8051 Microcontroller Question Related

Discussion in 'Embedded Systems and Microcontrollers' started by vincent19-mas, Dec 21, 2013.

  1. vincent19-mas

    Thread Starter Member

    Dec 27, 2012
    83
    1
    Hey guys, I am revising on the 8051 Microcontroller.

    I face one problem here for this question especially question (c).

    It stated CLR 78H. Does that means that the content of 78H will be cleared and become 00H ?

    Thanks !
     
  2. JohnInTX

    Moderator

    Jun 26, 2012
    2,347
    1,029
    http://www.win.tue.nl/~aeb/comp/8051/set8051.html#51clr

    It clears bit #78h in the bit-addressable segment (in RAM 20h-2Fh) not register 78h. If I read it right, bit 78h is the LSbit of RAM register 2Fh.

    CLR A clears all bits of the accumulator, CLR C clears the carry, CLR (anything else) clears one of the RAM bits. To clear other registers you'd use MOV Rn,#00h
     
    Last edited: Dec 21, 2013
    absf likes this.
  3. nigelwright7557

    Senior Member

    May 10, 2008
    487
    71
    Its a poor question.
    Clearing something to 00h suggests clearing 8 bits.
    Clearing a bit to 0b is something different.
     
  4. Arm_n_Legs

    Active Member

    Mar 7, 2007
    183
    10
    Hi... just curious... may I know what institution is this? Questions are asked in 2 languages?
     
  5. Brian Griffin

    Member

    May 17, 2013
    40
    12
    It is in Malaysia. Some institutions do use two languages in the question papers.:)
     
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