Hideout Helm Medals Bug Explained (US)

HIDEOUT HELM MEDAL BUG (US) EXPLANATION
On the US Version of DK64, under certain conditions, you will be unable to collect the medals in Hideout Helm. For many, this left 101% an impossible accomplishment without use of glitches. It should be noted that this was fixed on the PAL and Japanese releases of DK64.

Turns out that if you forget a Helm Medal during a 101% run, it is possible to save your run without having to revert to spawn snagging ( https://www.youtube.com/watch?v=-aFEiTGhClw ) or any other TAS related tricks. When you shut down a section of the Blast-O-Matic, a temporary flag is set in memory:

    {byte = 0xB9, bit = 3, flagName = "Helm: DK Room Shut Down"},
    {byte = 0xB9, bit = 4, flagName = "Helm: Chunky Room Shut Down"},
    {byte = 0xB9, bit = 5, flagName = "Helm: Tiny Room Shut Down"},
    {byte = 0xB9, bit = 6, flagName = "Helm: Lanky Room Shut Down"},
    {byte = 0xB9, bit = 7, flagName = "Helm: Diddy Room Shut Down"},

Like flags, temporary flags dictate completion of certain elements of Donkey Kong 64. This includes watching various cutscenes (Long Boss intros), completing certain tasks (Lanky Maze Barrel in Helm, Arcade rounds), and various environmental changes (Opening the roman numeral doors in Helm). However, unlike permanent flags, which are stored on your save file forever until you delete it, temporary flags are cleared upon resetting the console. This fact is often covered up from a player completing a related task which sets a permanent flag (Acquiring a boss key preventing need to watch that boss intro again, shutting down the blast-o-matic preventing need to play Lanky's Maze Game or open the roman numeral doors in Helm, acquisition of the Arcade R1 Golden Banana preventing need to replay the first round of DK Arcade).

However, as hinted before, this caused problems when it came to the Helm Medals.

These temporary flags dictate the state of whether the Helm medals will be deemed "collectable" or "uncollectable" when the room is loaded (when the spawn snag check is made). These flags remain set until you reset/power down the console. When you boot up the save file again, like with the state of the long boss cutscenes being watched, these will be reset to their "unset" state. This means that when you re-enter helm for a second time, as long as you fit the following conditions (or are on PAL/JP) you will be able to recollect the medals:
- You have not reset/powered down the console after turning off the blast-o-matic
- You have turned off all sections of Helm prior to turning off the Blast-o-Matic (aka, you haven't skipped any rooms before going to Diddy's room to turn it off)

If this is not the case, the temporary flags will be in their unset state and there will not be a way to set them again (and therefore make the medals collectable again glitchless) since the Helm Minigame barrels disappear upon turning off the Blast-O-Matic.

Instead of the check being related to the temporary flags (Like the US version), the PAL/JP releases perform the check based on the state of the Blast-o-Matic permanent flag (Byte: 0x60,Bit: 2) or the temporary flags (if either are set, then the medals will become collectable), and therefore solves the bug from ever occurring.