History of Human-Machine Interfaces. Part 1: The Pre-Computer Era

Trace the evolution of human-machine interfaces from mechanical levers and gears to early electronic computing machines and developments in speech synthesis. The story about the fundamental principles of human-machine interaction throughout history that laid the groundwork for modern interfaces.

History of Human-Machine Interfaces. Part 1: The Pre-Computer Era

The foundations of human-machine interaction were laid in the era of the first tools and mechanisms. In the pre-computer era, human-machine interfaces were limited to mechanical and analog devices, but even then they reflected the principle of necessary diversity formulated later by cyberneticians.

This principle states that the richer the range of control of an information system and the more precisely the control actions are coordinated, the greater the efficiency and adaptability of the system. In the context of interface development, this emphasizes the critical importance of creating solutions intuitive to users and capable of performing complex tasks.

The term "interface" in this historical account goes beyond simple human-computer interaction to encompass the entire arsenal of tools, mechanisms, and techniques that have enabled humans to control machines and processes. Interfaces built bridges between the physical and mechanical worlds, both by means of input tools - levers, buttons, and keys - and by means of information displays - pointers, scales, and audible signals.

Since ancient times, interfaces have been divided into professional and consumer interfaces, each reflecting different user knowledge and skills requirements. From command lines requiring specialized expertise to intuitive search engines and devices accessible to everyone, the evolution of interfaces demonstrates the constant desire to simplify human interaction with technology.

The clavicetrium in an engraving from M. Pretorius' treatise Syntagma Musicum (1615-19) is one of the earliest depictions of keyboard musical instruments
Mixing consoles require the sound engineer to know a huge number of functions, buttons, and sliders, each responsible for a specific aspect of the sound, which is not available without specialized training

With this article, we begin a journey back in time, exploring how primary mechanical devices and early technological solutions formed the basis for today's interaction systems. We will start with the pre-computer era when keys and locks carried a physical function and symbolized ideas of security and access. Every tool and mechanism had an immediate, tangible meaning. Immersing ourselves in this era will help us understand how the fundamental principles of human-machine interaction remain relevant today despite dramatic changes in technology and design approaches.

Simple mechanisms for interacting with machines in the pre-computer era

Multiplication of physical force. Many early human-machine interfaces were based on simple mechanisms such as levers, blocks, and gears that played a crucial role in the development of civilization. These elements not only multiplied human physical strength but also opened up new possibilities for construction, transportation, and military technology. Using these mechanisms in ancient lifting devices and water lifting mechanisms does not simply demonstrate early principles of force transmission and amplification; it laid the foundation for the subsequent development of engineering and mechanics.

A simple action, turning a barrel organ knob, causes a complex program to cycle through a polyphonic melody. Once found, the mechanics often find their way into a wide variety of solutions (Source)
Nostalgia for interfaces leads to products with something unusual about them being shot. Thus, the indie project Playdate, a portable game console from Panic and Teenage Engineering, has gained popularity due to its design and the unusual mechanics of the lever arm, which is used as one of the input devices

Information Display. In the pre-computer era, information display mechanisms were closely associated with using various indicators such as scales and hands. Compasses, astrolabes, sundials, water clocks, and mechanical clocks used these elements to provide visually perceptible information about physical quantities such as time, distance, and speed. The scales and hands on these devices allowed people to visually evaluate and interpret the measured parameters, enabling effective navigation, planning, and coordination of activities. Thus, these elements acted as critical components of early information interfaces

Mechanical computers and musical instruments demonstrate the principle that form follows function. These devices are designed so that their structure and control mechanisms mimic the principles of what they are intended to measure or control. For example, the division of a score in an abacus or the arrangement of keys on musical instruments reflects the digitization of numbers or octaves in music, emphasizing how the device is adapted to control a particular order or structure. That is, the physical structure of devices is directly related to their functional purpose. Visual and tactile design serves to better understand and interact with measurable and controllable phenomena.

Reconstruction of a Roman abacus. The abacus, calculators, and many other examples of similar computational tools serve as examples of prototypical computational devices in which the interface of the system is maximally merged with the mechanism and process of computation itself
Smart calculator on Apple Watch - The Plusly app lets you interact with calculation items with your finger

Automation: forward and feedback. Transportation and industrial devices such as steam locomotives and textile machines demonstrate the development of human-machine interfaces in the context of forward and feedback. Controlling these machines required operators to understand control mechanisms and interpret feedback signals, enabling real-time adaptation and adjustment. This interaction not only contributed to improved operational efficiency and safety but also laid the groundwork for the development of the control systems and interfaces of the future.

Predecessors of text-based interfaces. The typewriter, first invented in the 19th century, was one of the key technological breakthroughs in the history of human-machine interaction. It provided the ability to convert thoughts into printed text rapidly and standardized, greatly speeding up and simplifying the process of creating documents, letters, and literary works. The typewriter interface, while requiring some skill to use effectively, was intuitive and allowed users to see their actions' results on paper immediately. This immediate feedback between action (pressing a key) and reaction (the appearance of a symbol on paper) is a fundamental principle of many modern interfaces.

Security interfaces. The key-lock mechanism can be seen as one of the oldest analogs of security interfaces for controlling access to something. This system is a primitive form of user authentication, where the key serves as a physical "password" that authorizes or denies interaction with the lock. The concept of privacy and security remains relevant in today's technological interfaces. We can even use a hardware security key physically attached to the device.

Medieval Gothic iron castle of the 15th-16th centuries, Metropolitan Museum of Art (New York) (source)
Keychain is seen as a persistent metaphor for access to a variety of systems, such as in the macOS application KeyChain

Coding and signaling systems. Ancient signaling systems, such as transmitting messages through signal lights or semaphores, were used to communicate over long distances long before the invention of electrical devices. These methods relied on visual perception and required the sender and receiver to know a predetermined code (e.g., a certain number of lights or the hand position of a semaphore could signify a particular message).

The telegraph revolutionized long-distance communication by enabling instantaneous transmission of messages over long distances using electrical signals. The Morse system, adopted to encode messages, was one of the first standardized interfaces for human-machine interaction, where short and long signals (dots and dashes) were combined to represent letters and numbers. The telegraph demonstrates an important step in the evolution of interfaces, where a mechanical action (pressing a key) is converted into an electrical signal, which is then interpreted as a text message.

German Enigma cipher machines, used to encrypt and decrypt secret messages since the 1920s in commercial and military communications. They were most widely used in Hitler's Germany during World War II. Each new version involved an increasingly complex process of decrypting messages without a key
Bombe at the British cryptographic center Bletchley Park, 2004 - an electromechanical machine for deciphering the Enigma code, the theoretical work on which was done by Alan Turing

Punched cards were one of the earliest ways to input data and programs into computing systems. Punched cards were rectangular cards made of heavy paper or cardboard. Data was entered into them manually using a special device called a punch card. The operator placed a blank card in the puncher and pressed the keys arranged like a conventional typewriter. Each key press controlled a die that punched a hole at the appropriate position on the card. The positions of the holes were strictly defined, and various information, such as numbers, letters, commands, etc., were encoded.

Typically, a punch card had 80 or 96 columns (columns), in each of which one of several holes representing numbers or letters could be punched. Combinations of holes in different columns made up the encoded data. In modern linters we can find similar limitations on the number of columns of program code.

Special devices — punch card readers or simply readers — were used to read data from punch cards. They literally "read" the location of the holes by means of metal pins passing through the holes, translating the physical holes into electrical signals that could be processed by computers.

The U.S. Census Bureau employee on the left prepares punch cards using one of the first pantographs, while the employee on the right uses an improved 1930s punch card that performs the same task faster (source)
A 2020 U.S. Census paper form with a prepaid envelope for returning a completed form (source). The rigorous structure of the forms reduces errors in the image recognition process. Recognizing handwritten digits, as in field 4 for a phone number, was one of the first breakthroughs in image recognition

Although primitive by today's standards, the punch card interface marked an important step in developing data entry methods. Punched cards made automating the data entry process possible, replacing manual input entirely. They were widely used in the 1960s and 1970s to program early computers.

Analog computing machines

Analog computers were early mechanical and electronic systems used to model and solve complex mathematical problems by physically manipulating quantities. These computing devices used continuous physical processes, such as gears' rotation, fluid flow, or voltage changes, to represent and process numerical values.

Lord Kelvin's tidal integrator in the form of balls and disks. The ratios introduced were changed by moving the balls left or right along the upper beam. A mechanical computer was used by a scientist to study tides (source)

The differential analyzer, developed by Vannevar Bush in the 1930s at the Massachusetts Institute of Technology, was one of the best-known mechanical analog computers. This device consisted of a complex system of integrated components, including torsion drives, differential mechanisms, and automatic recording devices. Users could set the initial values of variables and the relationships between them using mechanical levers, buttons, and scales. The computer calculated the results, displaying them on rotating graphs and charts. This interface allowed researchers to visualize and analyze complex mathematical relationships using the mechanical analogy of motion and relationships between components.  

Analog computing machines, popular in the 1940s and 1950s, used electronic components such as operational amplifiers to simulate differential equations and other mathematical concepts. Users set initial conditions and parameters using potentiometers, switches, and other manual controls. Computational results were displayed on oscilloscopes and arrow indicators. These electronic computers provided greater accuracy and speed of computation than their mechanical counterparts, but their interfaces were still based on physical representations of quantities and required a thorough understanding of mathematical principles for effective use.

First approaches to the realization of human-machine interaction in the 1940s-50s

The ENIAC was the first general-purpose electronic digital computer that could be reprogrammed for various tasks. The computer was implemented on electronic tubes and was essentially an electronic version of a large mechanical digital analyzer. The architecture of the computer appeared during World War II as a solution for computational problems associated with the adoption of new types of weapons, taking into account their firing quality, and later - as a calculation machine for the tasks of modeling a thermonuclear explosion. In fact, the machine was intended for solving mathematical differential equations. Intermediate results were displayed on punched cards and after recomputation were again entered into the machine.

Two operators are engaged in the ENIAC programming process (Source)

The mid-twentieth century ushered in an era of research in human-machine interaction that opened the door to developing systems that could mimic the human mind and associative thinking. One of the early breakthroughs was Vannevar Bush's article "As We May Think," published in 1945, which presented the concept of a hypertext system. This system, called Memex, was envisioned as a device for storing vast amounts of information and retrieving it conveniently, which could radically improve knowledge management.

Bush proposed the use of electromechanical mechanisms to control reading and writing on microfilm, which allowed the user not just to save documents and notes but also to create complex networks of associative links between them. This idea, anticipating modern hypertext and Internet technologies, emphasized the importance of convenient access to and organization of information.

An article titled by Vanivar Bush presents a mechanism for adding information to the system using electromechanically controlled cameras and creating linked ultra-high resolution microfilm recordings (source)
Memex is a system idea further proposed by Bush. It is, in fact, a table with projected, linked, and copied microfilms

The generation of sounds close to speech began to be solved in the 30s-40s. The first major breakthrough was the Voder. The machine synthesized human speech by mimicking the effects of the human speech pathway. Using a handle on the wrist a system of keys, the operator could simulate consonant and vowel sounds, controlling the pitch of the sound with a foot pedal. It was a difficult machine to operate, but after several months of practice, a trained operator could produce recognizable speech.

Schematic diagram of Voder speech synthesizer operation

A notable alternative to controlling devices via keys and buttons was voice control, which began to take hold in the 1950s, when the first attempts at voice control of computers were made. One of the pioneers was Audrey, a system developed in 1952 by Bell Labs engineers.

Bell Labs Audrey demonstration, 1952. The system converts a spoken word into one of ten digits

The Audrey system could determine the digits from 0 to 9 with an accuracy of 98%. This was a real breakthrough for that time - the first transistor computers appeared only in the second half of the fifties.

Demonstration of the ShoeBox, an advanced version of Audrey that came out a decade later

Conclusion

By looking at the evolution of human-machine interfaces in the pre-computer era, we can trace a continuous drive toward ever more natural, intuitive, and powerful means of interaction. Early interfaces, such as levers, blocks, and gears, provided humans with the ability to amplify and direct their physical abilities with the help of machines. As technology evolved, interfaces began to extend beyond mechanical systems to include methods of information exchange, authentication, data display, and even the rudiments of programming.

We are now seeing ever closer integration of man and machine, where interfaces are becoming virtually invisible, allowing natural interaction through voice commands, gestures, and even neural signals. Such aspirations are going in the direction described in science fiction in the 40s and 60s.

The development of interfaces not only expands the possibilities of interaction but also has a profound impact on human nature itself. Interfaces shape the way we perceive and interact with the world around us, changing our habits, behaviors, and cognitive abilities. The design of new interfaces must take into account both technical and social, ethical and humanistic aspects to ensure the harmonious coexistence of man and machine in the endlessly evolving world of technology.