Get to 8-1 without playing worlds 1 through 7 in Super Mario Bros.

[@IsoFrieze]

I forgot to mention, but the $A5 is the signature that Super Mario Bros. uses to determine if that last chunk of memory should be erased or not. By setting it at the beginning (Tennis doesn't change it), the game won't erase the value from Tennis when booted up the second time.

[@GTAce99]

In case anyone asks the potential for this trick in speedruns, it won't change anything. There's already a speedrun category known as "Minus World Ending" where you play on the FDS version of Super Mario Bros., which has a beatable minus world (World 36). Since that's beating a castle on a world value greater than 7, it does the same thing as this trick and unlocks the world select. It can be argued that this is "true Any%", but it is its own separate category. Plus, swapping games would obviously be banned for normal speedruns. Anyway, I've always known about Tennis allowing access to the glitched worlds beyond World 8 but never knew exactly how it worked. Always seemed like one of those "urban legend" type deals even though I knew it was possible since there was video proof online. It's cool to finally see exactly what causes it happen after all these years, so thank you for answering this question I've wondered about forever.

[@evilsdouble]

Tl, DR: Great video, great comment

[@powerkirbybomber6503]

It should be noted that Japanese gamers have known about the Tennis + Super Mario Bros glitch since 1986 (maybe earlier), but it's still really cool to see someone in the west finally cover this glitch.

[@LeftyPem]

This is because the Famicom and NES reset circuits work differently. This is known as “frying” and has been demonstrated on other systems such as Genesis going back to the early 90s. Was even described in a Secrets of the Game book by Rusel DeMaria.

[@nanika2566]

ohh nice to see how it works, was wondering what causes that to happen. I knew about the 'hold some button and press Start' "trick" but didn't know why and how the value of the world it sends you to gets changed by that other game and btw, you likely don't know me at all, but I remember you being a mod on some smw forum and I'm amazed by how far you got after all these years TwT

[@stevenschiro1838]

Enjoy all of your stuff, thanks for the video!

[@ronichoudhury]

Great demo and explanation!

[@WhiteDragon103]

I wonder if this would qualify as a real speedrun strat given it is possible on real hardware.

[@IsoFrieze]

It could definitely be a speedrun, but it definitely wouldn't replace the existing any% run. It'd be its own thing.

[@duccie]

couldn't you just increment that byte to 7(?) and instantly go to world 8?

[@IsoFrieze]

Yes you could. At the time of making this video I was curious about the quickest way to get the "game clear condition" (setting hard mode), which would be through level K-1. You can also set the value to 32 (hex $20) to go straight to X-1. X-1 is just 8-4 but the pipes and loop points are broken, so you can just run to the end of the level from the first room.

[@MrCheeze]

Why did you unlock world select, instead of just going to world 8 directly?

[@IsoFrieze]

Copied from another reply: "Yes you could. At the time of making this video I was curious about the quickest way to get the "game clear condition" (setting hard mode), which would be through level K-1. You can also set the value to 32 (hex $20) to go straight to X-1. X-1 is just 8-4 but the pipes and loop points are broken, so you can just run to the end of the level from the first room."

[@Xtermo]

So… Tennis% category, guys?

[@jennasloan396]

"Press B to select world"

[@Gameboygenius]

This a pretty interesting bug. The bug is that apparently then, SMB doesn't initialize the signature memory location to $A5, from what you describe. (I guess maybe so that A+start works across resets so it might actually be intentional?) So SMB would have a 1/256 chance of having the signature already in RAM on a cold boot, unless perhaps the RAM has an uneven distribution of random initial values. Have the patterns of the NES's initial RAM state been studied?

[@haruki_nyan]

To my knowledge, the NES's initial RAM values aren't truly random, but any patterns varies between consoles, and can even depend on ambient temperature or what was last stored at an address.

[@haruki_nyan]

As a side note, this feature/glitch is absent in the SMB multi-cart versions, as even though Mario's code is the same, the game selection screen initializes RAM.

[@IsoFrieze]

It doesn't work on Mario+Duck Hunt, but does work on Mario+Duck Hunt+Track Meet for whatever reason

[@IsoFrieze]

I've studied SNES memory a bit, but not NES. From what I know from that, there is a specific value that each memory cell likes to rest at, and you'll find it at that value 99% of the time after a long enough time without power. The shorter the power is cut, the more likely that data is retained (at a bit-wise level even). And yes like the other commenter said, it differs from one console to the other. The game does initialize the $A5 value, but it first checks if it's already $A5 to determine whether or not to clear out the last chunk of memory. And the reason why it does this check at all is because when you game over or beat the game, it essentially resets the game via software. So in actuality this check is more along the lines of "did we just boot up the game, or are we coming from a game over/game completion?"

[@GigaOtomia]

Couldn't you just set the value in Tennis to 07, and start at world 8 that way?

[@IsoFrieze]

Copied from another reply: "Yes you could. At the time of making this video I was curious about the quickest way to get the "game clear condition" (setting hard mode), which would be through level K-1. You can also set the value to 32 (hex $20) to go straight to X-1. X-1 is just 8-4 but the pipes and loop points are broken, so you can just run to the end of the level from the first room."

[@trevise684]

okay now put it on a hotplate

[@icychill105]

this could crack the speed run

[@sofia.eris.bauhaus]

tennis%

[@FatAlbertFanClub]

Another cool dive into this concept was done by pop fiction way back when (video here kzbin.info/www/bejne/eZaxm554f7itn8k ) But the cart swap method only works with the top loader and could possibly damage your cartridge, there are 256 glitch worlds, and through some coding with addons that only existed with the famicom you could much more easily access the worlds if you wanted to.

[@IsoFrieze]

It's possible without a toploader, and it's not going to damage your cartridge.