Code Walk! CPU Cycles and Performance of Mega Man 2 (Bonus: MM3) - Talkin' Code Ep. 4
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- Опубліковано 25 чер 2024
- Code walk of a Mega Man 2 subroutine with cycle counting, execution time as a frame percentage, and improving Mega Man 3.
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0:00 Intro
0:41 Code Walk
14:13 The Math (Percentage of Frame)
17:54 Marked Breakpoints
24:26 Mega Man 3 Performance
27:19 Outro
#NES #MegaMan #Programming - Ігри
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.
good god that really long section over the pit, when you didn't have rush jet filled up and had to do it manually... the worst.
No kidding, thank God for Magnet Beam, Item and Rush Jet for those long corridors filled with these fucking blocks!
Been my enemy since 88!
@@Waifu4Life Validates yet also kinda defeats the point of the stage select.
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!
$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.
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.
Admittedly, I have thought about a Displaced Gamers t-shirt related to a taco, a beverage, and a code walk. We’ll see.
What if tacos aren't my favorite beverage?
@@DisplacedGamers I would buy!
I didn't have a taco, so I grabbed leftover noodles instead. Am I doing it right?
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.
18:55 We know what typewriter is, we are not that young :)
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.
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!
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.
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.
Wow, spartonberry. That's crazy!
While I haven't looked at a whole lot of SFC/SNES stuff (yet), my impression is that many developers didn't use the hardware... well... "properly" (for lack of a better word). Sometimes it seems like they took a brute force assembly approach to it without paying the same amount of attention to speed/DMA/RAM. Of course, there is also the issue of SlowROM/FastROM, etc.
Have you had your hands in any other SFC games that use DMA in a way like that that doesn't quite make sense?
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.
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 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!
Thanks. Yeah - I feel like whatever 32k was loaded for the FDS disk version in that area just wasn't split into banks in a way that was friendly when it came to accessing the part of the map along with the usual player input, etc.
I just started developing NES games, so this is the best channel I could have found right now. Amazing work, man. Amazing.
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.
I agree, but I hate how much the buster needs to be used in that game since it whirs over the beautiful music. At least in 5, it won't if you like, land on the ground right when it starts charging. Megaman 5 might be my favorite in the series overall.
@@Valientlink Need to use buster is not as big as you think. Mega Man 4 boss weapons are actually quite fun to use and quite balanced.
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
exactly, the 80's dev would be salivating over these tools
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.
I felt the same way. That 2nd half of Needle Man's stage is the worst design in the whole series IMO. If you run out of rush jet and grabbed all the refills along the way that you need to make the big gap, you're forced to just use up all your lives. I had to do that over and over and it was so frustrating.
It's too bad Megaman 4 had to ruin the rush items, but in fairness rush jet was super abuseable, it's just terrible the way it works from there on.
Megaman 3 was the first game in the series I played. When I went back and did 2 later, I was amazed at how much smoother it was, even without the slide. Then I played MM1 and was even MORE appreciative of how good 2 was.
@@TheWizardOfJim Pretty much the same for me. First 3, then 2, but then I went on to X and Legends lol
@@Valientlink It makes me wonder whether they once meant to make it like MegaMan 1, where placed items regenerated when you returned, or if Rush was ever meant to be unlimited, as someone once speculated over some actual soft-locks you can get into where you can't jump high enough to escape the area if you're out of Rush energy. I guess the other possibility is they meant for you to use the "doesn't consume energy while jumping" exploit and/or farming enemies you encounter on the little islands along the way somehow...
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 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.
Now go watch some of the videos from 3B1B and Reducible about how the algorithms behind JPEG, MPEG, and MP3 work. It's insane.
Computers ARE NOT faster than us
I dont think you realize everything your brain is doing
And on top of that how efficient it is using very little wattage and producing little heat while
The computer you typed that on isnt even faster
Our brains are quantum
Just sit there and think about everything goin on in your body while also controlling it in this world
On top of that the ridiculous amount of storage it has
So just fyi the fastest computers on earth are no where close to the speed of your brain all while using 20watts and it can make itself faster when needed
Yes, I mean modern processors can run in the range of teraflops, meaning over a trillion floating point operations per second. Imagine doing a trillion of anything in your entire life.
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!
Love this series of videos! Keep it up!
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
This is one of the best videos I've ever watched on youtube.
I'm always amazed at the depth of your work. Kudos!
You can dedicate all future videos to mega man and I for one would not be disappointed :)
Love the code walk - been trying to make a Megaman game myself !
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
*DRNT*
*DUH NR NR NRNT*
*DUH NR NR NRNT*
*DUH NR NR NRNT*
*WHRR WHRR*
RE
SPECT
CODE WALK
ARE YOU TALKIN CODE TO ME?
ARE YOU TALKIN CODE TO ME?
rip dimebag 4/20
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!
Another fantastic video =D
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
No worries: the guy who figured out ACE (and thus the Credits Warp, the one were you put in Ocarina of Time to set certain memory values and then quickly switch cartridges) on Paper Mario had no prior experience in programming.
ua-cam.com/video/O9dTmzRAL_4/v-deo.html
All the little bank switches flying by is like a sandstorm
The Micronics burn was the icing on the cake of this delicious dive into the performance of Mega Man 2. Thanks!
Can't wait until you tackle Back To The Future NES and why the music is double-tempo compared to what it should be!
you mean it's not just incompetent composition???
@@SmeddyTooBestChannel I'm pretty sure they just fucked up somewhere while importing it into the game and had already run out of time
I always assumed they didn’t get the rights, stripped down what they had, and sped it up to fly under the radar - or because that was considered enough to not get into legal trouble with the label.
@@DisplacedGamers LJN under Acclaim I think had enough pull in the 80s to shell out like $500 (was cheaper back before CDs and MP3s) for the rights. If that was the case though, it would've made more sense just to use any other track than one that sounded absolutely insane. Gotta be a bug.
@@geovani60624 So THAT's what that license plate meant on the Delorean!! -- It was referencing the NES game adaptation!
(For those who never looked closely -- the license plate says "OUTATIME" -- lol)
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.
Naice! I dabbled a bit with the GameShark on PSX when they first came out with the printer plugin port for GS.
@@DaWhiteTyger oh yeah, they did have a Parallel / serial port on them.
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'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!
Ow, my favorite video type!
Always thought Mega Man 3 was off, always had to use a fan patch to enjoy it.
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.)
never have a clue what youre ever talking about. but i love listening
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!
That optimized megaman 3 looks so good! I need more info! (and a flashcart lol)
It's hilarious that the NES now has one of the best debuggers I've ever seen
That Micronics burn!
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.
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.
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.
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
Thanks!
Thank you!
@@DisplacedGamers You're welcome, love your content
Am I the only one who read the title as "Code Wank"? It was so fitting and all...
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)
Thanks, TheWhite Tyger.
Honestly, it would be fun to have a whole team of people interested in putting together content so the research/reversing endeavors could be separate from the scripting/presentation! I just have to crank out things as fast as I can.
I haven't read much about the DK64 bug in the past, but I want to say it was a garbage collection problem? Like there is a slow memory leak that doesn't reclaim RAM on the system, and the expansion RAM basically extended the crash time long enough to where it is unlikely to happen? I may not be remembering it correctly.
@@DisplacedGamers Could you do an analysis of Rygar PAL version? Due to some bug or limitation it is much harder to finish than the NTSC version, as you are level capped much lower.
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?
Can I grab my peanut butter carrot stick instead?
I very much enjoy your videos. Please never get discouraged.
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.
There should have been a card that popped up in the appropriate moment of the video.
@@DisplacedGamers I'm afraid I have to inform you that no such thing showed up for me. I hope they're not phasing out yet another feature.
bro i fuckin love recca
❤❤
I know it's a weird mashup, but I wish you and Kenny Lauderdale could coordinate for bi-monthly releases.
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.
"Or LESS: See Micronics" Hah!
now that i think about it, u should make a video of recca, a game that seems very optimized for once :p
Rock&Man.
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”.
ua-cam.com/video/YKcf8Ecm6kA/v-deo.html
Taco!
How did you know tacos were my favorite beverage? Uncanny
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?
Very nice video. I will not knock the programmers. This stuff is horrendously complicated.
What's a typewriter?
(Kidding...)
0:47 "megaman handler" or "megamandler"
8909, it's x-position, it has to go somewhere.
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.
My teenager recently: "If you liked Atari so much, why didn't you just do coding in college?" Thanks, public schools.
Can you do a video on the megaman for gameboy one day?
Anything specific you would like to know?
@@DisplacedGamers what about how the movement and collision code is handled
@@DisplacedGamers Having recently acquired Megaman II for the gameboy, the hit detection when it comes from using your base weapon, feels off compared to the Megaman games on the NES. I feel like when Megaman shoots on the gameboy version, there is a several pixel area in front of his arm cannon that is simply dead space, where there is a bullet there, but it won't affect anything until it travels X pixels forward first. I don't know a better way to describe this unfortunately, although I do feel it's also more apparent due to how crammed the screen is on the gameboy.
Is it just me or does this guy sound similar to Josh from Let's Game it Out
water gang
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!