Metroid II Fast Fall Explanation

There is a glitch in metroid II where if you catch a corner as you're falling you will fall faster: http://www.metroid2002.com/2/speed_tricks_corner_fastfall.php

The exact details of how that worked were not well known by runners.

Look at this picture of Samus falling http://imgur.com/dDYlGF0

Lets say Samus is 1 unit above the ground and is above the very left most unit of the ground. idk if that's true, but I don't exactly know values.

Now if you were to press no inputs from this position, these would be the following frames: http://imgur.com/7KboWWG for two frames and then http://imgur.com/NBIgv3Z

Now if you pressed left for one frame instead... http://imgur.com/6sFo7wg for two frames and then http://imgur.com/duDswsI

That one frame of left made a huge difference and caused fast fall.

What I think happens is that at that one unit above the ground when Samus is falling, the game determines that Samus should land soon. If you move to the unit to left of the block at the very last frame possible, the game gets confused because Samus "Landed" but is in the air still. Thus it pushes her downwards causing fast fall. This is also why fast fall causes you to lose a lot of forward momentum and cancels spin jump is because the game thought you landed.