Introduction to Digital Electronics

Back to Digital Electronics
Arjit Sharma
02 Mins

Computers started as bulky machines with vacuum tubes and punch cards. They used to “compute” things using wires and switches.

Early Computation: A World of Switches and Cards

In the 1930s and 40s, machines like the ENIAC (Electronic Numerical Integrator and Computer) performed basic arithmetic using vacuum tubes, which acted like electrical switches. A switch is a electrical component where 1=ON and 0=OFF. These ON/OFF states became the earliest form of binary data.

At the same time, punch cards were used to input data and even programs. Each card had rows and columns where holes could be punched, each hole representing a 1(ON).

Example -

An early program to compute A = B + C would involve:

  1. Punching B and C onto cards.
  2. Feeding the cards into a reader.
  3. Using vacuum tube circuits to add the numbers.
  4. Printing or punching the result onto a new card.

It was brilliant for its time but incredibly rigid. Without a formal system, engineers guessed how to wire switches to achieve desired logic (e.g., “if A and B are ON, output C”). They tested combinations manually, often rebuilding circuits if logic failed.

Claude Shannon’s Breakthrough: Turning Logic into Math

In 1937, a 21-year-old graduate student at MIT named Claude Shannon changed everything. In his master’s thesis, he made a simple yet revolutionary claim

“ You can design and simplify electrical circuits using Boolean algebra. ”

Now engineers could design complex circuits on paper with equations first and then build confidently. This is what made modern computing possible.

From Switches to Chips

Thanks to Shannon’s foundational work, engineers could now build logic gates (AND, OR, NOT) from vacuum tubes.

In 1947, a transistor was developed which was a small semiconductor device that could also represent 1 or 0. Later Integrated circuits were built which housed many transistors and then microprocessors, but the concept they followed remained same that was binary logic.

Analog vs. Digital: Why Binary Won

analog-and-digital

Before digital electronics, many systems were analog working with smooth, continuous values but analog systems were sensitive to noise.

Digital electronics, using just two states (0 and 1), were:

  • Reliable: Clear, noise-resistant signals.
  • Scalable: Easy to build complex circuits.
  • Perfect for logic: Ideal for computation, storage, and data processing.

Shannon’s math-based design approach perfectly matched the binary nature of switches (relays, vaccum tubes and later transistors), enabling precise, mathematical circuit design.

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