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Sunday, June 5, 2011

Timing Diagram for LDA and STA instruction.

Timing Diagram for LDA and STA instruction.

33 comments:

  1. Replies
    1. The columns T1 T2 .... T13 are cycles....

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    2. The clock is in the wall of our house :p Kidding :D

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  2. in lda there will be opcode fetch memory read memory read and again memory? please clarify me.

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    1. LDA is a 16 bit loading instruction.
      Whereas each memory address stores only 8 bit of data
      So to get 16 bit of data memory has to be read twice.

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    2. I think this is wrong. Its the 16bit addres which takes 2 read n one 8bit data in that address that takes 1 read cycles

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    3. YES,DATA IS 8 BIT ONLY BUT TO GET THE MEMORY LOCATION WHERE DATA IS STORED WE REQUIRE TWO READ MACHINE CYCLES.

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    4. This comment has been removed by the author.

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  3. Replies
    1. The lower address of 01H will be replaced by 50H and higher address by 20H....

      Point to remember: Program and Data Memory are two different things...
      If program is there at 2050H Data cannot be stored there...
      This is based on assumption that you are talking about clash of memory (as 2050 we are fetching opcode in this diagram)

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  4. In lda why we didn't use ta memory read in the 2nd and 3rd machine cycle.........bcoz I m confused ......... In the case of lda we write from memory to accumulator..........

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  5. Draw the timing diagram for CALL 2500H and Calculate execution time with T-state and Machine
    cycle. Assume clock frequency 3MHz..... answer ???

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  6. that last one is WB or it should be WR(bar). and in LDA we don't need that last step. right?

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    1. It is WR(bar) you can see once you zoom. No in LDA last step is not required. It is required in STA.

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  7. In LDA what it does in last memory read operation ?

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    Replies
    1. In last memory read operation it takes in the DATA into the accumnulator.

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  8. Sir will the above timing diagram be same for LDA F050H

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  9. for the LDA instruction i need to load/store contents to the accumulator how can we achieve it by using a read cycle at the last as the address is that of the operand.

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  10. Time diagram of sta and lda are basically same???

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    Replies
    1. There is only one difference
      In STA the data is written hence WR(bar) is set to low.
      In LDA the WR(bar) will remain high and the RD will be set to high indicating that the data has been read.

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  11. what is the timing diagram of this instruction 67AD: LDA 9E94h

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