The interfacing of 256 bytes memory using _______address line.

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Examoogle · Accepted Answer

8

Explanation: The number of address lines required for a memory chip is determined by the relationship $2^n = N$, where $n$ is the number of address lines and $N$ is the total number of memory locations in bytes. For a 256-byte memory, $N = 256$, which is equivalent to $2^8$.

Working Principle: The microprocessor identifies each unique memory location using a binary address. Each address line represents one bit of the address bus. By using 8 address lines, the system can generate $2^8 = 256$ unique combinations, ranging from $00000000_2$ to $11111111_2$, which perfectly addresses each of the 256 individual byte locations.

Key Formulas: $N = 2^n$ — where $N$ is memory capacity in bytes and $n$ is the number of address lines.; $n = \log_2(N)$ — formula to calculate required address lines.

Key Points: Memory capacity is always a power of 2 in standard digital architectures.; Each address line acts as a binary selector.; The total addressable memory space increases exponentially with each additional line.

Advantages: Efficient utilization of address bus space.; Predictable memory mapping for firmware design.

Disadvantages: Requires decoding logic if multiple memory chips are used.; Limited capacity per chip compared to higher-density memories.

Applications: Embedded system firmware storage.; Look-up table (LUT) implementations in microcontrollers.

Additional Info: For $1 	ext{ KB} = 1024 	ext{ bytes}$, $n = 10$ lines are required.. Option A (2 lines) covers 4 bytes, Option B (4 lines) covers 16 bytes, and Option D (16 lines) covers 65,536 bytes (64 KB).

Answer: C is correct — Since $2^8 = 256$, a memory capacity of 256 bytes requires exactly 8 address lines to uniquely identify every byte.

Exam Tip: Always remember the powers of 2 (2, 4, 8, 16, 32, 64, 128, 256, 512, 1024) to quickly solve addressing problems without calculation.

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