Secrets of the Nintendo Game Boy Boot Logo | MVG

The Nintendo Game Boy has a clever form of Anti Tamper that made it difficult for unofficial and bootleg games to be developed for it and it was all thanks to the Nintendo Logo thats displayed when you power on the handheld. Lets take a closer look at the Boot process of the Game Boy.
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Sources:
► fuji.drillspirits.net/?post=87
► gbdev.gg8.se/wiki/articles/Ga...
► catskull.net/GB-Logo-Generator/
► • Hacking the Game Boy c...
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#GameBoy #BootRom #Nintendo

[@yinge101]

I remember my second-hand Game Boy was a little dodgy, and Tetris would often get stuck on a corrupted Nintendo logo screen if the cartridge wasn't seated *juuust* right. Satisfying to learn why after all these years!

[@erwelcomcom7410]

Cool

[@MyRegardsToTheDodo]

SaChen somehow circumvented that, atleast for the original Gameboy. They produced unlicensed games (no bootlegged copies of original Gameboy games, the games were entirely unique, just not licensed by Nintendo) and when you put them in the Gameboy and start it up, the screen says SACHEN or COMMIN instead of Nintendo. They don't work on anything other than the original Gameboy, if you play them on the Pocket or any newer model they will sit on the bootlogo. They were actually pretty productive, releasing 20ish games, and even licensed them out to other companies. Some of these companies even added content to the game, and yes, that means porn.

[@glecyroy6886]

Chicken leg lettuce

[@DasAntiNaziBroetchen]

Your game boy just has dirty contacts or your cartridge has dirty contacts.

[@TrollGarlic]

@@DasAntiNaziBroetchen thx exact same thing happens. probably the sticker i tore off

[@tbk2010]

As a kid I (somewhat correctly) concluded from the GBs empty-slot-behavior that the logo was part of the game instead of the handheld. However, the reason that that I came up with was kind of the opposite of reality: I thought that Nintendo wanted to allow other companies to produce games of the system, but present their logo in the same way as their own. At the time I was playing mostly on my dads PC, and since MS didn't prevent anyone from making games for DOS I didn't see any reason why Nintendo would do something like that.

[@BoGy1980]

that's the 3DO for you ... meant to be an 'open platform", even the hardware was built by multiple companies. Also on the atari games didn't need to be licensed (at least the 2600)

[@JJ-qo7th]

When bad games get made for PC, you blame the game developer for making a bad game. After all, the computer manufacturer isn't to blame if someone makes bad software for their computer, and it's helped by the knowledge that computers do other stuff, like word processing, accounting, scheduling, and the like. But when a games machine has bad games made for it, the console manufacturer gets blamed for allowing a bad game to appear on the console, in a realm where all you do on it is play games. It was really damned smart of Nintendo to restrict licensing and maintain quality control over its products. Not to say that all of the games were good, but they had to be *at least* functional to get the Nintendo Seal. Moreover, Nintendo only ever gave out so many licenses to a developer at a time. If you wanted more licenses to make more games for the Nintendo, you had to pitch games to them, and you had to show a good record of making good games. There was another thing they did to trick some people in the US: They deliberately made the NES look like a VCR to get away from the visual stigma of looking like a games machine, even though that was literally the only thing it did. Once they cleared the hurdle and gained public support in the US, they ditched the VCR-loading NES and went with top-loaders for the SNES and N64. I guess toploaders are less of a pain to manufacture.

[@MyRegardsToTheDodo]

There are games where this actually happened. You might still find them on flea markets or on classified ads websites (craigslist or your equivalent to that). The company's name was Sachen or Thin Chen, a Taiwanese develloper that produced unlicensed video games for the Gameboy and the NES. Not bootlegged copies of official games, their own games, just without licenses. If you put one of them into the original Gameboy the bootlogo either says SACHEN or COMMIN. They don't work on the Gameboy Pocket or newer models. That company was pretty productive, releasing 20ish games for the Gameboy alone, and even licensed these games out to other companies. Some of these companies added more content to these games, and yes, that means porn.

[@matiasd.7755]

@@JJ-qo7th actually, some of the worst games ever are licensed and carry the big N seal of quality... So the logo check is obviously not to ban bad games to appear... The biggest income to these hardware manufacturers are not from console units sold but from licensed games.... The logo check is to make the game creators obtain a license, be it a good or bad game... It's a measure in only the seek for profit... And it makes the game you buy a bit more expensive....

[@Fuchsia_tude]

@@JJ-qo7th They also made a huge push to rebrand the Famicom as the "Nintendo Entertainment System" with its integral robot peripheral (even though it only played two games (and they look dull as hell)), marketing the NES as a toy, not a video game console, to parents for its US launch. Obviously children recognized exactly what it was and once Nintendo had used R.O.B. to successfully Trojan Horse the console into a successful launch in the US, Nintendo quietly dropped it without ever releasing another game that used it.

[@Alias_Anybody]

Working bootleg potentially equals trademark infringement... diabolical.

[@thorlancaster5641]

If I remember correctly there was a court case that ruled these checks unenforceable. EDIT: Commented too soon, Glad that the Sega case turned out the way it did.

[@Dinnye01]

@@thorlancaster5641 the sega saturn maybe? I'm too lazy to check, but our own MVG made a video about this.

[@Dinnye01]

*genesis

[@theonik2006]

That's the whole idea.

[@kasperfabchbrandt537]

Sega v. Accolade: en.wikipedia.org/wiki/Sega_v._Accolade

[@niino4329]

I like how you correctly said "The north american video game crash". Many people (including outside north america) mix this up and think it was an international thing. Like some kind of Mandela effect.

[@AndehX]

Yeah there definitely was no video game crash over here in the UK. I remember quite vividly playing the highly successful Spectrum in the mid to late 80's and Atari 2600 going into the 90's. Gaming was quite popular in the UK in the mid 80's

[@arturstatkiewicz6360]

For some people North America is the whole world.

[@Brianreese83]

We had Reagan, and economic issues really bad at the time, a crack and aids epidemic, record unemployment. A lot of folks were trying very hard to pay the bills and just didnt have the extra income for games. Let alone shitty ET. I digress. Was more economical than it was people didnt want to play games. Plus we had arcade machines all over (one thing I really do miss from the era). Was easier to afford a couple quarters than buy space invaders for 39.95 and an Atari for a couple hundred bucks.

[@CityStarrzz]

@@Brianreese83 absolutely not true. The crash was due to corporate greed, and companies trying their hardest to commercial this new commodity. There’s is always a cost to the kind of behaviours exhibited back then, and the western world continues to try and prioritise money over quality regardless of the result. We’ve done this with food too, the only difference being that food is required to survive so we still buy what we can afford, and end up sick or unhealthy in the long term. America especially is an absolute hotbed of immoral decisions made to support a corporate ideology. Hence why it’s run by a president who claimed to have had coronavirus, and then claim his cure was potentially related to a medication he himself had a vested interest in. The uk isn’t far behind, so I’m not acting like we’re great, but that particular crash was definitely caused primarily by those practices.

[@colt1596]

@@arturstatkiewicz6360 lol being from America I can agree with this. More patriotic then conceit though. One of the reasons I love borders. Culture is a beautiful thing.

[@H2SO4__]

9:10 i like how he talks about precision timing while he himself is out of sync with the video

[@vanillacokejunky]

i believe that is a clip from something else with the audio muted, he is just recycling old footage and speaking over it.

[@Fuchsia_tude]

@@vanillacokejunky It's a kind of odd decision and it stood out when he did the picture in picture earlier in the video too.

[@-DeScruff]

I do like how it also acts as a 'dirty pin connection' test, just so you know if a game boots up, your not gonna have weird graphical corruption issues or something that you sometimes get with the NES.

[@hardgaming8541]

Not really, I had a Donkey Kong cartridge that kept switching areas randomly after finishing one, some enemies and objects also were kinda like swapped by black rectangles.

[@silkwesir1444]

Which is of course just an accident, a consequence of the protection erring on the side of "caution" (from the POV of the rights holders)

[@BikerLordCarnage]

This used to be a nightmare to support... Developers would change the logo data in one of the SDK .S assembly files and then raise a support ticket asking why their game won't boot on the devkit. We had to write custom tools to checksum the logo in the executable .ELF file and even replace it with the correct logo data to verify the fix. Why it didn't come as a pre-assembled object file in the SDK, to discourage editing, I don't know 🤔

[@BikerLordCarnage]

@randomguy8196 Well, that would've been a start I suppose :-D

[@Mendaz]

Did you used to be a developer for Gameboy games, if I may ask??

[@BikerLordCarnage]

@@Mendaz I used to support the development tools for Nintendo consoles.

[@Mendaz]

@@BikerLordCarnage Ah, now it makes sense why you would know how it was such a rampant issue. Lol Thank you!

[@userPrehistoricman]

@@BikerLordCarnage Was there no hardware debugger that would tell the devs that the gameboy was stuck in the boot ROM?

[@rolandkatsuragi]

Nintendo never ceases to amaze me with their anti-piracy methods

[@jonathanrmz2993]

You heard of apple? Haha

[@thewoo9894]

@@jonathanrmz2993 wym.. shits hard to fucking pirate.

[@bowduh]

Laughs in wii

[@TexasHollowEarth]

Then there's the Switch! 🤣

[@raven.4815]

Then a simple clip killed any security on the switch...

[@ChiekoGamers]

Next episode: How PS5 security was defeated using chicken nuggets.

[@gustavovasconcelos9857]

*Mistakes were made*

[@Tobi_DarkKnight]

How the PS5 security was defeated with air.

[@TylerFurrison]

Don't give the hackers ideas

[@astafire6810]

@@TylerFurrison you could technically use the oil from those nuggies to short a capacitor and override the disk security

[@ADeeSHUPA]

@@astafire6810 アスタ 파이야

[@taiwanjon2583]

I'm happy to see you mention Taiwan! As you hint at in the video, at the time Taiwan's copyright laws were not very strong, but Taiwan did have strong laws protecting trademarks, which is why they required a Nintendo logo to be displayed in order to boot the game.

[@MarcoGPUtuber]

Next Episode: How security on the Game Boy was defeated and how I modded the Game Boy to say Modern Vintage Gamer upon startup.

[@IngwiePhoenix]

He literally explained it x) Catch the first read and act differently upon the second. :)

[@MarcoGPUtuber]

@@IngwiePhoenix I mean a more detailed history of it in a dedicated episode.

[@Quicksilver-7791]

You watch mvg too? I see you every comment section of bryan's videos

[@MarcoGPUtuber]

@@Quicksilver-7791 Gotta support the YES!

[@h.b.5577]

@@MarcoGPUtuber Fancy seeing you here as @Harjas Singh already pointed out. How have things been going on in Taiwan as of late?

[@cloudsquall45]

Used to love changing the color palette on my GBC at the boot logo, pokemon red in Up + B red was so much better. I'd sit and stare at the logo while changing all the colors

[@colt1596]

I accidentally figured this out playing superman on GBC. Didnt use google back then, so I just kept trying to find color codes. I'm glad you commented on that. Nostalgic lol

[@cloudsquall45]

@@colt1596 Yeah, here's a list, if you still have a GBC/GBA nearby i.imgur.com/jZUXMp2.jpg www.nintendo.com/consumer/systems/gameboyadvance/colorchange.jsp

[@christiangomez7947]

I always played tetris on blue or pastel.

[@cloudsquall45]

@@rap6439 NGL, just dug out mine too and sat and spun the dpad for ages.

[@christiangomez7947]

@@rap6439 nah, i've got an advance(original)

[@ZygalStudios]

Cost was definitely the main reason that a CIC chip was absent on the cartridge. But something that also makes me wonder is board space. Seems pretty packed on the cartridge PCB and anything more would require mechanical changes across the device slot and cartridges well as software changes too. Great video!

[@alexholden]

Could also be related to power consumption given that it was battery powered.

[@ZygalStudios]

@@alexholden Very true!

[@lainwired3946]

GBC and GB carts have a fair amount of dead space generally. I think it's just costs like you said. You could deffo fit a small chip into every cart I've opened over the past 30y

[@erik19borgnia]

@@lainwired3946 that's only on games that didn't have ram+battery, those have some free space. But in the video it shows a cartridge where there is not enough space to put another chip, and games like that are quite a lot.

[@lainwired3946]

@@erik19borgnia What makes you think you couldn't fit a simple processor on there? It doesn't have to be anywhere near the size of the banks

[@choccymalk123]

Nintendo: Look, we have a secure system! Modders and a soldering iron: No

[@TylerFurrison]

Yeah, it's funny how modders managed to figure it out and bypass it

[@soursugar4867]

Nintendo with the Wii: You cant defeat me Hackers and home brew designers: I know, but he can *T W E E Z E R S*

[@TylerFurrison]

@@soursugar4867 just look at the 3DS... It was broken with a crappy game

[@soursugar4867]

@@TylerFurrison Their game was so mediocre it literally broke the system security

[@MultiWirth]

@@TylerFurrison Just look at the Nintendo Switch (first gen). Security didn´t exist at all thanks to nvidia´s recovery (flash mode) from the android world...

[@soullessleftover8427]

I always love a creative boot logo/animation. Some of the more popular pirating groups used these, and when done right. It looks awesome 👏.

[@sethtaylor1251]

I love the way you put your videos together man, the quality is close to tv shows like ‘how it’s made’ or just any high budget short-documentary. It doesn’t go unappreciated!

[@jansenart0]

The boot logo solution was pretty brilliant, for what they were trying to do, which was to eliminate any large-scale licensing-avoidance from someone like Tengen, like they had on the NES.

[@SgtJoeSmith]

Lock picking lawyer unlocked the game boy security in 4 seconds using a banana

[@teh_supar_hackr]

MVG and Lock Picking Lawyer compete against each other to see who can unlock a game console the fastest with just some McNuggets.

[@Geneo-en5km]

The in depth description and showing us how all these different ways these systems do what they do amazes me and keeps me coming back for more

[@Illya9999]

Wow thats really interesting! I never would have thought that console manufacturers would put drm in the boot screen

[@Schmaglow]

You should watch his video on the original playstation then

[@AnonymousGentooman]

Drm is meant to limit/prevent copies, this is perfectly copiable infinitely, just ilegal to do so by virtue of being a trademark

[@Kalvinjj]

@@AnonymousGentooman ain't it the exact same effect in the end then? Also, I might be terribly wrong but isn't that the job of encryption, along with DRM? Tho given they usually (if not always) work together that distinction might be moot indeed.

[@AnonymousGentooman]

@@Kalvinjj No, because DRM is meant to prevent an illegal copy of a piece of software being made, for example, Steam is DRM, you cant just copy the game to your buddy's computer, if he doesnt have Steam and the game in his account, it will not play. This however, is a very small, easy to copy code, needed on every piece that wanted to run on the Gameboy, so if you wrote your game from scratch, you'd need to add it so it would play, becoming copyright infringement, it doesnt prevent copying, it makes it so you (in theory, because video shows it was circumvented) cannot write a Gameboy game without infringing on nintendo's copyright

[@Kalvinjj]

@@AnonymousGentooman hhmm... I see, I get the distinction now.

[@maybedonn]

I just want to say this channel has been killing it recently with the content. Keep it up.

[@jaredloveless]

"16 bits is equivalent to 64 kilobytes" What I think he's trying to say is 16 bits are enough address locations for 64 kilobytes

[@LEGOpachinko]

I was confused when he said this

[@Asdayasman]

Pff you're just not using good enough compression.

[@weir9996]

And later on screen it says "64kb" which would be 64 kilobits not 64 kilobytes

[@akaDL]

I've came accross to one of your videos at random, but I got addicted. As a novice programmer that wants to code games in the future, i feel amazed by the sheer aumont of hidden secrets and knowledge you're sharing with us. Keep up with the good work!

[@bid0u12345]

I really love your videos. They're always a bit complicated but always come with an easy to understand explanation.

[@bebenlebricolo]

1:20 : one of the GoldenSun titles booting up. Such good memories!

[@MichaelPlante87]

I though it could have been either mario golf or mario tennis, but no, the intro aren't the same. Golden Sun ftw!

[@mjc0961]

Glad I'm not the only one who caught that.

[@AwesomeHairo]

Literally playing Golden Sun now

[@EEVOL]

It's ironic that this video comes out when I am playing on my Play It Loud green Gameboy. Thanks again for another wonderful video MVG!

[@tzaan]

I thought this video was really nicely made and also I didn't know the Gameboy had piracy protection so thank you for that, keep making great videos and have a great day

[@Cav95]

I truly love this channel. Keep up the good work!

[@unexpecteditem7919]

Not putting the 10NES in the Game Boy could also be because of battery life - having to power two extra 4-bit CPUs that are constantly handshaking could've absolutely slaughtered the batteries, so maybe they took that risk to not include it.

[@RafaelSolMaker]

Huh, new MVG upload! Time to watch. Have a good one, everyone!

[@baconology3065]

i really enjoy the content you create, it is at a perfect technical level for me to understand, illuminating, engaging, very much appreciate your work, hope you are benefiting well from the platform and it isn't ripping you off.

[@cemawi]

Informative as always! Keep up the great work

[@sekainowaluigi3249]

Interesting. I knew unlicensed games often used custom boot logos, but I had no idea that required custom hardware!

[@joekenorer]

I remember when I was a kid that I could tell if a game was going to boot or not by what the logo looked like. All these years later I learn why. Thank you.

[@sonic2000gr]

Great content, loved the detailed explanation and the disassembly of the boot rom!

[@desudesu52]

I really like the way you explain things, clear and effective

[@Beaudunk]

Man I love this guy's content.

[@nothingtoseehere93]

The best part of waking up on a Monday is an MVG video

[@gravy1219]

I discovered your channel recently after watching LGR and i am hooked, Thank you for your content :)

[@dave_s_vids]

Fascinating stuff! This is my favourite kind of content that you do. Keep it up please!

[@rretard308]

I can imagine someone selling a game boy cartridge to someone, but they edit the logo to say " *YOU JUST GOT TRICKED* "

[@m2pt5]

If I remember correctly, the GBC Mega Memory Card had a modified logo. I had one back in the day.

[@AWalYT]

Yep, it says megamem. Fickle thing to boot, but then again, most cheat tools are lol.

[@jolness1]

As always, excellent video. Thanks for the amazing content!

[@kadosho02]

Always wondered about the logo, and it was more than a simple boot up screen. Fantastic to know it's capabilities, and the process that seems so simple, is intricate inside.

[@rhodexa]

Just what i was wondering minutos ago. Perfect!

[@bryanfrye8770]

I want to hear the story about those guitars in the background. Do you have a channel that showcases your talents?

[@vap1777]

He makes the music in the background

[@ControlAllDa1337]

A lot of these videos go over my head but I find them all so fascinating

[@SvennyMcG]

Love these videos and, even though I don't understand code, how technical you get into the deep dives. Keep it up and I'll keep trying to follow along 😅

[@EpicEmberOriginal]

I'm guessing a mistake or two were made

[@StraightOuttaJarhois]

Reading the code two separate times, thus allowing the possibility to swap it out, does seem like a mistake.

[@EpicEmberOriginal]

@Mike UK Uh, sorry, what?

[@akaDL]

​@@StraightOuttaJarhois Allowing the possibility to swap it out isn't a mistake, since injecting code is done on non common/standard/legal ways. There isn't a single system in the world that is 100% bullet proof. However, the close you are to the 100% mark, it costs billions to provide such protection. It doesnt matter if it was checked once, it would still be possible to swap the code anyway, bypassing the protection. However, this protection was simple, clever and cheap, and it worked out for the most part. Like MVG Said, Nintendo is aware that it is impossible to stop piracy/bootleg, but adding a simple and clever protection to hold off bootlegers for a week or two after a major release, was worth and it did it's job.

[@Architector_4]

@@akaDL Though to be fair, having it read the logo for displaying, and then immediately check it, and only then start displaying it, would probably make the protection way more effective, even if still not bullet proof.

[@davidmcgill1000]

Only mistake I see is using a checksum that could be recreated with a not trademarked image.

[@bradmonk69]

If Nintendo made a commitment to only allow quality games on their system, then how does that explain the masses of shovelware for purchase on the eshop?

[@SuperLuigiGuy64]

Simple, this isn't the same nintendo from the past. This a new nintendo, a shell of their former selves sitting on stacks of money and still have yet to improve their online infrastructure.

[@31redorange08]

For example Pokémon Sword and Shield.

[@LonelySpaceDetective]

Even back in the NES days, the Nintendo Seal of Quality wasn't exactly a guarantee of a good game. The NES certainly saw its share of mediocre low-effort cashgrabs, despite Nintendo's claims of quality. I saw the purpose of it as being more for the retailers; to reassure them that Nintendo had a better grasp on what was allowed to be released for the platform than Atari did and that a second video game crash wasn't going to be happening on their watch. The video game crash really killed any interest in the industry from stores!

[@Matanumi]

@@31redorange08 ....that's more of a game freak QC and mannagement issue

[@LonelySpaceDetective]

@@Matanumi To be fair Nintendo still published it and presumably funded it to some extent. Hyrule Warriors was primarily a Koei-Tecmo project, but Nintendo still oversaw its development.

[@foxhoundra6444]

Always gives me such a relaxed feeling listening to cool MVG stuff :p

[@ToranosukeEdo]

Fascinating. I love your content so much 💙

[@Niko-ex3bn]

Having written a gameboy emulator, getting the loader to run correctly was a good first trial to ensure that it worked properly. If it didn't boot the game, then I knew one of the opcodes in the loader were wrong. That was a few sleepless nights to say the least.

[@emperorofgaming8146]

What emulator did you write, and where can I download it? I’d love to use yours out of the others.

[@Niko-ex3bn]

@@emperorofgaming8146 As much as I can say it emulates, its not perfect in accuracy and has a lot of bugs that likely wont be resolved as its just a pet project.

[@illytothaj]

Due to the limitations of the older systems I get the feeling that game creators where more creative to get more out of a system then with the current consoles / handheld. Or am I wrong with this assumption?

[@soursugar4867]

They definitely had to work a bit harder to actually put it on there, yeah. Making a game is still difficult, but not nearly as difficult as it was in the 80s and 90s

[@Kalvinjj]

Sure as heck they couldn't brute force their stuff to work with sheer power, but games that were badly programmed existed back then as well, with slowdowns and all. Nowadays we got so much power you can hide some bad coding decisions for sure but not all, not to mention full game engines that handle a big part of the heavy coding.

[@ThePrimo80s]

Love your videos mate. I always learn a lot from them.

[@ezequielchehda5092]

Watching this before going to work has no price! Thanks for all your hard work!

[@Erwiinstein]

I just want to know if mistakes were made or not. EDIT: After watching it, I still can't tell if mistakes were made or not. In all seriousness, amazing video as always.

[@Wkterr]

There was one mistake: If they had loaded the logo from the cartridge into RAM instead of reading it twice, it wouldn't be possible with custom logos (and thus bypass having the Nintendo logo displayed). But the mistake was insignificant, not many bootleggers used the method and in the end the Nintendo's (and Sega's) scheme was ruled inefficient anyway. So basically the lesson is: You cannot use copyright or trademark laws to prevent unlicensed software.

[@SpennisTheMenace]

Shout out to consoles before needing $90 and 5 hours of downloads/updates to play the basic version.

[@Mario03020302]

Most characters hair rendering need more processing power than the GameCube had

[@aimwell8813]

If you don’t like downloads and updates, and don’t like the price of modern console games, you should really consider the Oculus Quest 2. That’s the closest modern console to the opposite of your words

[@laurinneff4304]

@@aimwell8813 warning: you need a Facebook account for the quest. Might not be an issue though since they probably already have all the data you'd put into the account

[@user2C47]

@@laurinneff4304 Facebook probably knows all of your personal information and secrets, as well as everything you say, do, and think, even if you don't have an account.

[@Wkterr]

Haha, I love it. I've seen the bootrom disassembly, but never paid much attention to it. The moment you said "The logo is read twice" I immediately though "So in theory I can change the logo between reads". Funny how this brand new idea I just came up with is older than me.

[@CallMeSugarMilk]

Love your videos MVG. Always intrigued by them and your teachings/explaining of said topics are so interesting to see and hear! One day I would love to see you do a video about Sega Smash Pack Volume 1 for the Dreamcast and how poorly SEGA emulated it's Genesis games on there (the sound emulation specifically). That's a Dreamcast game I grew up and still love to this day (surprisingly the poor sound emulations don't bother me since that's how I first experienced Sega Genesis games when I was little so at this point, I like both weirdly lol). There's also an interesting document file you can find if you insert your Sega Smash Pack Volume 1 disc into your computer and dig through the files that I would love to see your take on it and overall explain in your thoughts, what exactly happened with the emulation and how could something like this be approved by SEGA even when they announced already that they were discontinuing the Dreamcast. Keep up the amazing work regardless! Look forward to all your videos :)

[@JoseMedina-hs9st]

I never knew that the Nintendo logo was some type of anti-piracy I thought it was just a normal logo

[@silkwesir1444]

does that mean you never had a game fail to boot up because of dirty connectors?

[@renakunisaki]

The checksum is unrelated to the logo check. It's just a redundant integrity check. Swapping out the logo after it's displayed has nothing to do with code. The game code isn't running at that point. It's entirely done by hardware. Although the logo swap worked on GBC, it changed the timing and did a second check, so doing it was more difficult. Bootlegs that used this trick before the GBC wouldn't work on it. On the other hand, for some reason the GBC only checks half of the logo. That's why some newer bootlegs have logos that are poorly edited from the original.

[@wojtekpolska1013]

im kinda grateful this happens, when i buy a game online, usually the contacts are pretty dirty and i have to clean them with a cotton swab. the logo can tell me when i cleaned it properly, so the game runs without errors if the console cant properly read the Nintendo logo, it means there is trouble with the connection, so if the game tried to run it wouldn't work properly

[@BlessedDog]

I love your videos. Keep it up man!

[@stefanocrespi5424]

Amazing someone re and implemented it in the emulator. Emulation is such both a skill and love evidence.

[@freshstat1csnow]

Emulators allow (or sometimes even require) people to provide a boot rom dump so all it has to do when one is present is emulate the communication between it and the loaded game rom. This means that if the game is edited or corrupted in some way it will behave exactly like it will on real hardware.

[@Centbair]

Here I thought the black bar logo on the gb, when you have no game inserted, was the system saying "You forgot to push the cartage down all the way." Nintendo ninjas

[@wazza-au]

Thanks for an excellent video. Like a lightbulb going off every time I watch one of your vids.

[@pjousma]

Your stories are always interesting man!

[@Carighan]

But would this really be anti-piracy? I mean you just have to edit two addresses instead of one. And I mean, they're right next to one another pretty much. This feels more like an actual checksum, the chance of any weird pins or so changing both images in the same way is practically nil, so there's a good way of knowing whether things load correctly. I know Nintendo did a lot for copyright reasons, but this somewhat feels more like an actual error check.

[@LiEnby]

yknow pirates dotn really care about trademark violations xD

[@guerht]

Hmm why doesn't the gameboy read the already loaded characters in the VRAM instead of going back to 0x0104 when validating the logo? Could it be due to efficiency issues?

[@Jimbaloidatron]

Came looking for exactly this comment; my immediate thought was that if they'd checked it again in VRAM, you absolutely know that it's been displayed, possibly with a half second delay between checks. I guess they didn't anticipate anyone adding the extra logic. These things are an arms race.

[@erik19borgnia]

In the GB/GBC, you could've access the VRAM only during Vblank. If you try to access it in any other moment, it will just give you garbage data (FF specifically). So if they wanted to do that, it will make the bootstrap more large and complex and that probably was not ideal. Seeing that the original bootstrap has exactly 256 bytes kinda confirms that. In the GBC it's even funnier, because it just checks half the logo xD

[@user-ij5sm2wk7y]

The logo has been pixel-doubled by the bootstrap ROM when it was sent to VRAM, so a routine reading from VRAM would have to undouble those pixels again. Also not efficient.

[@erik19borgnia]

@@user-ij5sm2wk7y I forgot about that detail, that's another reason :P

[@ThunderFist1978]

Wisdom Tree, who made Christian games for various consoles in the early to mid 90s, made a few games for the Game Boy. I have Joshua and the Battle of Jericho, and when that is booted up, the Nintendo logo comes down the screen just like with any other game, and after the sounds typically played, the Nintendo logo stays on the screen for a few seconds as the text “is a trademark of Nintendo Inc.” or something similar appears under the logo. That’s how Wisdom Tree handled their games on the Game Boy.

[@cakranid]

this is amazing video. not only describe how this is works, this do even more to hack the visual appearance .

[@stopandlisten6070]

"Nintendo had set out to put their stamp of approval on any licensed game and make a commitment, that it would be a game of a certain level of quality" *Looks at Switch store flooded with trash shovelware that are basically Hentai click games on a kids machine* Oh how times have changed.

[@itsstudytimemydudes4345]

gosh, really? he said this line and my mind went to all the odd DS and Wii shovelware games that were released, like the Silly Bands game and the Minion Mayhem game oh how the giants have fallen-- its a huge shame but Im hoping Nintendo's standards for approval will improve again

[@EpicEmberOriginal]

If I ever make a Gameboy game I'm hacking the bootloader to say PlayStation

[@andybunn5780]

The Gamestation

[@gustavo_vanni]

@@andybunn5780 Or PlayBoy lol

[@alexg9601]

Yes, please Do it

[@koppo5657]

@@gustavo_vanni oh goshh

[@WrestlingWithGaming]

Fascinating stuff as always, MVG.

[@piorism]

Great content as always ! Fascinating topic. It would be interesting to see a breakdown of the assembly code from the comparison loop. As someone who doesn't know a single thing about that kind of language I find it visually really elegant since there seems to be no syntax errors possible ...

[@Dreamwriter4242]

I was an old GBC developer, I can help you with some of that. A bit of "backstory": most functionality in Z-80 assembly language is based on loading data from a memory address into "A", and then doing something with A, and storing the results elsewhere. You can store a memory address into "HL" or "DE", and then read the contents of that memory address by loading (HL) or (DE) into A. The video around 7 minutes in shows the comparison loop - before that code is run, DE is set to the memory address in system ROM where the logo is stored, and HL is set to the memory address on the game cartridge where the logo is stored ($104). LD A, (DE) ; Load a byte from DE, the logo in system ROM, into A INC DE ; Increment the address DE, so next time we read it'll be the next byte of the logo CP (HL) ; Compare A with the contents of the address stored in HL, the logo on the cartridge JR NZ, $FE ; A bit more complicated - the CP command actually subtracts two bytes from each other; this command says that if the result of the CP subtraction was non-zero (NZ), to "Jump to the Routine" (JR) at memory address $FE (which presumably would cause everything to stop running, because the two bytes weren't the same value). INC HL ; Increment the address HL, so next time we read it'll be the next byte of the logo LD A, L ; Load the second half of the HL address into A CP $34 ; Does L = $34? Then we're done checking the entire logo, because we have incremented HL $30 times (remember, HL started at $104, so incrementing HL $30 times = $134) JR NZ, Addr_00E6 ; If A was different from $34 (A minus $34 was Non Zero), then Jump to the Routine back at the beginning of the loop and do it again I won't go line by line for the next section, it's more complicated, but basically it does a second check: it starts with $19, and loops through $19 times reading each byte from the cartridge logo and adds that byte to total, and once it has done that $19 times it once more adds one more byte to the total, and if at that point the value of the total hasn't wrapped around to exactly zero, it jumps to the routine at address $FE to stop the game from running. This is known as a Checksum test, checking the sum of a bunch of values to see if the result is what's expected when adding all those values up.

[@piorism]

@@Dreamwriter4242 Hello ! Thank you so much for taking the time to go into such depths, this is fascinating and highly appreciated. And above all, thank you for all the entertainment you contributed to by working on these GBC games !

[@Xerho]

It infuriates me, how you dont hold hold down the B button and press A with the other side of your thumb.

[@TokyoXtreme]

I use my right index finger for B and my right middle finger for A. For a Gameboy, I'd use my left hand in the conventional manner, but on a NES controller, I'd use my left index for D-pad right, and my left middle finger for D-pad left (thumb would be underneath, on the bottom of the controller, to add support).

[@IgorCalheiros10]

@@TokyoXtreme C U R S E D holding

[@twerlertsperglesperblenerb9826]

@@IgorCalheiros10 I can top that: right index finger on dpad, middle finger on B, ring finger on A, body of gameboy gripped with thumb and pinkie. What's the left hand doing? Best if you didn't know...

[@gblargg]

9:57 Who plays Mario without holding B down the whole time? So slow!

[@dsuess]

Great video! Always enjoy your breakdowns. Would you be willing to make a video on your favorite emulators/debuggers that you use for classic consoles, and how you use them?

[@TrialzGTAS]

I wait up an extra hour work for your uploads 🤙🏻

[@pnnytx]

LiveOverfl0w explained this before, but this is better.

[@yendayo]

Game Boy Knowledge: Max level Game Boy Play skill: level 1 jk btw, love your vids.

[@xXm33masterBadXx]

Great video as usual very interesting!

[@Darth001]

I love videos like this. Keep it up mvg

[@TysyTube]

👍👍👍👍🔥 i restored the first game boy ❤️

[@gacgac]

nice

[@khatharrmalkavian3306]

"16 bits is the equivalent of 64 kilobytes." Oh gods, here we go again...

[@gregorymalchuk272]

A 16 bit address bus has 2^16 address possibilities, or 65,536 bytes, provided the computer was built to handle 8 bit bytes.

[@evanmbxx8897]

Thank you for this video!! Explains a lot.

[@VK2FVAX]

Nice walkthrough in the code. More of these please :)

[@Ziggurat1]

I love your videos, they are simple yet effective :) Also love your advance videos too, not many can make coding look fun (coding is fun, it doesn't look fun)

[@andytabor3829]

Awesome content as always 👍🏻

[@authentic6825]

What a simple but clever setup... And then a clever but simple workaround!

[@juanbermudez964]

Man!! Thank to you a had learn a lot of things that I never imagined

[@unixtreme]

Thank you for all the free high quality education, you are a rock star.

[@TheMr77469]

Nice! The code explanation reminds me of stuff from Retro Game Mechanics.

[@RetroActiveGM]

I love this god damn channel. Keep up the great videos, man.

[@gammleraffe]

Congratulations to 500k 🙂👍🏻

[@santinobardz7398]

never failed to amaze me. good job mvg!

[@lerodkazuko4391]

I could see all the assembly programming in the code you were showing and yes, the consoles after Atari and the lack of licensing is what caused developers to take action to prevent this sort of thing of infringement from happening. It's all simple code for validation that happened during the boot process but with some precision tweaking and timing that can be circumvented as you mentioned.

[@iminimal86]

awesome video. many thanks for all of this !

[@Gabe-es7io]

Very interesting stuff. Never would have thought so much was going on when that logo dropped on the screen. I'm currently in plans of restoring my Gameboy. Hope I succeed 🤞