8085 microprocessor miscellaneous

8085 microprocessor miscellaneous

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8085 Microprocessor

8085 microprocessor miscellaneous
  1. The contents (in Hexadecimal) of some of the memory locations in an 8085A based system are given below:

    The contents of stack pointer (SP), program counter (PC) and (H, L) are 2700H, 2100H and 0000H respectively. When the following sequence of instructions are executed
    2100 H:      DAD SP
    2101 H:      PCHL
    the contents of (SP) and (PC) at the end of execution will be








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    Given
    (SP) = 2700H
    (PC) = 2100H
    (HL) = 0000H
    2100H : DAD SP: it adds the contents of stack pointer (SP) to the content of HL pair and store the result in HL pair.
    ∴ 2700H + 0000H = 2700H stored in HL pair 2101H: PCH L; the content of HL pair are transfered to program counter.
    So now PC has 2700H and contents of SP remains unchanged
    ∴ (PC) = 2700H
    (SP) = 2700H

    Correct Option: B

    Given
    (SP) = 2700H
    (PC) = 2100H
    (HL) = 0000H
    2100H : DAD SP: it adds the contents of stack pointer (SP) to the content of HL pair and store the result in HL pair.
    ∴ 2700H + 0000H = 2700H stored in HL pair 2101H: PCH L; the content of HL pair are transfered to program counter.
    So now PC has 2700H and contents of SP remains unchanged
    ∴ (PC) = 2700H
    (SP) = 2700H

  1. A software delay subroutine is written as given below:

    How many times DCR L instruction will be executed?








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    DCRL will be executed 255 times till it content of L becomes zero.
    Then, for every decrement of content of H, DCRL will again be executed by 256 times. (When L is decremented by 1 and becomes FFH). This will be repeated by 254 times.
    Hence, no. of execution of DCRL = 254 × 256 + 255 = 65279

    Correct Option: A

    DCRL will be executed 255 times till it content of L becomes zero.
    Then, for every decrement of content of H, DCRL will again be executed by 256 times. (When L is decremented by 1 and becomes FFH). This will be repeated by 254 times.
    Hence, no. of execution of DCRL = 254 × 256 + 255 = 65279

  1. After completing the execution, microprocessor return to








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    NA

    Correct Option: B

    NA

  1. Which of the following actions detect locations, and remove mistakes from a programme routine?








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    NA

    Correct Option: B

    NA

  1. Direct– Memory Access Channel (DMA) facilitates data to move into and out of the system








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    NA

    Correct Option: B

    NA