PART I — PHYSICAL ORIGINS

The Switch

At the bottom of the stack, there is no code. There are no functions. There are no "If" statements.

There is only Voltage and State.

Imagine you are holding a single electron. To you, it is just a unit of charge. But to a computer engineer, an electron is a problem. It is chaotic, it creates heat, and it moves probabilistically. To build a machine that can "think," we have to force this chaotic matter to behave. We have to beat it into submission.

The Valve of Reality

We do this using a device called the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Forget the name. Think of it as a Valve.

the same, but instead of water, we use electrons, and instead of a hand turning a handle, we use an electric field (Voltage) to squeeze the pipe shut.
(Note: The electrons do not flow into the gate; the field alone controls the channel.)

Lab 01: The N-Type Switch

Try the switch above. When you apply 5 Volts to the Gate, the valve opens. The "Source" connects to the "Drain", and current flows (The light turns on).

This simple action—flowing or blocking—is the only thing a computer can actually do. Everything else—from Grand Theft Auto to the AI reading this text—is just billions of these switches opening and closing in a very specific rhythm.

The Analog Failure

Why don't we use 2.5 Volts? Why only 0V and 5V? Because reality is noisy. If we tried to make a computer that understood "2.5", a tiny fluctuation in temperature or wire length might change it to "2.4", and the math would break.

Digital computing won because it is aggressive. It rounds everything. 4V? That's a 1. 3V? That's a 1. 0.5V? That's a 0. We tolerate the noise by ignoring it.

The Cost of Switching

There is one more catch. The valve does not open instantly. The Gate has Capacitance—it takes time to fill up with electrons before the field is strong enough to open the channel.

This Switching Delay is one of the fundamental speed limits of the universe. It is why your CPU cannot run at 100 GHz. We are waiting for the physics to settle.

Because switches take time to settle, computers must agree on when a value is valid. This agreement is enforced by a global rhythm — the Clock.

Hypothesis & Frequently Asked Questions

What if we could switch infinitely fast?

If switching had zero specific delay, clock speeds would skyrocket to the terahertz range. However, we would hit the next wall: the speed of light. Even if the switch works instantly, the signal still takes time to travel down the wire to the next switch. We are trapped by geometry.

Why 5 Volts? Why not 100 Volts?

Higher voltage means faster switching (stronger field) and less noise susceptibility, but it also means Quadratically Higher Heat (P = V² / R). Using 100V would melt the silicon instantly. Modern CPUs actually use ~1.0V or less to minimize heat.

Are Quantum Computers faster because they ignore this?

No. Quantum computers are not "faster" in terms of raw clock speed; in fact, their gate operations are often much slower than silicon (milliseconds vs nanoseconds). They are "faster" because they use a different math (superposition) that allows them to solve specific problems in fewer steps.

Why is the Gate called a Capacitor?

Because it literally is one. It is a sandwich of Conductor (Gate) - Insulator (Oxide) - Conductor (Body). To turn it on, you have to fill this capacitor with charge. That filling process takes time, and that is where the latency comes from.

What happens if I undervolt my CPU?

If you lower the voltage, you reduce the force pushing electrons. The switches open slower. If they open too slow, they might not finish switching before the next clock cycle hits. The computer will read a "0" when it should have been a "1" (because it was only half-full), and your system will crash (Blue Screen).