Core idea of digital systems: Do digital systems operate exclusively on discrete symbols (digits), such as codes representing numbers, letters, or control symbols, rather than continuously variable quantities?

Introduction / Context:
Digital electronics encodes information as discrete symbols—usually two levels labelled 0 and 1, but sometimes multi-level codes. These symbols represent numbers, letters, and control characters, enabling robust processing with noise margins. This question confirms the fundamental distinction between digital and analog domains.

Given Data / Assumptions:

• Digital signals are quantized into discrete states.
• Analog signals vary continuously and require conversion to be processed digitally.
• Codes like ASCII or BCD map symbols to binary patterns.

Concept / Approach:
Digital systems internally manipulate discrete symbols using logic gates, registers, and finite-state machines. Even when interfacing with the analog world (sensors/actuators), conversion stages (ADC/DAC) bridge the domains so the core system still processes discrete values, not continuous waveforms directly.

Step-by-Step Solution:

Verification / Alternative check:
Inspect a microcontroller diagram: ALU, registers, data buses, and instruction decoders all operate on fixed-width binary words—discrete symbols. Only dedicated analog blocks (e.g., ADC) handle continuous signals.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming PWM or DAC outputs imply internal analog processing; they are digital methods to approximate analog behavior at interfaces.

Final Answer:
Correct