A deep dive into the reverse engineering of a Commodore-designed sync splitter board found in a Commodore 64 housed in a PET case. The board takes composite video output from the VIC chip and splits out horizontal and vertical sync pulses for the monitor. The analysis explains why the board is necessary (the VIC chip combines signals internally), and how Commodore's engineers went beyond a simple passive filter approach by adding one-shots for clean pulse timing and logic gates for blanking. The digital TTL-level video path is also noted as a distinguishing feature from conventional analog sync splitters.
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