Analog computers represent a class of computational devices that utilize continuously varying physical quantities to represent and solve mathematical problems. Originating from ancient tools like the abacus and astrolabe, modern analog computers became prominent during the early to mid-20th century, serving crucial roles in scientific research, engineering, and military applications. These machines operate based on analog signals, typically using electrical voltages, mechanical systems, or hydraulic flows to simulate and model real-world scenarios. So what the blaze is an Analog Computer? In this article we’ll briefly examine the Analog Computer and how it works.
Below is a selected timeline of Analog Computing innovation of some of the early devices that have fallen out of favor. Instead, we use digital computers everywhere, but there is a resurgence with new Analog computing companies developing technologies that utilize silicon and not water, valves, or mechanics to perform their computations. Indeed, machine learning is creating renewed interest in Analog Computing for neural network computing.
The Astrolabe: An Ancient Marvel of Astronomy and Navigation
The astrolabe, a sophisticated instrument with its roots in ancient Greece, stands as one of the most significant tools in astronomy, navigation, and timekeeping. Its name derives from the Greek words “astēr” (star) and “lab-” (to take or hold), which aptly describes its primary function: capturing the position of celestial bodies.
In terms of its operation, the astrolabe is undeniably analog. Analog devices work by representing data through continuous physical quantities, and the astrolabe does this by physically modeling the sky. When using the astrolabe, an observer aligns the rete with the stars, essentially creating a scaled-down representation of the celestial sphere. The various scales and markings on the instrument then enable the user to deduce information such as the time, latitude, or the position of a particular star or planet. This direct, physical interaction and representation of data are hallmarks of analog devices.
Beyond its technical marvel, the astrolabe holds significant cultural and historical importance. It bridged the worlds of astronomy and navigation, enabling sailors to chart their courses with greater accuracy and scholars to delve deeper into the mysteries of the cosmos. Its intricate design, combined with its profound utility, embodies the synthesis of art and science that was characteristic of many ancient civilizations. As an analog instrument, the astrolabe stands as a testament to humanity’s timeless quest to understand and connect with the vast expanse of the universe.
Antikythera Mechanism (c. 150~100 BC)
The Antikythera Mechanism is one of the earliest analog computing devices, dating back to the Hellenistic period. Although the exact inventor remains unknown, this ancient Greek artifact demonstrated an unparalleled level of complexity at the time. The mechanism was used to predict astronomical positions and eclipses for calendrical and astrological purposes, showcasing the early human endeavor to solve complex problems using mechanical computation1.
The discovery of the Antikythera Mechanism in 1901, in a shipwreck off the Greek island of Antikythera, provides a fascinating glimpse into the ancient world’s technological capabilities. The intricacy and functionality of the mechanism wouldn’t reappear until many centuries later, making it a remarkable piece of history that highlights the long-standing human quest for computational tools.
Tide Predictor (1873) by William Thomson (Lord Kelvin)
Lord Kelvin’s Tide Predictor was a significant development in the realm of analog computing during the 19th century. This machine was designed to predict tidal motions, which was crucial for naval and maritime activities. The ability to forecast tides accurately was a testament to the potential of mechanical analog computing in solving real-world problems2.
The Tide Predictor’s mechanical design involved a set of pulleys and gears that could simulate the movements of tides based on lunar and solar cycles. The success of this machine underscored the practical applications of analog computers in scientific and engineering fields, paving the way for further innovations in analog computation.
Harmonic Analyzer (1898) by A.A. Michelson and S.W. Stratton
The harmonic analyzer developed by Michelson and Stratton was another significant milestone in the history of analog computers. This machine, comprising 80 components, could generate sinusoidal motions, which could then be manipulated to solve mathematical problems. The ability to produce and analyze harmonic motions showcased the growing sophistication and utility of analog computing devices.
The Harmonic Analyzer’s design allowed for the multiplication of sinusoidal motions by constant factors through the adjustment of a fulcrum on levers. This capability demonstrated a step forward in the complexity and functionality of analog computers, expanding the scope of problems that could be tackled using mechanical computation.
Dumaresq (c. 1902) by Lieutenant John Dumaresq
The Dumaresq was a mechanical calculating device invented around 1902 by Lieutenant John Dumaresq of the Royal Navy. This analog computer related vital variables of the fire control problem to the movement of one’s own ship and that of a target ship. Used often with devices like the Vickers range clock, it aided in generating range and deflection data to continuously set the gun sights of the ship, showcasing the practical application of analog computers in military operations.
As development proceeded, a number of versions of the Dumaresq were produced, each of increasing complexity. This trend illustrated the evolving capabilities of analog computers and their adaptability to the changing needs of warfare and navigation, showcasing the potential of analog computation in solving real-world problems.
Arthur Pollen’s Analog Computer (c. 1912)
By 1912, Arthur Pollen had developed an electrically driven mechanical analog computer for fire-control systems based on the differential analyzer. This invention was utilized by the Imperial Russian Navy during World War I, marking one of the early instances where analog computation was applied in military technology. The development and deployment of this analog computer highlighted the growing importance of computation in modern warfare and showcased the potential advantages of analog computers in real-time problem solving1.
The utilization of Pollen’s analog computer during a significant period of global conflict underscored the strategic advantage conferred by computational technologies. It also demonstrated the growing intersection between military needs and technological innovation, a trend that would continue through the 20th century.
Analog Computer: AC Network Analyzers (Starting 1929)
Starting in 1929, AC network analyzers were constructed to tackle calculation problems related to electrical power systems that were too large to solve with numerical methods at the time. These machines essentially acted as scale models of the electrical properties of full-size systems, aiding in the solution of problems in nuclear physics and structural design among other fields. By the end of the 1950s, over 50 large network analyzers were built, indicating the significance and wide adoption of these analog computers1.
AC network analyzers showcased the potential of analog computers in handling large-scale computational problems. Their development and utilization marked a significant period in the history of analog computing, demonstrating the versatility and practical utility of analog computation in addressing complex engineering and scientific challenges.
Differential Analyzer (early 1930s) by Vannevar Bush
Vannevar Bush’s Differential Analyzer marked a notable advancement in the development of analog computers. This machine was capable of solving differential equations using mechanical integrators, bridging the gap between theoretical mathematics and practical computation. The Differential Analyzer was the first practical and reliable device of its kind, showcasing the evolving capabilities of analog computers2.
The invention of the Differential Analyzer also highlighted the growing collaboration between engineering and mathematics in the quest for better computational tools. This machine’s success paved the way for further innovations in analog computing, broadening the horizon for what could be achieved with mechanical and, later, electronic analog computation.
These machines and inventors played pivotal roles in the progression of analog computing, each contributing unique advancements that pushed the boundaries of what could be accomplished with analog computation. Through their innovations, the landscape of computing was forever altered, paving the way for the digital revolution that would follow.
Turing-Welchman Bombe (c. 1940) by Alan Turing and Gordon Welchman
The Turing-Welchman Bombe was a mechanical computer designed by Alan Turing and Gordon Welchman to help the British crack encrypted German military messages during World War II. This device played a crucial role in the war effort, aiding in deciphering encoded messages and providing invaluable intelligence to the Allies. The Bombe epitomizes mechanical and logical ingenuity, showcasing how analog computation could be employed in cryptanalysis to solve complex code-breaking problems.
The success of the Turing-Welchman Bombe underscored the strategic importance of computation in modern warfare. It also highlighted the potential of analog computers in tackling intricate problems, marking a significant chapter in the history of analog computing. The Bombe’s legacy continues to be celebrated as a monumental achievement in computing and cryptography.
Electronic Differential Analyzer (EDA)
The Electronic Differential Analyzer (EDA) was one of the earliest electronic analog computers developed during the World War II era. Unlike its predecessor, the mechanical differential analyzer, the EDA utilized electronic components, predominantly vacuum tubes, to perform its calculations. This shift to electronic components made it faster and more reliable than its mechanical counterpart. One of its primary use-cases was in solving differential equations related to the trajectory of artillery shells. This allowed for more accurate targeting during wartime operations. Additionally, the EDA was employed in various scientific and engineering tasks, such as studying electrical systems and heat conduction.
Moniac (Monetary National Income Analogue Computer)
The Moniac, also known as the Phillips Hydraulic Computer, was a unique analog computer designed by William Phillips in 1949. Instead of electronic components, it used water flowing through a series of tanks and pipes to simulate the behavior of a nation’s economy. The flow of water represented the flow of money, allowing economists and students to visualize economic processes and the interplay between various economic variables. Its primary use-case was in education and economic research. By adjusting the flow rates and observing the effects on the ‘economy,’ users could gain insights into the potential outcomes of economic policy decisions and changes in the market.
Heath Robinson
The Heath Robinson was an early analog computer developed during World War II by the British. Named humorously after the British cartoonist known for illustrating overly complex machines, this computer was designed to tackle the challenge of deciphering encrypted German communications, specifically the Lorenz cipher. The Heath Robinson was not entirely electronic; it combined both mechanical and electronic components. Its primary use case was in code-breaking. By running punched tapes containing ciphered messages, it attempted to find the original settings of the Lorenz machine used to encrypt the messages, thus aiding the decryption process. Although it had reliability issues due to its mechanical parts, the Heath Robinson paved the way for more advanced decryption machines like the Colossus.
Rockefeller Differential Analyzer
The Rockefeller Differential Analyzer, developed in the late 1930s and early 1940s, was another significant electronic analog computer of that era. Based on the principles of the differential analyzer designed by Vannevar Bush, this machine was an improvement over its predecessors, with enhanced accuracy and speed. The primary use-case for the Rockefeller Differential Analyzer was in scientific research. It was used for solving complex mathematical problems in physics, engineering, and other scientific fields, aiding researchers in understanding phenomena and making predictions based on mathematical models.
Electronic Associates TR-10 Analog Computer
The Electronic Associates TR-10 Analog Computer, introduced in the early 1960s, was another milestone in the evolution of analog computing. With its modular design, the TR-10 offered flexibility and scalability, enabling users to configure the system based on specific needs.
One notable use-case of the TR-10 was in the field of control systems engineering. The computer was able to simulate feedback control systems, helping engineers optimize their designs. By modeling these systems on the TR-10, engineers could anticipate potential issues and make necessary adjustments before actual implementation.
Furthermore, the TR-10 found applications in the academic world. Many universities incorporated the machine into their engineering curricula, using it as a teaching tool for students to gain hands-on experience with system simulations. It played a pivotal role in training the next generation of engineers by providing a practical understanding of various engineering principles.
The Analog Computer
Thanks for joining us on this remarkable journey. It’s too easy to think that computers have always been digital, but Analog Computers have been with us far longer. So prepare for yet another revolution in computing technology, but this time, it’s the Analog Computer that might be taking the Glory.
