Consider the following statements regarding Memory interfacing in 8051:1.Address decoding is required for memory interfacing.2.Chip select signal is used to enable memory device.3.Multiple devices can share data bus.Which of the above statements is/are correct?

Correct Answer: B - 1, 2 and 3

Quick Concept Explanation

The classic 8051 is an 8-bit Harvard-style microcontroller with separate code and data spaces. The standard core has 4 KB on-chip program ROM and 128 bytes internal RAM, supports external memory, multiple interrupts and configurable interrupt priority. Key relation: Reset SP=07H; classic internal RAM=128 bytes; standard ROM=4 KB.

Exam focus: Remember 07H for stack pointer reset. Common trap: 00H is not the reset value of the 8051 stack pointer.

Statement-wise Verification

• Statement 1 - Correct.
  Address decoding is required for memory interfacing.
  The standard core has 4 KB on-chip program ROM and 128 bytes internal RAM, supports external memory, multiple interrupts and configurable interrupt priority.
• Statement 2 - Correct.
  Chip select signal is used to enable memory device.
  The standard core has 4 KB on-chip program ROM and 128 bytes internal RAM, supports external memory, multiple interrupts and configurable interrupt priority.
• Statement 3 - Correct.
  Multiple devices can share data bus.
  The classic 8051 is an 8-bit Harvard-style microcontroller with separate code and data spaces.

Core Concept

The classic 8051 is an 8-bit Harvard-style microcontroller with separate code and data spaces. The standard core has 4 KB on-chip program ROM and 128 bytes internal RAM, supports external memory, multiple interrupts and configurable interrupt priority. On reset the stack pointer is 07H, so the first PUSH stores at 08H.

Formula / Key Relationship

Reset SP=07H; classic internal RAM=128 bytes; standard ROM=4 KB.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 3. Option C is incorrect because it omits correct statement(s) 2. Option D is incorrect because it omits correct statement(s) 1.

Exam Shortcut / Approach

Remember 07H for stack pointer reset.

Common Mistake

00H is not the reset value of the 8051 stack pointer.

Quick Revision

Address Decoding Chip Select and Shared Data Bus is linked with Memory Interfacing, 8051 Interfacing and Microprocessors and Microcontrollers. Remember 07H for stack pointer reset.