Introduction
Any attempt to answer the question “what analog[ue] technologies […] are part of/at the roots of [(ALL)] digital technology” will, for certain, raise a number of controversies. Nevertheless, in this blog post, I will attempt to demarcate the “digital” in the world of computing (the world of computing is what you might refer to as the “digital” instead), and try and locate the “digital” in the vast world of interconnected digital and analogue electronic circuits. Once the “digital” is successfully demarcated, identifying those components of the computing world that are analogue becomes a simple matter.
Hardware
To begin with, term “digital” refers to a certain way of encoding information in electronic circuits that are parts of digital devices (computers, smart phones, feature phones, modems, printers, DSLRs, …), such that there may either be a direct current (DC, as in ACϟDC, the guys from the album High Voltage) flowing through a component of the circuit, or not. A DC signal is characterised by a constant voltage across a certain component during the periods where an electric current is flowing, and represents number “1” in computing. On the other hand, “0” is represented by “no signal”, 0 V current, or no current at all. In this simulation, the square wave generator’s output signal causes the red light emitting diode (LED) to toggle on and off. Alternatively, the oscilloscope at the bottom sketches the signal that is the output of the signal generator (the square wave generator) and the input of the red LED; the signal that flows through the circuit. The periods where the red LED is switched on, which corresponds to the periods where a 5 V direct current is flowing through the circuit (see the oscilloscope), represent number “1” in computing. On the other hand, the periods where the red LED is switched off, which corresponds to the periods where no current is flowing through the circuit, “no signal”, or 0 V, represent number “0”. Now, the crucial question concerns the manner by which a direct current is generated to obtain number “1”. (There is no need to generate number “0” electronically/digitally. All you have to do is switch off your device/power supply!)
Remember that in order for a computer/laptop/PC/Mac/notebook to boot, the device’s battery must be charged, or the device itself must be plugged in. In the former case, the device would be operating using a DC power supply. In the latter case, however, the device would be operating using an alternating current (AC, as in ACϟDC, the guys from the album Power Up) power supply. First, to understand how an alternating current might look like, which is an analogue signal, not digital, please follow this link. Note how the lamp’s intensity changes gradually over time (Yellow: high intensity, Red: medium, Black: no light). Now the question concerns the manner by which an AC current is converted to a DC current.
In short, that may simply be accomplished by acquiring an AC/DC converter (not the band, whose name may be distinguished by the “lightning bolt representing the slash” (AC/DC Trademark of Leidseplein Presse B.V. – Registration Number 4921246 – Serial Number 86551440, 2024)), which is available online as a circuit component, or as a standalone device. In this simulation, the internal working of the full wave rectifier is demonstrated. A full wave rectifier is the circuit component that is responsible for AC/DC conversion. In the simulation, at the bottom, two oscilloscopes are found. The first oscilloscope, to the left, sketches the output of the signal generator, an AC signal. The second oscilloscope, to the right, sketches the signal that flows through the red LED. Note how the signal in the second oscilloscope resembles a direct current, and that the red LED keeps emitting light constantly over time.
Consequently. It may be concluded that the full wave rectifier demarcates the “digital” in the world of computing, such that all components operating on alternating currents are the analogue components, and the rest of the components, on the other side of the rectifier, are part of the “digital”. However, note that the resulting DC signal is not perfectly flat as it should. Though, the perfect shape may still be achieved by clipping the signal, using, yet, analogue components on the digital side of the circuit. In fact, all circuit components involved at both sides, the digital side and the analogue side, are analogue components. The only components that may be said to be digital are the logical gates in the circuit, which, eventually, are also composed of analogue parts internally, as the AND gate demonstrated in this simulation. (This is a rough design, not the best.)
Therefore, it may be said that digital technology is, simply put, analogue at heart, and that, in fact, no digital device exists effectively. Yes, the direct current (roughly) exists. However, just as computing is all about serialisation and deserialisation (transforming human-readable information into zeros and ones, and vice versa), the direct current originates from an alternating current, AC/DC conversion. And even if a device is operating on DC power, when your computer is not plugged in, the circuit is full of components aimed at protecting the individual “digital” components, and these components are all analogue in nature, as demonstrated in the AND gate simulation above. As a last resort, the “digital” may be said to be a special case of the “analogue”, if it ever existed in the first place, a statement which sounds contradictory.
An alternative approach
An alternative approach to demarcate the “digital” is inspired by the division of the major areas of study concerned with computing:
- computer science, the study of computer software;
- computer engineering, the study of computer hardware (my area of study, 🫡💪✊, we beat the rest by the way); and
- telecommunications engineering, another field of study that focuses on the hardware part of computing, with a twist in the tale.
To better demonstrate the difference between computer science, on the one hand, and computer engineering and telecommunications engineering, on the other hand, two analogies (!) are in place.
Just as a human has (supposedly, I do not believe in fairy tales) two sides, the body and the soul, so does a computer. The hardware side of the computer is the device, the circuit, the things that may be sensed by hand. The computer case for instance, or the mouse. The software side of the computer is the intangible part, the part that does not exist: programs, or applications, the operating system, and the like, all of which are simply digital signals that have been previously established to be analogue in nature. (Yes there are screen-touch devices, however, you do not touch a program!) An alternative analogy is inspired from much more mature fields (as opposed to religion): psychology and neurology, where software corresponds to the psychological realm (realm?! really? although it does not really exist!), and where hardware corresponds to neurology.
Now that the second attempt to locate the “digital” has failed, it may be safely concluded, assuming that the “digital” may not be located by other means, that all technology is analogue, whether analogue or digital, and that the “digital” does not even exist as imagined. The digital is simply a concept: an ideal, utopian world where “1” is a perfectly flat signal at 5 V (in most instances), and where when the amplitude of the signal drops to “0”, it does so perfectly, instantaneously, with no delays whatsoever, and with a 90 degrees angle. Two requirements that may never be met given the current state of technology, however simulated to a certain extent.
Disclaimer
The title of this blog post is inspired by a song by Judas Priest.
References
AC/DC Trademark of Leidseplein Presse B.V. – Registration Number 4921246 – Serial Number 86551440: Justia Trademarks. (2024, October 4). http://trademarks.justia.com/865/51/ac-86551440.html
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