SMW World Record Explained Additional Notes

Note 1 (1:49): There are 74 total levels: Bowser's Castle is technically two separate levels, Front Door and Back Door, both of which have no exits because they lead straight to the ending. There's also Yoshi's House and the Top Secret Area, both which have no exit.

Note 2 (1:57): Other popular categories include 11 Exit Glitchless, All Castles, No Cape No Starworld and Lunar Dragon. Check speedrun.com/smw for the full list.

Note 3 (2:15): The full definition of 11 Exit is a bit more involved. According to the rules on speedrun.com, the definition is any% no credits warp and no letting the instruction pointer hit anywhere but ROM, open bus, and the intended RAM area ($7F8000-$7F8182), and no modifying the intended RAM area. The reason the definition is so oddly specific is because the cloud glitch manipulation technically constitutes arbitrary code execution (ACE), by most definitions. It was grandfathered in by carefully writing the rules around it, mostly because its intent is solely to keep the game from crashing, and, to put it simply, because it just makes the run better.

Note 4 (3:54): For further reading, this excellent document by SethBling is a very useful piece of information. https://docs.google.com/document/d/1P9I_IlBFPesOJ16StLaUxyMYkRspPMCr-8mexGj-NIw
Also, this document details why emulated rereleases handle open bus differently, making this glitch SNES exclusive. https://docs.google.com/document/d/1my6JXPM0iHERHjsptm6453rDGIJENqTVJnK7UGuQlLo

Note 5 (4:51): It's actually a bit that states if the code for collecting a powerup should be run, so it's also set for coins that run the code to make a sparkle effect, even though they're not actual powerups. It's only incorrectly set for all Chuck enemies (except that one with a shovel in Valley of Bowser), an invisible block found in Switch Palaces, and a sprite used to make rooms dark. Item swap is technically possible on all of them but the dark room sprite can't be swallowed and give a powerup.

Note 6 (5:10): Another variable can also throw things off. There's a multi-purpose timer that's used in various ways by different kinds of sprites. Powerups use it while they are rising out of a block. While the timer is above 24, the powerup can't be collected yet, which also blocks Yoshi from getting anything when swallowing it. This was done to prevent grabbing powerups by clipping into the corner of a block from under it, like it can be done in SMB1. The Chargin' Chuck uses that  same timer to control its behaviour. Its value can sometimes exceed 24, in which case nothing happens when the Chargin' Chuck is swallowed.

Note 7 (5:14): The way the game finds the item box ID and the pointer to the powerup subroutine is actually much more convoluted and depends on Mario's powerup state. This is a gross simplification to boil it down to the simplest concepts. Check out Retro Game Mechanics Explained's video on the Cloud glitch to get all the juicy details.

Note 8 (5:32): The item reserve box stores its possible powerups with its own ID system where $00 is an empty box and $01-$05 are the powerups. The powerups' sprite IDs are $74-$78, so to associate the item reserve box ID to the correct sprite ID, an offset of $73 is added. All the values displayed already include that offset for simplicity. In reality, the garbage data the game reads is $14, but after adding the offset, the resulting sprite ID is $87, which is Lakitu's cloud.

Note 9 (6:15): This also creates mirroring, where a given value can be read at multiple different addresses. Because one or more bits in the address isn't connected, their value doesn't matter. The address in question is more specifically at $014A13. More info in Part 9 and 9b of Retro Game Mechanics Explained's series about the SNES system features:
https://youtu.be/-U76YvWdnZM
https://youtu.be/PvfhANgLrm4

Note 10 (11:15): Tsuake also avoids the tape at the end of each stage. Hitting the tape gives bonus stars, but since they count down at the same time as the timer, it doesn't take any additional time other than a negligible chance it could introduce lag. However, you go into a bonus stage when you hit 100 bonus stars, so while it doesn't matter in 11 Exit, it comes into play in longer categories. There's no meaningful situation where hitting the tape is ever a good thing, so runners get into the habit of avoiding it all the time.

Note 11 (16:09): Running has an acceleration of 24 subspeed/frame². Subspeed is a subdivision of speed in 16 increments to allow for smoother acceleration, the same way subpixels allow for smoother movement. At 24 subspeed/frame², Mario's speed alternates between going up by 1 and by 2 subpixels/frame.
	When the cap of 48 is reached, his speed goes down by 1 per frame until it's below 47. This is what causes the pattern we see. Consider subspeed values in the upper half (H) or lower half (L). If at 47 speed, the subspeed value is high (H), Mario will have 49L speed on the next frame, otherwise he will have 48H. So, you get 47L, 48H, 47H, 49L, 48L, 47L and the cycle repeats.
	Now, when Mario is flying, the acceleration is a 64 subspeed/frame², or a flat 4 subpixels/frame². Regardless of the subspeed value, the cycle will therefore always be 47, 51, 50, 49, 48, 47 and so on.

Note 12 (17:18): Assuming normal presses (it's possible to do two 1-frame taps to speed up the cape pumping animation), you can press left every 55 frames - 0.916 seconds - at minimum.

Note 13 (20:03): There are many other setups that could work, but this is the one that's generally deemed the easiest because it has three consecutive frames where it works. Other possibilities include holding down for one frame after 5 frames, or holding down for 3 frames after 11 frames, but those are frame perfect. Also, different setups makes Mario clip at different points in the stairs. Where Mario clips on the stairs has little impact on speed and difficulty.

Note 14 (22:05): The sprite is specifically used for the bouncing animation. The spinning block is an animated background tile - just like ? blocks - but its timer is controlled by the bouncing block sprite, which is why that sprite is kept loaded (but invisible) for as long as the block spins.

Note 15 (23:43): Although the sum of digits can be used as a pretty accurate shorthand, it's not a pure direct correlation. The routine that displays the score generally takes more cycles for higher numbers, but some numbers are more efficient than others for different reasons. You can find more information on this article by IsoFrieze: https://smwspeedruns.com/Score_Manipulation

Note 16 (24:20): I ran a test by playing the same inputs (adjusted for lag) with the score manually frozen at 99900 and 100000, and the run on 99900 score had 63 more lag frames (+1.05 seconds). Of course, it's impossible to have 100000 score for the entirety of the run - you're bound to have higher numbers as you go through the first levels - but I also found that Donut Plains levels tend to have lower lag naturally, with Donut Secret 1 and Donut Secret House both having no more lag at 99900 compared to 100000. Therefore, ending DSH with a score just below 100000 to set up for the rest of the run is not a problem.

Note 17 (24:40): Lag is a very complex matter and depends on many different factors. I ran a test with 99900 points and 100000 points in otherwise identical conditions and the difference was 6 frames, but I didn't replicate Tsuake's game state exactly. It's impossible to tell with perfect precision and accuracy how much time is lost to lag in any given situation.

Note 18 (28:29): Fireballs appear once every 32 frames based on a global timer, and he spent about 5 frames where he could have been hit by one. There are 8 possible positions, making it a 5/256 chance, or roughly 2%. He lost 0.9 seconds: 0.15 seconds from not canceling the fireballs instantly, and 0.75 seconds during which the game is frozen by the power down animation.

Note 19 (32:35): I made this TAS to the best of my limited ability, but I had no prior experience with SMW TASing. I actually used Bruno Visnadi's inputs from his 11 exit TAS (no cloud) for three sections: stairs clip, the first half of the second room in DSH (until right after the boo ring) and the first half of Bowser's Castle room 5. I know for a fact lag isn't optimal (I got too many coins) and Bruno Visnadi's TAS uses more advanced strategies in a few levels that I didn't have the patience to do nor the heart to rip off (aside from the three instances I mentioned). See Bruno Visnadi's 11 exit TAS: https://www.youtube.com/watch?v=OMNsL7deKlk