Bugs & Glitches of High-Level NES Tetris

Why does NES Tetris start to break if you play for too long? It's all explained right here.
LINKS
INLINE LINKS
HydrantDude: @hydrantdude3642
CHAPTERS
00:00 Intro
00:57 Falling Speed Limit
04:12 Level Number Display
07:40 Glitched Color Palettes
17:06 NES Code Structure
22:54 Jump Table
29:07 Game Crashes
40:08 Limited Tile Confetti
46:58 Infinite Tile Confetti
51:29 Outro

[hydrantdude]

Wonderfully explained! This channel was a source of inspiration for my own videos on mechanics, so it coming back around and contributing to one of the videos is an incredibly cool feeling. Even though I already know how everything described worked, I still got some great value out of the visuals in this video. Writing out all the code in the frame at 37:00 is beautiful. Most of all though, I want to give Frieze credit for seemingly deriving lots of the info on his own-- our community has already disassembled the game fully, but when he reached out to me with the script, he'd disassembled the code himself with different labels! I barely had anything to correct him on, which was refreshing compared to a lot of other journalism following the publicity of Blue Scuti crashing the game.
Thanks for the excellent work!

[GamingGardevoir]

The smile that came across my face when you said “…and viewers like you! Thank You!” is immeasurable. That was a heavy nostalgia bomb for me!!! 😊

[zeta]

When we talk about the vblank interrupt on the NES pausing the CPU no matter what it's doing, that's more true than you might think. The PPU signals vblank using NMI, which stands for "non-maskable interrupt", and it's a special signal the CPU is hard-coded to always take. Other interrupts (IRQs) can be ignored by the software during sensitive work. If you're reading the NESDev Wiki or doing research, you'll often hear people talk about their "NMI routine." It's the same thing, that's just the work that starts at the top of vblank. Naming things is hard. :D

[EntergeticalakaBot]

The waiting spinning loop feels like a Sisyphus moment, just doing the same thing over and over until its out of its misery

[aprilgw]

This video reignites the spark of wonder I get from low-level programming. Things are what we make of them. The numbers aren't "signed integers" unless we treat them like one. It's all just ones and zeroes. Excellent explanation as always ❤

[Zettymaster]

i love how this is essentially explaining bugs (mostly use after free, aliasing and out of bounds indexing) in context. still technical, but with enough game elements and diagrams to explain everything.

[JJW]

Found this channel last night and I'm endlessly impressed. Fantastic communicative visuals, great voice over, no distracting music -- 10/10, love it.

[PubstarHero]

Why did you upload this? I have chores I wanted to handle, but now I have to watch an hour long video about the tetris kill screen and glitches.

[LeeBrian]

“And viewers like you, thank you.” I really like that quote since it brought me PBS and PBS kids nostagia!

[WindowsFan]

Level display sequences:
0 - 29: Normal, pretty obvious.
30 - 49: Tens in hexadecimal (00, 0A, 14, ⋯, BE)
50 - 89: Even -> x6 (starting from C), Odd -> 20 + n (which n increases when the even counter goes to 06)
90 - 255: The RANDOM Squad

[biggallcaps]

Thanks for covering this! With the Tetris records being broken, now I can finally have an idea as to why it does what it does

[brianalmon]

Going beyond the expected address space is like going off the edge of a medieval map - here there be dragons.

[WingedAsarath]

I see those choices of the numbers 69 and 420 in your example at 22:39 🧐

[evidence]

I was busy but not anymore, RGME video!!

[RoysGamingGarret]

There is one thing that is missed. One of the levels between 210 and 220 is around 800+ lines before it proceeds to level up.

[Grey-mopy]

I always love when you post a new video, especially these super long ones. it's so intriguing to learn about how all these older games and systems worked with their limited capabilities.
amazing video as always, time to rewatch over and over until I memorize it :)

[thstellation]

The duplicated inhale at 27:19 is definitely one of my favorite parts of the video

[Pidgeonz]

I dont understand 90% of this stuff, but i cant stop watching these videos on here. Its always nice background noise as well while i play video games 😅 Very fascinating stuffs

[spartonberry]

22:46 The sequel, Tetris 2+BomBliss for the Famicom has a major bug where if the player 2 Start Button is pressed to pause the game, the game will still pause and hide the screen as expected, but will set a flag incorrectly so that when the game is resumed, the game will try to restore the screen data from the wrong area preserved in the cartridge RAM. This probably went undetected because the game was only released on the Famicom and during the time when the OG Famicom (with a P2 controller lacking the Start and Select buttons) was on the market.
The bugged code will try to restore the P1 and P2 playfields respectively with the P2 playfield data and correspond later data in RAM.

[erok]

Summoning Salt just put out a new video on NES Tetris, and I already knew some of the stuff he was going to mention like the glitch colors because of this video