One breakthrough from the 19th century and three originating in 20th-century defense research were recognized in June as IEEE Milestones in Electrical Engineering and Computing.
1891 to 1895: Electrification of the Howard Street Tunnel
The initial main-line railroad electrification in the United States was recognized on 21 June. It was first demonstrated by the Baltimore & Ohio (B&O) railroad at its Howard Street Tunnel, in Baltimore, on 27 June 1895. Commercial operation began four days later.
The tunnel ran 2.3 kilometers under a Baltimore thoroughfare already rife with residential and commercial buildings, where ordinances forbade the use of flues and vents to exhaust the smoke produced by steam locomotives. The problem was manageable for southbound steam engines, which could simply coast downhill, producing little smoke, but trains climbing the long slope in the opposite direction would generate enough smoke to obscure visibility and possibly produce enough toxic gases to cause illness or choking. Still, the tunnel was needed as part of a bypass to avoid a cumbersome ferry transfer across the Patapsco River. So in 1891 the B&O began building the tunnel, gambling that suitable electric power would become available once it was complete.
The B&O won the gamble. A contract for the power went to the newly formed General Electric Co., which provided a 2800-kilowatt generating station (at a time when Thomas Edison’s five New York power stations totaled only 3600 kW) and two 1073.8-kW (1440-horsepower) locomotives, 10 times as powerful as any previous unit put into operation.
Northbound trains would stop just south of the tunnel, shut off steam and close their dampers. An electric locomotive would then couple to the train and pull it—with the silent steam locomotive—through the tunnel.
The tunnel, the longest in the B&O system and the longest soft-earth tunnel in the United States, is now operated by CSX Transportation and carries as many as 40 freight trains in a day, many a mile long. It is still such an important part of the U.S. infrastructure that its closing for several days in 2001 (because of chemical fires from a derailed train) disrupted East Coast rail traffic.
After 1910, the growth of the electric power industry enabled the B&O to buy power from local utilities; the original powerhouse site is now occupied by the Camden Yards baseball stadium, home of the Baltimore Orioles. Eventually, the railroad switched to diesel operation.
The Milestone plaque, which was erected at the B&O Railroad Museum near the tunnel, reads:
On 27 June 1895, at the nearby Howard Street Tunnel, the B&O demonstrated the first electrified main line railroad, and commercial operation began four days later. The electrification involved designing, engineering, and constructing electric locomotives far more powerful than any then existing and creating innovative electric power generation and distribution facilities. This pioneering achievement became a prototype for later main line railroad electrification.
1940 to 1946: LORAN
In October 1940, 13 months after the outbreak of World War II in Europe and 14 months before the United States entered the war, the newly formed National Defense Research Committee (NDRC) contracted with MIT to create a radio navigation system. It became one of the first three projects of MIT’s new Radiation Laboratory, commonly called the Rad Lab. The lab, which also contributed to the development of radar and the atomic bomb, became the NDRC’s largest single activity.
The LORAN (for Long Range Navigation) Division established for the project was headed by Donald G. Fink, a Fellow of IEEE’s predecessor societies, the IRE and AIEE, and later, the executive director of IEEE.
Operating in the low frequency (LF) portion of the radio spectrum, LORAN was the only non-microwave project of the Rad Lab. LORAN was a “hyperbolic navigation” system based on the difference in timing between synchronized, pulse-modulated signals received from paired radio transmitters. By measuring that difference, a navigator could determine the distance to those stations. Lacking absolute distance information, the operator knew only that the position was somewhere on a series of hyperbolic curves. Adding measurements for a second pair of stations produced a grid from which a pair of possible positions could be determined, after which other navigational techniques could resolve the ambiguity.
LORAN was based on a suggestion by IRE Fellow Alfred Lee Loomis, a wealthy inventor and physicist who helped establish the lab and arranged for its initial funding until the federal government provided money. His suggestion was a way of overcoming the range and accuracy limits of the aircraft guidance system used by Britain’s Bomber Command, codenamed GEE for “grid.” The chief researcher and scientist on the project was John Alvin “Jack“ Pierce of Harvard University. Pierce received the 1990 IEEE Medal for Engineering Excellence for his work on LORAN and other navigational systems.
The system was rapidly developed and deployed, despite the difficulties of building stations in remote areas under wartime conditions and the need for cooperation among the countries where stations were sited. The first two LORAN stations, on the U.S. Atlantic coast, were on the air by mid-1942, followed by a station in Canada. By late 1943, stations had been added in Greenland, Iceland, the Faroe Islands (between Norway and Iceland), and the Hebrides (off the west coast of Scotland). By the end of World War II, 25 stations covered the Pacific. All told, by war’s end, 70 stations were in operation, providing nighttime navigation service over 60 million square miles—about 30 percent of the earth’s surface. By 1946, 75 000 maritime and aircraft receivers had been delivered.
LORAN was crucial to the war effort, enabling navy ships and supply convoys to navigate treacherous waters, bombers to find targets, and aircraft to find their way to refueling airfields on small islands dotted across the vast Pacific, all without breaking radio silence.
LORAN also proved useful in peacetime, becoming the chief navigation system for air and maritime transport around the world until superseded by satellite-based GPS. Even today, an enhanced version, eLORAN, is being considered as a backup to GPS and other satellite navigation systems.
The plaque, installed on 27 June, adjacent to the Building 20/Radiation Laboratory memorial in the Gates Lobby of MIT’s Ray and Maria Stata Center on Vassar Street, in Cambridge, Mass., reads:
The rapid development of LORAN—long range navigation—under wartime conditions at MIT’s Radiation Lab was not only a significant engineering feat but also transformed navigation, providing the world’s first near-real-time positioning information. Beginning in June 1942, the United States Coast Guard helped develop, install, and operate LORAN until 2010.
1944 to 1959: The Whirlwind Computer
While the Rad Lab was developing LORAN, other MIT researchers began work on a new computer featuring several significant innovations. Called Whirlwind, it became the first computer to use a video screen for output and magnetic-core random-access memory, and to operate in real time.
Real-time processing—the ability to update what was input after processing had begun—was necessary for the task that spurred the Whirlwind project: control of an interactive flight trainer that would simulate flight for any type of aircraft. The first design, an analog computer, proved inadequate, so in 1945 the MIT team turned to developing a high-speed digital computer.
The flight trainer’s development began under the direction of IRE Fellow Jay W. Forrester of MIT’s Servomechanisms Laboratory. After the project’s emphasis shifted to include high-speed computing, the Whirlwind researchers formed a new Digital Computer Laboratory, still under Forrester’s direction, to continue the project.
Whirlwind could store 2048 16-bit words in memory, processing all 16 bits at once instead of one at a time. Initially, its memory consisted of electrostatic storage tubes, similar to cathode-ray tubes, which offered random data access but required that data be rewritten frequently to prevent loss. Data was not retained when the system was powered down.
With that memory, Whirlwind could process only 20 000 instructions per second (20 KIPS), insufficient for its intended use. Magnetic-core memory, for which Forrester received a patent, doubled the speed to 40 KIPS, retained data even without power, and proved far more reliable than tubes. Commonly referred to simply as core memory, it remained the dominant memory technology until supplanted by semiconductor memory in the 1970s. It also was key to the widespread adoption of computers for industrial and other applications where reliability was required.
The system exploits the ability of ferrite cores to be magnetized in either the clockwise or counterclockwise direction—which can be defined as representing either 1 or 0. The cores are arrayed in a planar matrix with x- and y-axis lines defining each core’s address. Only one bit in each plane can be accessed in each read or write cycle, so the bits of a machine are distributed through a stack of planes, enabling all the word’s bits to be written or read at once. That random-access address scheme, and the computer’s architecture, enabled procedures and programs to be operated interactively.
Whirlwind was built and operated in MIT’s Barta Building, now Building N42, at 211 Massachusetts Avenue, in Cambridge. The computer operated and remained at that location for its lifetime—no surprise, as it was two stories high and weighed several tons. The Milestone plaque, placed on the building on 27 June 2012, where it can be seen by passing pedestrians, reads:
Whirlwind Computer, 1944–1959
The Whirlwind computer was developed at 211 Massachusetts Avenue by the Massachusetts Institute of Technology. It was the first real-time high-speed digital computer using random-access magnetic-core memory. Whirlwind featured outputs displayed on a CRT, and a light pen to write data on the screen. Whirlwind’s success led to the United States Air Force’s Semi Automatic Ground Environment—SAGE—system and to many business computers and minicomputers.
1951-1958: SAGE Air Defense System
Project Whirlwind was integral to the development of the Semi-Automatic Ground Environment (SAGE) system, the first major real-time, computer-based command-and-control system. To create SAGE, Jay Forrester and others from the Project Whirlwind team moved off-campus to MIT’s new Lincoln Laboratory for defense research and development, forming the Digital Computer Division that was later spun off as Mitre Corp.
SAGE, conceived by Forrester and IEEE Fellow George Valley of Lincoln Laboratory, was designed as an air defense system to protect the United States from large-scale assault by long-range bombers and other weapons. It acquired data from geographically dispersed ground-based radars, sea-based radars on ocean platforms called Texas Towers, and airborne radars. The radar data was digitized and sent over telephone links to a central computer, which tracked the radar targets and could guide fighter-interceptors to engage intruding aircraft.
The computer’s job was to integrate a surveillance net consisting of large search, height-finding, and gap-filler radars, using telephone lines for data transfer to the central computer. From the radar target data, the computer created tracks showing the position and movement of enemy aircraft. It then formulated a response and sent messages to fighter aircraft so that they could intercept the targets. Initially, SAGE used the Whirlwind computer, the only one with sufficient speed.
Tracking data from multiple radars were displayed as icons on a CRT. When console operators pointed a gun-shaped light pen at an icon, the computer would display more information about the target’s track. Operators could then decide what action to take and send that information, together with the target’s track, to fighter planes and, later, to missiles.
The first version of SAGE, covering Cape Cod, Mass., and its environs, went operational in 1953. Once it had proved itself, the system was expanded to cover more of New England, with additional radars, better data processing at the radar sites, a more capable central computer (the IBM AN/FSQ-7 based on a Whirlwind II design, which was never built, and the first full-production computer with core memory). That computer was physically the largest ever built, using 55 000 vacuum tubes, weighing 250 metric tons, and requiring up to 3 megawatts. When SAGE became fully operational in 1963, it included 24 direction centers in the United States and Canada (each with a pair of the computers for redundancy) and three combat centers (each linked to more than 100 radar sites). SAGE remained in operation until 1983.
Although Lincoln Laboratory’s primary responsibility was to invent the needed command-and-control processes by using the newly emerging technology of digital computers, it also contributed many developments in radar technology required by the “clean” data demanded by the computer. They included improved moving-target-indicator circuitry and enhanced ability to withstand interference and jamming.
As the system evolved, SAGE broke new ground in radar, communications, computer, information display, computer programming, and networking techniques. SAGE not only revolutionized military command and control, but it also led to landmark advances in online systems and interactive computing, real-time computing, and data communications using modems.
SAGE contributed significantly to air traffic control systems, and it influenced the design of the U.S. Federal Aviation Administration’s air traffic system. It also led to the development, by IBM and American Airlines, of the SABRE airline reservation system.
The plaque commemorating this milestone was erected on 27 June in the main lobby of the MIT Lincoln Laboratory. The lobby leads to public spaces such as the cafeteria and the auditorium, where IEEE meetings and other events take place. It reads:
SAGE-Semi-Automatic Ground Environment, 1951–1958
In 1951 the Massachusetts Institute of Technology undertook the development of a continental air defense system for North America. The centerpiece of this defense system was a large digital computer originally developed at MIT. The MIT Lincoln Laboratory was formed to carry out the initial development of this system, and the first of some 23 SAGE control centers was completed in 1958. SAGE was the forerunner of today’s digital computer networks.