Conditional Call

Discussion in 'Programmer's Corner' started by SIVAJANAKIRAMAN, Jul 21, 2012.

  1. SIVAJANAKIRAMAN

    Thread Starter New Member

    Jul 21, 2012
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    Dear All,
    I want to know how conditional Call takes 9T-states when condition fails.
    Exactly what is that 2nd machine cycle. In Nagoorkani book it is given as Memory read. what does it reads?

    thanks in advance.
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    The conditional call is a three(3) byte instruction. The 8085 has an 8-bit data bus. Those three bytes must be read by MEMRD (Memory Read) cycles. Now the condition can be evaluated at ANY point during those three MEMRD cycles. If the condition is FALSE execution continues where the PC (Program Counter) is pointing; at the opcode of the next instruction.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    Welcome to AAC!

    A thread belongs to the OP (original poster). Trying to take over someone elses thread is called hijacking, which is not allowed at All About Circuits. I have therefore given you a thread of your very own.

    This was split from conditional call vs unconditional call
     
  4. JohnInTX

    Moderator

    Jun 26, 2012
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    Just curious for the OP, what are you doing with the 8085? I've written a bunch of 8080/5 code but that was decades ago.. Great part but who is still using it?
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,144
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    Engineering schools in Asia apparently. No problem with it as a learning experience. It worked for me.
     
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