This question was asked inGPSC Deputy Executive Engineer (Electrical) Class-2 Master Paper 2026Question 133 of 195 published · Gujarat Public Service CommissionOpen paper
Q133Easy8051 Microcontroller

8051 સૂચનાઓ (instructions) અંગે નીચેનાં વિધાનો ધ્યાનમાં લો:
1. MOV સૂચના રજિસ્ટરો/મેમરી વચ્ચે ડેટા ખસેડે છે.
2. ADD સૂચના ફ્લેગ્સને અસર કરે છે.
3. INC સૂચના કેરી ફ્લેગને અસર કરે છે.
ઉપરોક્તમાંથી કયું/કયાં વિધાન સાચું/સાચાં છે?

જવાબ અને પગલાવાર ઉકેલ
સાચો જવાબ: C. ફક્ત 1 અને 2
ટૂંકી સમજૂતી

C — ફક્ત 1 અને 2. MOV ડેટા ખસેડે છે અને ADD CY, AC, OV અને P ફ્લેગને અસર કરે છે. 8051માં INC કેરી ફ્લેગ (CY)ને અસર કરતું નથી.

વિગતવાર ઉકેલ (મૂળ ભાષામાં)

Statement-wise Verification

  • Statement 1 - Correct.
    MOV instruction transfers data between registers/memory.
    The classic 8051 is an 8-bit Harvard-style microcontroller with separate code and data spaces.
  • Statement 2 - Correct.
    ADD instruction affects flags.
    Remember 07H for stack pointer reset.
  • Statement 3 - Incorrect.
    INC instruction affects carry flag.
    8051 INC does not affect the carry flag

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) 2. Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option D is incorrect because it includes incorrect statement(s) 3.

Exam Shortcut / Approach

Remember 07H for stack pointer reset.

Common Mistake

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

Quick Revision

MOV ADD and INC Flag Effects is linked with Instruction Set, 8051 Microcontroller and Microprocessors and Microcontrollers. Remember 07H for stack pointer reset.

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