Code Walk! CPU Cycles and Performance of Mega Man 2 (Bonus: MM3) - Talkin' Code Ep. 4 

Exposition on MegaMan's X-Position. I'm here for it. * taco crunch *

Debugging tools like this would have been amazing back in the day.

The disappearing/reappearing blocks are the bane of my existence. I hear the "vzzzzshwp vzzzzshwp" noise in my sleep. Learning more about them has not helped.

I don't code, I never learned any programming language, but with just a cursory understanding of the very basics, your explanations make things perfectly clear. These videos are so fascinating and entertaining to watch! I love peeking under the hood of these games, seeing what makes them "tick". It's the same sort of fascination I'd have when someone breaks down a car's engine and explains what each little tidbit does and how it affects the whole. Thank you so much for making these! Can't wait to see what you do next!

Grab a taco, your favorite beverage, were gonna do a code walk is my new favorite line. I plan to use it at my next code demo.

$F9 sort of acts as an underflow/overflow for Y coordinate math. I've seen it used like: 0E:8C29: AD A0 04 LDA y_pixels[0] 0E:8C2C: 69 0C ADC #$0C 0E:8C2E: 85 0A STA $0A 0E:8C30: A5 F9 LDA offscreen_underflow 0E:8C32: 69 00 ADC #$00 0E:8C34: 85 0B STA $0B Theoretically it can be positive, but Mega Man always dies when that would happen.

This video is fantastic. Mega Man is my favorite game, as a developer I love NES development, and the ability to have it all told to me as a story is great. Please keep doing videos like this and Behind the Code.

I'm totally digging this series! I really appreciate all the code walkthroughs. As I delve in code myself, I don't ever do this low level of programming though, and I truly find it super interesting and entertaining. I also realize you don't want to take 2 hours to go over every single detail in the code that's there. Thanks! And keep up the great work!

I never recognised the shine graphic on those blocks before. It goes so fast but I can pick out at least 3 frames. So imagine the blocks skip through three tiles before disappearing. If this game was a rush job you gotta appreciate the small details the developers invested in it with what little time they had.

The marked breakpoint visualization is an awesome feature, wow! And the graphics you made and showed to the side of the code walk really helped!

I remember from your mapper video explaining how the MM3 in Mario 3 allowed the slot machine video game with interrupts. when I saw the alternating directions of scrolling in the level select at 24:30, I thought that must be a different mapper, which you soon confirmed I am retaining information from these videos.

I really appreciate the level of detail and depth in your videos. You've revealed many of the secrets that I've wondered about since I was a kid and a fledgling programmer. Many thanks.

I would love to see you look at the bank switching on Zelda 2 to see what could have been improved, or what caused the slowdown in the maze potion of the overworld VS the NDS version. I know i saw you mention it in a previous video. As always, great content!

I always enjoy code dives like that in old games, really shows how things have evolved, and how much knowledge we gained throught the years, for the very same subject

I've looked at that bubbles and splashes subroutine. It's about what you'd expect--most interesting part is that there's a couple of little tables that store different gravity values for air vs water.

18:55 We know what typewriter is, we are not that young :)

I heard Mega Man 3 development was insanely stressful with many staff walking away during or after finishing it. you can kinda notice it in level design. Starting with Wily stages you really start feeling like they are first drafts and not iterated on at all. In some ways Mega Man 4 feels like first Mega Man game they actually finished.

Inefficient code? Have you heard of the infamous kusoge Maka-maka for the Super Famicom? One of the features of the SFC was DMA. The programmer on that saw that and got the exact WRONG idea of how to use it. It is an RPG, and whenever transitioning to or from battles, the game has some incredibly long load time, especially for a cartridge game. I don't know if I've even seen worse from CD-based games. I remember finding the load times in the PS1 port of Chrono Trigger excruciating, and yet they're still not as long. During the graphics decompression routine, the program uses DMA to registers to write a single byte to RAM, while it uses looped code to individually clear out 64KB (half of WRAM), and it does that many times during one graphics loading sequence. I have patched that game's graphics decompression code. And while not dealing the excessive wiping of WRAM, just patching it to make sensible use of DMA was something like a 40% speedup, if I remember the timing comparison right.

I just started developing NES games, so this is the best channel I could have found right now. Amazing work, man. Amazing.

Really comes together at the end there with the visuals for sure. I have no idea what tools they used to make these games but not having that level of control over debugging etc probably made it harder than it needed to be

Megaman 3 was absolutely rushed out the door too, sad to say. It`s actually amazing that it managed to be done as well as it was, all things considered.

Love this series of videos! Keep it up!

The mysterious M toggle is mysterious no more!

I'll be honest, I don't understand half of what you're saying most of the time, but it's still very intriguing to me for some reason! I'm a computer geek, I can build them and use software proficiently, but I could never get a hang of diving into the code. I've dabbled in it a little and I can pick up on some of the things you talk about, but I wish I could have your depth of understanding in these things. Anyway, I really enjoy your videos!

This series is simply awesome! Learn how to achieve those features, long ago, with so little resources, shows the ingenuity of the developers of the time!

I'm always amazed at the depth of your work. Kudos!

this video just emphasizes how ridiculously fast computers are compared to us. Even this 8bit system seems to be doing a metric ass-ton of work in microseconds of time, even though on the surface it looks like its extremely basic. Despite being a techy every once in awhile it just baffles me how computers can behave like this, and cannot fathom the more modern machines.

i love this channel, i like it not beeing edited too much, i like it beeing nice to understand, i like it it's a small channel, but maybe that just enhances it thank ya

Love the code walk - been trying to make a Megaman game myself !

This is one of the best videos I've ever watched on youtube.

You can dedicate all future videos to mega man and I for one would not be disappointed :)

Another fantastic video =D

Another great video. Had to save it for the weekend to be able to really focus and try to get it. And Mesen, man, what a great emulator!

I have no idea about assembly code yet i am intrigued, first time i saw any assembly was when using cheat engine to make some basic cheats. now i'm interested to see how it works! awesome stuff. Oh and i have no programming experience so this is hell but also fun ;D

Can't wait until you tackle Back To The Future NES and why the music is double-tempo compared to what it should be!

The Micronics burn was the icing on the cake of this delicious dive into the performance of Mega Man 2. Thanks!

Way back in the day (snes98 / 9x) ) on dos, I used to create my own pro action replay codes using the built-in cheat engine, it's so cool to see the code behind what I was doing on similar games.

Loving these code walkthroughs. Really good info. There's also a MegaMan 2 MMC3 hack (probably several of them), that would be interesting to compare. The Gameboy MegaMan games also have similarly sketchy performance, but on a smaller screen with arguably more CPU time per frame. I bet they have some NES concepts ported over that could be fixed by rethinking it in the frame of the GB's style.

I _love_ these videos!! One request --- I'd love to know more about the enemy behavior patterns (common ones and bosses) and how they relate to hurting Megaman via collisions! PS: (Maybe a quick rundown video of assembly/Mesen, linked in the descriptions, might help people to better follow these quick rundowns.)

Ow, my favorite video type!

All the little bank switches flying by is like a sandstorm

Always thought Mega Man 3 was off, always had to use a fan patch to enjoy it.

That optimized megaman 3 looks so good! I need more info! (and a flashcart lol)

I really love your style of videos! Please keep it like this! 💙It's really interesting to learn how different mechanics were coded, I really play around with cmd code so a lot of these techniques I can use too!

Yeah, on the code-walk, on the code-walk, yeah I do my little turn on the code-walk I'm a programmer, you know what I mean And I do my little turn on the code-walk Yeah, on the code-walk

I'm only a rank amateur when it comes to coding. Didn't 100% follow everything on your code walk, but even I could tell that code was bloated and inefficient! Fascinating video, as usual!

never have a clue what youre ever talking about. but i love listening

You make me want to dig into this debugger, and get a Game Genie-device, and look into what awesome changes can be made with just some codes.

Thanks!

It's nice to see someone mention Recca. Unfortunately not a well known game... I did end up spending some time in reverse engineering most of the code some time ago.

That Micronics burn!

This was super cool and with the help of the pause button to think about it, it started to make a bit of sense. One question: does the NES draw the whole 240 lines available pre-Vblank? I thought the image was always 224 lines. I guess the PPU has to do SOMETHING on those other lines.

It's hilarious that the NES now has one of the best debuggers I've ever seen

Thank you Chris for making these code breakdowns, especially of MM2 (the first MM series game I ever played/beat... ONLY ON STUPID NORMAL MODE!) Thanks for also showing us about MM3 and the code improvement ROM. I'm am injecting that one into my 3DS right now as I type. :D I know this is WAAAY above anything done so far, but it would be legend if you (or researched and found someone who...) could find and fix the so-called 'Unknown bug' in DK64 that forces the game to crash unless the expansion RAM pack was used in conjunction. Maybe an idea for the future? (Again, NOT expecting cuz DAYUM trying to reverse code DK64 even if it IS still assembly)

❤❤

Wow, that's a lot of code just to find the tile at the current position! And > 10% of a frame is a lot to just move Mega Man horizontally. I imagine vertically should be as costly? What about moving enemies? (Or maybe some of those don't check 3 different collision locations at least?) Given that number, I wonder how it has time to run all the game logic within one frame? (I guess it's not far from the limit, given the Mega Man 3 slowdowns you showed.) Also, I guess that they didn't really have to bank switch between head, body and feet. But those are only 6 bank switches, there seemed to be a lot more of them in the event viewer? Or is each bank switch so many yellow dots that it's only 6 bank switches inside the move horizotally function?

bro i fuckin love recca

Rock&Man.

If you are going to be referencing a previous video, it would be really nice to also provide a link to said video somewhere! It's not a massive hassle, but all the same it *is* a hassle to go looking for it.

Am I the only one who read the title as "Code Wank"? It was so fitting and all...

Very cool! Could you look into mike Tyson’s punchout. You can read! Ive made things happen in that game! Im no master but I’ve done things people haven’t seen and it would be nice to find someone who may me able to look at the code. Here’s a video I have. Sorry I only could record it from the end. Its on my original nes console and I know it is not my” cart is dysfunctional or not in correct spot”.

How could People Claim all the *DECADES* that MM3 was to much for the NES when MM4 Looks arguably even BETTER! Of course it was Bad Coding! Thanks for stating that and other things

I know it's a weird mashup, but I wish you and Kenny Lauderdale could coordinate for bi-monthly releases.

now that i think about it, u should make a video of recca, a game that seems very optimized for once :p

Taco!

Can I grab my peanut butter carrot stick instead? I very much enjoy your videos. Please never get discouraged.

"Or LESS: See Micronics" Hah!

What software would Nintendo use in 1985.....or would it just be numbers on a page?

Why do postfix sub to the name of some subroutines?

0:47 "megaman handler" or "megamandler"

8909, it's x-position, it has to go somewhere.

How did you know tacos were my favorite beverage? Uncanny

I hate when people say "they should've just put less stuff onscreen". If they did that they would have to place pits and walls all over the place just to prevent stuff from being on the screen at the same time.

Can you do a video on the megaman for gameboy one day?

Very nice video. I will not knock the programmers. This stuff is horrendously complicated.

What's a typewriter? (Kidding...)

Is it just me or does this guy sound similar to Josh from Let's Game it Out

Heh, If MM3 lags on an NES, I wonder what causes the Mega Drive Wily Wars to lag on a much more powerful system. I guess that's also some far from ideal code, as there is no bankswitching in that game.

water gang

My teenager recently: "If you liked Atari so much, why didn't you just do coding in college?" Thanks, public schools.

Chris/hackers: "MM3 is NOT too much for the NES" Also Chris/hackers: "MM3 needed double the storage affordable for the time to run well" Wily Wars: *still a massive slug of a game that makes the Genesis look like a dog, at least until it got its own, official hacking*

Second view!