What is the primary characteristic of Binary Coded Decimal (BCD)…
2025
What is the primary characteristic of Binary Coded Decimal (BCD) representation in digital systems?
- A.
It uses a single binary number to represent the entire decimal number.
- B.
It represents each decimal digit separately using a fixed 4-bit binary code.
- C.
It converts binary numbers into Gray code for error detection.
- D.
It encodes every decimal digit using its hexadecimal equivalent.
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Correct answer: B
The primary characteristic of Binary Coded Decimal (BCD) is that each individual decimal digit (0 through 9) is represented by its own fixed 4-bit binary code.
Unlike standard binary conversion—which translates an entire number into a continuous binary sequence—BCD preserves the structural layout of the decimal system.
Key Characteristics:
Direct 4-Bit Mapping: For example, the decimal number
35is not converted as a whole (35 = 1000112). Instead, each digit is converted separately:3becomes0011and5becomes0101, resulting in the BCD representation0011 0101.Invalid States: Since 4 bits can represent 16 unique combinations (0000 through 1111) but decimal only uses 10 digits (0 through 9), the remaining 6 binary combinations (1010 through 1111, or 10 to 15 in decimal) are considered invalid or illegal states in BCD.
Use Case: BCD is primarily used in systems where numeric values need to be frequently displayed to humans on digital screens (like digital clocks, calculators, and electronic voltmeters) because it eliminates the complex mathematical overhead of converting large binary strings back into decimal digits for display.