Mark Snesrud and Bob Mayo explained how they solved the first Adobe semaphore puzzle twenty years ago. Near as I can make out from their paper, they assumed that it wasn’t the semaphore positions that were the code, but the changes from one position to the next. Each semaphore has four possible positions (at the time, anyway), but there are/were seventeen possibilities for each change for each semaphore – the semaphore can turn clockwise or counterclockwise, 45 degrees, or 90 degrees, or 135 degrees, etc. Like the Adobe website says, there are 256 possible semaphore displays, but if it’s the changes that carry the code, then each change has 17-to-the-fourth possibilities. But seems like Mayo and Snesrud immediately decided it was the changes that carried the code. How did they do that?
Simpler question: how long did the semaphore take to display the whole Pynchon novel?