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Another little update

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  • korgpolyex800
    Gooday Poly fans, I managed to spend another few hours pouring over the EX800 assembler code and discovered a fundamental error in my interpretation of one
    Message 1 of 7 , Jul 2, 2007
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      Gooday Poly fans,

      I managed to spend another few hours pouring over the EX800 assembler
      code and discovered a fundamental error in my interpretation of one
      variable. That single mistake had then led me to make multiple errors
      in the interpretation of other parts of the code which then led on to
      further errors and so on.

      While decoding the MIDI code that carries out a program change, I
      incorrectly interpreted a check against a variable as being the
      program change enable disable flag (parameter 87). But it turns out
      that the variable was in fact the flag that determines whether the
      EX800 display is in program or parameter set mode. The ramifications
      of that little mistake spilled into my interpretation of a great deal
      of the code that handles all of the keypad and buttons and display of
      information etc.

      So after correcting that mistake, I've been able to make a great deal
      of progress interpreting the keypad, buttons and display code.

      Also, I've been looking at the multiplexing part of the code where the
      various sound control chips are controlled. I've slowly been picking
      away at it and it's been tough going because this part of the software
      has the least connection to external inputs (such as the MIDI or
      keyboard input). To put it another way, the code is very mathematical
      in nature using many memory variables the use of which is still
      unknown. For example, one part of the multiplexing code is set up just
      to provide a toggling mechanism that allows the display to flash two
      horizontal bars when doing a patch copy. Who would have thought that
      inside of all of the EG's and VCF controls etc there would be a little
      section of code just set up for flashing those silly horizontal bars
      when doing a patch copy. And another section of the code handles
      recalculating the VCF cutoff according to the trigger parameter (para
      46) after a new key is hit.

      The most interesting question on my mind right at the moment is: What
      is the mathematics used to operate the EG's? If I can get a good
      answer to that question soon then I am hoping to be able to answer the
      next really important question which is: Does the CPU have enough
      spare cycles left to operate a fourth EG? Because if it does have
      enough CPU cycles left for that then we'll be able to use that fourth
      EG to control maybe noise level, resonance, or even MG depth. And that
      would be a great new feature.

      I wish I had more to report but that's about it for now. This email is
      more of a note to let you know that I am still plugging away at this
      dang thing.

      Mike H.
    • David Mochen
      You are a genius, Mike. Hope I will be able to get your kit once it is made available. Best regards from Argentina, Dave ... From: korgpolyex800 To:
      Message 2 of 7 , Jul 2, 2007
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        You are a genius, Mike. Hope I will be able to get your kit once it is made available.
        Best regards from Argentina,
         
        Dave
        ----- Original Message -----
        Sent: Monday, July 02, 2007 11:27 AM
        Subject: [korgpolyex] Another little update

        Gooday Poly fans,

        I managed to spend another few hours pouring over the EX800 assembler
        code and discovered a fundamental error in my interpretation of one
        variable. That single mistake had then led me to make multiple errors
        in the interpretation of other parts of the code which then led on to
        further errors and so on.

        While decoding the MIDI code that carries out a program change, I
        incorrectly interpreted a check against a variable as being the
        program change enable disable flag (parameter 87). But it turns out
        that the variable was in fact the flag that determines whether the
        EX800 display is in program or parameter set mode. The ramifications
        of that little mistake spilled into my interpretation of a great deal
        of the code that handles all of the keypad and buttons and display of
        information etc.

        So after correcting that mistake, I've been able to make a great deal
        of progress interpreting the keypad, buttons and display code.

        Also, I've been looking at the multiplexing part of the code where the
        various sound control chips are controlled. I've slowly been picking
        away at it and it's been tough going because this part of the software
        has the least connection to external inputs (such as the MIDI or
        keyboard input). To put it another way, the code is very mathematical
        in nature using many memory variables the use of which is still
        unknown. For example, one part of the multiplexing code is set up just
        to provide a toggling mechanism that allows the display to flash two
        horizontal bars when doing a patch copy. Who would have thought that
        inside of all of the EG's and VCF controls etc there would be a little
        section of code just set up for flashing those silly horizontal bars
        when doing a patch copy. And another section of the code handles
        recalculating the VCF cutoff according to the trigger parameter (para
        46) after a new key is hit.

        The most interesting question on my mind right at the moment is: What
        is the mathematics used to operate the EG's? If I can get a good
        answer to that question soon then I am hoping to be able to answer the
        next really important question which is: Does the CPU have enough
        spare cycles left to operate a fourth EG? Because if it does have
        enough CPU cycles left for that then we'll be able to use that fourth
        EG to control maybe noise level, resonance, or even MG depth. And that
        would be a great new feature.

        I wish I had more to report but that's about it for now. This email is
        more of a note to let you know that I am still plugging away at this
        dang thing.

        Mike H.

      • jure zitnik
        i m really happy everytime you post about progress, you the man! i wish i could help you but i don t think i m competent to act smart about EG maths ... still
        Message 3 of 7 , Jul 2, 2007
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          i'm really happy everytime you post about progress, you the man! i wish i could help you but i don't think i'm competent to act smart about EG maths :D
          still - i guess if the envelope's slopes are linear then there's not much science. and i think the original envelopes ARE linear. otherwise, you could calculate the (fixed) slope with a simple square function or, if you have enough memory, make a lookup table that'd save the cpu cycles.

          keep it up, we believe in you!
          jure

          On 7/2/07, David Mochen <davidmochen@...> wrote:

          You are a genius, Mike. Hope I will be able to get your kit once it is made available.
          Best regards from Argentina,
           
          Dave
          ----- Original Message -----
          Sent: Monday, July 02, 2007 11:27 AM
          Subject: [korgpolyex] Another little update

          Gooday Poly fans,

          I managed to spend another few hours pouring over the EX800 assembler
          code and discovered a fundamental error in my interpretation of one
          variable. That single mistake had then led me to make multiple errors
          in the interpretation of other parts of the code which then led on to
          further errors and so on.

          While decoding the MIDI code that carries out a program change, I
          incorrectly interpreted a check against a variable as being the
          program change enable disable flag (parameter 87). But it turns out
          that the variable was in fact the flag that determines whether the
          EX800 display is in program or parameter set mode. The ramifications
          of that little mistake spilled into my interpretation of a great deal
          of the code that handles all of the keypad and buttons and display of
          information etc.

          So after correcting that mistake, I've been able to make a great deal
          of progress interpreting the keypad, buttons and display code.

          Also, I've been looking at the multiplexing part of the code where the
          various sound control chips are controlled. I've slowly been picking
          away at it and it's been tough going because this part of the software
          has the least connection to external inputs (such as the MIDI or
          keyboard input). To put it another way, the code is very mathematical
          in nature using many memory variables the use of which is still
          unknown. For example, one part of the multiplexing code is set up just
          to provide a toggling mechanism that allows the display to flash two
          horizontal bars when doing a patch copy. Who would have thought that
          inside of all of the EG's and VCF controls etc there would be a little
          section of code just set up for flashing those silly horizontal bars
          when doing a patch copy. And another section of the code handles
          recalculating the VCF cutoff according to the trigger parameter (para
          46) after a new key is hit.

          The most interesting question on my mind right at the moment is: What
          is the mathematics used to operate the EG's? If I can get a good
          answer to that question soon then I am hoping to be able to answer the
          next really important question which is: Does the CPU have enough
          spare cycles left to operate a fourth EG? Because if it does have
          enough CPU cycles left for that then we'll be able to use that fourth
          EG to control maybe noise level, resonance, or even MG depth. And that
          would be a great new feature.

          I wish I had more to report but that's about it for now. This email is
          more of a note to let you know that I am still plugging away at this
          dang thing.

          Mike H.


        • Russ
          keep up the good work! ... Luggage? GPS? Comic books? Check out fitting gifts for grads at Yahoo! Search.
          Message 4 of 7 , Jul 3, 2007
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            keep up the good work!


            Luggage? GPS? Comic books?
            Check out fitting gifts for grads at Yahoo! Search.
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