how to fly IFR. It was created by Edwin Albert Link, who was formerly an Organ builder, used is knowledge of pumps valves and bellows to... Aerodynamics is a branch of fluid dynamics concerned with the study of gas flows, first analysed by George Cayley in the 1800s. ...

A short study by the MIT Servomechanisms Laboratory concluded that such a system was certainly possible. The Navy decided to fund development under Project Whirlwind, and the lab placed Jay Forrester in charge of the project. They soon built a large analog computer for the task, but found that it was inaccurate and inflexible. Solving these problems would require a much larger system, perhaps one so large as to be impossible to construct. Jay Wright Forrester (born 14 July 1918 Climax, Nebraska) is an American pioneer of computer engineering. ... An analog/analogue computer is a form of computer that uses electronic or mechanical phenomena to model the problem being solved by using one kind of physical quantity to represent another. ...

In 1945 Jerry Crawford, another member of the MIT team, saw a demonstration of ENIAC and suggested that a digital computer was the solution. Such a machine would allow the accuracy of the simulation to be improved with the addition of more code in the computer program, as opposed to adding parts to the machine. As long as the machine was fast enough, there was no theoretical limit to the complexity of the simulation. 1945 was a common year starting on Monday (link will take you to calendar). ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer, was long thought to have been the first electronic computer designed to be Turing-complete, capable of being reprogrammed by rewiring to solve a full range of computing problems. ... // A computer program or software program (usually abbreviated to a program) is a step-by-step list of instructions written for a particular computer architecture in a particular computer programming language. ...

Up until this point all computers constructed were dedicated to single tasks, run in batch mode. A series of inputs were set up in advance and fed into the computer, which would work out the answers and print them. This was not appropriate for the Whirlwind system, which needed to operate continually on an ever-changing series of inputs. Speed became a major issue, whereas with other systems it simply meant waiting longer for the printout, with Whirlwind it meant seriously limiting the amount of complexity the simulation could include. Batch processing is the sequential execution of a series of programs (jobs) on a computer. ...

Technical description

Design and construction

By 1947, Forrester and Everett completed the design of a high-speed stored-program computer for this task. Most computers of the era operated in bit-serial mode, using single-bit arithmetic and feeding in large words, often 48 or 60 bits in size, one bit at a time. This was simply not fast enough for their purposes, so Whirlwind included sixteen such math units, operating on a complete 16-bit word every cycle in bit-parallel mode. Ignoring memory speed, Whirlwind was essentially sixteen times as fast as other machines. Today almost all machines work in this fashion, albeit with larger 32- or 64-bit words. 1947 was a common year starting on Wednesday (link will take you to calendar). ...

The word size was selected after some deliberation. The machine worked by passing in a single address with almost every instruction, thereby reducing the amount of memory accesses. For operations with two operands, adding for instance, the "other" operand was assumed to be the last one loaded. Whirlwind operated much like a reverse Polish notation calculator in this respect; except there was no operand stack, only an accumulator. The designers felt that 2000 words of memory would be the minimum usable amount, requiring 11 bits to represent an address, and that 16 to 32 instructions would be the minimum for another 5 bits -- and so it was 16-bits. Nevertheless the small word size led John von Neumann to conclude the machine would be worthless. Reverse Polish notation (RPN) , also known as postfix notation, is an arithmetic formula notation, derived from the Polish notation introduced in 1920 by the Polish mathematician Jan Łukasiewicz. ... A modern basic arithmetic calculator A calculator is a device for performing numerical calculations. ... John von Neumann in the 1940s. ...

Construction of the machine started the next year, an effort that employed 175 people including 70 engineers and technicians. Whirlwind took 3 years to build and first went online on April 20, 1951. The project's budget was $1 million a year, and after three years the Navy had already lost interest. However it was around this time that the USSR detonated their first atomic bomb, and the USAF picked up the work under Project Claude. 1951 (MCMLI) was a common year starting on Monday; see its calendar. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ...

The core of the machine

Speed of the original design (20 KIPS) turned out to be too slow to be very useful, and most of the problem was attributed to the fairly slow speed of the Williams tubes (or, more accurately, Williams-Kilburn tubes) used for main memory of 256 words. Forrester started looking at replacements, first using magnetic tape formed into spirals, and eventually creating core memory. Speed was roughly doubled (40 KIPS) as a result of using core when the new version was completed in 1953. The addition time was 49 microseconds and the multiplication time was 61 microseconds (before the main memory was converted to magnetic core). The Williams tube or (more accurately) the Williams-Kilburn tube (after Freddie Williams and coworker Tom Kilburn), developed about 1946 or 1947, was a cathode ray tube used to store electronic data. ... Primary storage is a category of computer storage, often called main memory. ... In computing, word is a term for the natural unit of data used by a particular computer design. ... A 16×16 cm area core memory plane of 128×128 bits, i. ... 1953 is a common year starting on Thursday. ... A microsecond is an SI unit of time equal to one millionth (10-6) of a second. ...

After the magnetic core memory was installed, the Whirlwind became the fastest computer of its time. With the change it had an addition time of 8 microseconds, a multiplication time of 25.5 microseconds, and a division time of 57 microseconds (excluding memory access time). The access time had been 8,500 microseconds for drum memory which was reduced to only 8 microseconds with the magnetic core.

The new core-based machine was fast enough for use in SAGE, and an industrial effort was started in order to mass-produce the AN/FSQ-7 computers for this role. RCA was a front-runner, but IBM was eventually selected instead. They started production in 1957, along with a massive construction project to build the buildings, power and communications network needed to feed the SAGE systems with data. SAGE Sector Control Room. ... The AN/FSQ-7 (aka Whirlwind II) intercept computer, developed by Cambridge Research Laboratory and IBM in partnership with the US Air Force, was, as its alias suggests, a modified Whirlwind computer. ... RCA, formerly an initialism for the Radio Corporation of America, is now a trademark used by two companies for products descended from that common ancestor: Thomson SA, which manufactures consumer electronics like RCA-branded televisions, DVD players, video cassette recorders, direct broadcast satellite decoders, camcorders, audio equipment, telephones, and related... International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ...

What came of the Whirlwind?

Whirlwind II ran in a support role for SAGE until June 30, 1959. A member of the project team, Bill Wolf, then rented the machine for a dollar a year until the late 1970's. At that point it was taken over by Ken Olsen, who kept it for a while before transferring it to the Smithsonian. Ken H. Olsen (born on February 20, 1926) was an American engineer who founded Digital Equipment Corporation in 1957. ... The Smithsonian castle, as seen through the garden gate. ...

The Whirlwind used approximately 5000 vacuum tubes. An effort was also started to convert the Whirlwind design to a transistorized form, led by Kenneth Olsen and known as the TX-0. TX-0 was very successful and plans were made to make an even larger version known as TX-1. However this project was far too ambitious and had to be scaled back to a smaller version known as TX-2. Even this version proved troublesome, and Olsen left in mid-project to start DEC. DEC's PDP-1 was essentially a collection of TX-0 and TX-2 concepts in a smaller package. In electronics, a vacuum tube (American English) or (thermionic) valve (British English) is a device generally used to amplify a signal. ... Ken H. Olsen (born on February 20, 1926) was an American engineer who founded Digital Equipment Corporation in 1957. ... The TX-0, for Transistorized Experimental computer zero but affectionately referred to as the tixo, was the first fully transistorized computer to enter service and contained a then-huge 64K of 18-bit words of core memory. ... The MIT Lincoln Laboratory TX-2 computer was the successor to the Lincoln TX-0 and was known for its role in advancing both artificial intelligence and human-computer interaction. ... Digital Equipment Corporation was a pioneering company in the American computer industry. ... The PDP-1 (Programmed Data Processor-1) was the first computer in Digital Equipments PDP series and was first produced in 1960. ...

References

• John F. Jacobs, The SAGE Air Defense System: A Personal History (MITRE Corporation, 1986) also contains much material on the Whirlwind

External links

• Computer Structures: Readings & Examples — The Whirlwind I computer
• Whirlwind documentation