FREE LESSON · Physics & signals · 1 OF 4
What Is a Bit in Computer Science?
A bit is a physical agreement — Stable distinctions in a noisy world
Zero and one are regions, not perfect voltages.
A physical device exposes a continuous quantity such as voltage, charge, light, or magnetization. Engineers assign ranges of that quantity to symbols. A receiver uses thresholds to decide which symbol arrived; the unused gap between valid ranges provides a noise margin.
Digital reliability comes from restoring a symbol at boundaries, not from eliminating analog physics.
Regeneration breaks the accumulation of small errors
Suppose 0–0.8 V means low and 2–3.3 V means high. A gate receiving 2.7 V does not forward “2.7” as an increasingly degraded fact; it produces a fresh high-level output. Cascaded gates therefore restore logical levels, within their timing and electrical limits.
Regeneration is why billions of imperfect analog devices can implement long digital computations.