Talk:APU Frame Counter: Difference between revisions
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(Created page with 'The frame counter [http://uxul.org/~noname/chips/cpu-2/no-metal/stitched/final/ on the die] seems to be a 15-bit linear feedback shift register (with taps at the 14th and 15th bi…') |
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The frame counter [http://uxul.org/~noname/chips/cpu-2/no-metal/stitched/final/ on the die] seems to be a 15-bit linear feedback shift register (with taps at the 14th and 15th bits); when the LFSR is initialized with all 1s and clocked every other CPU cycle, a decoder appears to generate signals at 7456, 14912 (+7456), 22370 (+7458), 29828 (+7458), and 37280 (+7452) cycles. I have not yet determined how these relate to the 2 different sequence modes. --[[User:Quietust|Quietust]] 17:09, 23 January 2011 (UTC) | The frame counter [http://uxul.org/~noname/chips/cpu-2/no-metal/stitched/final/ on the die] (upper-right, just below the joypad strobe pin) seems to be a 15-bit linear feedback shift register (with taps at the 14th and 15th bits); when the LFSR is initialized with all 1s and clocked every other CPU cycle, a decoder appears to generate signals at 7456, 14912 (+7456), 22370 (+7458), 29828 (+7458), and 37280 (+7452) cycles. I have not yet determined how these relate to the 2 different sequence modes. --[[User:Quietust|Quietust]] 17:09, 23 January 2011 (UTC) | ||
Revision as of 17:10, 23 January 2011
The frame counter on the die (upper-right, just below the joypad strobe pin) seems to be a 15-bit linear feedback shift register (with taps at the 14th and 15th bits); when the LFSR is initialized with all 1s and clocked every other CPU cycle, a decoder appears to generate signals at 7456, 14912 (+7456), 22370 (+7458), 29828 (+7458), and 37280 (+7452) cycles. I have not yet determined how these relate to the 2 different sequence modes. --Quietust 17:09, 23 January 2011 (UTC)
