Friday, May 28, 2010

uPD1771C noise puzzle



LFSR feeding a delta-modulated logarithmic DAC???
Evil 80's reverse engineering protection???
Alien message?

3 comments:

  1. It looks like rising exponentials on the positive side, decaying exponentials on the negative side. Not that hard to create with digital logic, though probably time consuming to exactly recreate.

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  2. Hi

    Sure, but the precise steps heights and the distance between gap 'resets' is controlled by two or more clocks. This chip really needs decapping.

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  3. I took a crack at it. I think one clock can certainly get you something similar.
    http://8bc.org/forums/viewtopic.php?pid=327085#p327085

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