In 8085 name/names of the 16 bit registers is/are______.

Question

Examoogle · Accepted Answer

Both

Explanation: In the Intel 8085 microprocessor, both the Stack Pointer (SP) and the Program Counter (PC) are designated 16-bit registers. These registers are essential for managing the flow of execution and memory addressing during program operation.

Working Principle: The Program Counter holds the 16-bit address of the next instruction to be executed, incrementing automatically after each fetch. The Stack Pointer holds the 16-bit address of the top of the stack in RAM, which is used for temporary storage of return addresses during interrupts and subroutine calls (CALL/RET instructions).

Key Formulas: $Range = 2^{16} = 65,536 	ext{ locations}$ — The addressable memory range provided by a 16-bit register.

Key Points: The 8085 is an 8-bit microprocessor, but it uses 16-bit registers for memory management.; Program Counter (PC) sequences the execution flow.; Stack Pointer (SP) points to the top of the stack area in Memory.; All other general-purpose registers (A, B, C, D, E, H, L) are 8-bit, though they can be paired (e.g., HL) to hold 16-bit values.

Advantages: Enables addressing up to 64 KB of memory.; Simplifies subroutine handling and interrupt processing.

Disadvantages: None, they are architectural necessities for Von Neumann/Harvard hybrid architecture.; 16-bit operations on an 8-bit ALU require multiple clock cycles.

Applications: Instruction fetching; Nested subroutine calls; Interrupt handling stack management

Additional Info: The 8085 Address Bus is also 16-bit wide, matching the capacity of the PC and SP registers.. Option A is correct but incomplete as Option B is also correct; therefore, Option C is the best answer.

Answer: C is correct — Both the Stack Pointer and Program Counter are 16-bit registers used for memory addressing in the 8085 architecture.

Exam Tip: Always remember that while the 8085 is an 8-bit processor (data path), it is a 16-bit address architecture, meaning it can access $2^{16}$ memory locations.

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