Digital logic as we know it today required collaboration from thousands of people over thousands of years.

Before electronic devices were ever created, mathematicians and philosophers were unknowingly creating the language of binary and laying the foundation for modern computing devices. These concepts were later applied to similar communication systems like Morse Code and the binary that we’re familiar with today. Mathematicians like George Boole and Charles Babbage applied these concepts to mechanical devices to automate them. While computing has a rich history, the logic gates that allow computers to function get less attention.

Ancient Logic and Binary

In the 10th century in ancient China, a scholar named Shao Yong rearranged the hexagrams from the I Ching into a format similar to binary. Some scholars even suggest that the I Ching was Gottfried Leibniz’s inspiration for binary code.

Ancient number systems compared with Leibniz’s binary, made by CounterComplex

There were also truth tables in ancient Greece with YES and NO functioning like ON and OFF in the case of transistors. Leibniz most likely found inspiration from Greek mathematicians because their works were the most accessible for scholars in Europe during the 17th and 18th centuries.

There was also the small, remote Polynesian island of Mangareva which used a binary numeral system to help with mental arithmetic. Many ancient civilizations had numeric systems with similarities to binary as we know it today. Whether Leibniz was inspired by one of these other ancient systems will remain one of history's mysteries. The study of ancient mathematics and binary is very interesting, but it also helps to temper one's expectations and be prepared for misleading headlines and titles.

From Mechanical to Digital Logic

Although Gottfried Wilhelm Leibniz is credited with inventing binary as we know it today, the first logic based devices were created by Charles Babbage. His first Difference Engine was a mechanical calculator designed to tabulate polynomial equations and print the results on a roll of paper.

In Babbage’s design, mechanical gears served the function of logic gates. He designed a second Difference Engine, also referred to as the Analytical Engine, but could never obtain funding to make it. His designs were later noticed in the 1980s and a fully functional model was finally created to his specifications.

The first common logic gates were electromagnetic relays, which were basically ON-OFF switches. The electromechanical relay was invented by Joseph Henry in 1835, but the brilliance of his invention was not realized until later when his relays were used in the telegraph. After the invention of the rotary dial in 1890, more complex relays with 10 positions were developed.

In 1898, Nikola Tesla filed a patent for an invention he called “teleautomation”, which he demonstrated with a radio-controlled miniature boat, the first remote control device ever made. The remote control system contained a method for decoding Hertzian waves. This system would toggle actions based on different signals, functioning as an AND gate.

The first digital, programmable computing devices’ logic circuitry laid in vacuum tubes. This includes famous computers like ENIAC, Colossus, and Alan Turing’s Pilot Ace. These early digital computers were enormous and had thousands of vacuum tubes. In order to make computing devices accessible to the public, the logic circuitry would need to shrink.

ENIAC occupied 1600 square feet of space. A modern smartphone has about 12,000 times as much computing power. Courtesy of the US Army

This needed decrease in size came in the 1960s with resistor-transistor logic (RTL) and transistor-transistor logic (TTL). RTLs were the first logic devices to be incorporated into integrated circuits and were later used in the Apollo guidance computer. The first TTL integrated circuits were developed in 1963 by Sylvania and were popularized by TI’s 7400 series. Since then, modern logic circuitry has been shrinking these concepts and adding additional Boolean gates.

Digital Logic Today

Centuries of innovation have led to tiny and powerful logic devices like FPGAs, PLCs, and Pico Gates, which allow tiny devices to have computing power and control functionality that dwarfs the massive computers of old. These days, there are tiny logic packages for just about every function imaginable, whether it comes in an array or a discrete package.

If you’d like to learn more about how discrete logic packages are being miniaturized, Tom Wolf, a senior product application engineer at Nexperia will be hosting a free webinar on June 22nd at 9:00 AM Pacific Time.

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