Hardware Registers - Super Nintendo Entertainment System Features Pt. 11

[@jimmerjammy]

This series taught me a lot about old hardware design and coding. These are possibly the best videos on hardware I’ve ever seen!

[@omegarugal9283]

these are quality videos,not the crap tha ytuve is full off

[@MrGlowstoneMan]

um jammer lammy

[@willful759]

This series taught me way, way more about how computers work than my uni classes

[@JustWasted3HoursHere]

When RAM is expensive and clockspeeds are relatively low those systems used some really clever approaches to get things done, and that's what gives them personality. Each system used a different set of approaches to accomplish things and as such they end up having a certain "look" to them. It's easy to spot a Commodore 64 game just by looking at it, just like the old Atari systems, ZX Spectrums and so on. Newer consoles are all so evenly powered that they start to look the same and differ only in what games have been developed for them. I think this is what people miss about those old retro systems.

[@brettito]

You should check out Ben Eater.

[@theMoporter]

You lost me like 7 parts ago but I still watch all of them

[@oafkad]

"Yes, yes, registers. I remember using those in retail. Go on."

[@glubtier]

It's just so nice to listen to...

[@djmoch1001]

His voice is very soothing, even though I'm completely lost on the subject matter. I have been following it though, as the SNES has been a part of my life since I was a kid and never really understood how it worked on a technical level. It's just a bit beyond my comprehension.

[@accuratejaney8140]

I couldn't write it in assembly or C++, but I could probably summarise it or ace a quiz if I were to rewatch the series

[@roelbrook7559]

"This is the last episode of unit 1." Can't wait for unit 2. These videos are amazing.

[@TheMoney9999]

"as the last chapter of the first unit" THE FIRST UNIT???????

[@Smileyrat]

Hope you are ready for the test.

[@SanctusDeAnteurbani]

It was all in the syllabus.

[@ohnoitschris]

The absolute unit

[@vinesthemonkey]

this WILL be on the test.

[@moosemaimer]

I hope you all remembered to pay your lab fees and pick up a copy of the workbook.

[@andrejwalilko634]

saddest 4 words in history: "part 11 of 11"

[@solhsa]

happiest 2 words in history: "appendix 1"

[@Gamezopher]

Well, I couldn't wait for the end of it after nearly five years! I never expected this series to become so long, but of course I understand the hard work behind it.

[@Tanka036]

Im more excited about "first unit"

[@TroyBlackford]

I'm so grateful to you for this channel. It's just fascinating. I'm in no danger of being able to program an SNES game, but I really appreciate being able to glean a better understanding of how my favorite system works.

[@duccie]

"this video will be more of a reference than an explanation" still watches the full vid

[@ShimmeringSpectrum]

This series was better than the 400 level course I had to take on computer hardware architecture as part of a computer science degree. You're fantastic at explaining these things in just the right amount of detail for folks with a background familiarity in how computer hardware works.

[@jmhecker]

I think I can safely say that this is by far the longest running series of videos that I have watched. 4 years since the first video, and I have watched each of them the day they go out. Well done sir, well done.

[@shinyhappyrem8728]

There's also Freeman's Mind (2013-2020), and SovietWomble's videos

[@LittleMissJenn]

Not going to lie, despite playing way too many games in my life, I know nothing about code, software, hardware, computers, gaming systems, etc. but I have watched every one of your videos and found them so informative and comprehensive and I’m kinda sad this series is ending because it’s so interesting!

[@skimmilkm]

So you know 50% of all you need to know to write an NES emulator. You already made it this far!

[@Smileyrat]

he said this is unit one, implying that there will be more.

[@LittleMissJenn]

@@skimmilkm as a music teacher, I don’t know how helpful that will be 😂 haha

[@LittleMissJenn]

@@Smileyrat good point! You’ve got my hopes back up!

[@sundhaug92]

@@LittleMissJenn there are musical programming languages, which can be used in live performances and work with samples

[@xylexrayne8576]

This videos have taught me more about my favorite console than I could have ever asked for. I feel like someone could totally make a game today, using these videos as a powerful reference.

[@adam850]

Very comprehensive. Thanks for making this. I am curious about that expansion port and if it is possible to hack in a helper PPU.

[@skkeye7438]

I wonder if it could be possible to make a custom expansion port ethernet adapter and a custom cartridge with a custom browser...

[@shinyhappyrem8728]

IIRC bsnes has an option to enable 128KB of VRAM (you have to recompile from source), but it's only useful for homebrew games. It also breaks at least some commercial titles.

[@mrflamewars]

I hope there is a video about add on chips in the cartridge, particularly the Super FX and how it draws to the SNES screen. Please.

[@hicknopunk]

And how it texture maps polys

[@awanderer5446]

@@hicknopunk The only hardware feature of the Super FX that's directly related to rendering graphics is the PLOT instruction, which draws a single pixel to a buffer. Apart from that, it's basically software rendering, so texture mapping is completely up the programmer, it's not a feature of the chip.

[@hicknopunk]

@@awanderer5446 I'm not doubting you, is there any document on software rendering on the SNES which describes how exactly they texture mapped polys?

[@Techokami]

Now I'm curious to see if someone can actually modify a SNES to have the extra 64K of VRAM... Also, I'd love to see you tackle either the Game Boy, Genesis/Mega Drive, or Game Gear next!

[@onffxiimanon]

When I saw new parts of this series show up in my feed it ALWAYS caused an audible *GASP*. So sad to see it end. :(

[@dancinninja]

It's always a good day when a new RGME video hits! Thank you for putting the corresponding part number in the corner!

[@thezipcreator]

"Babe wake up, new RGMEx video"

[@mariocamspam72]

"shut up im watching retro game mechanics explained snes"

[@dogg-paws]

To think early video games had to be developed with assembly code... talk about pain.

[@awanderer5446]

I can be fun. Probably not with tight deadlines looming and limited debugging capabilities that developers back in the day had to endure, though...

[@bluesillybeard]

I believe C was invented before Nintendo even existed, though assembly was still very popular.

[@daandroid614]

i just now turned on my computer and opened youtube, what great timing

[@seafarerpixel9860]

I am getting into developing/hacking on the SNES and I've been trying to get down all the documentation I need before I do a good disassembly of a game. I was trying to document all the hardware registers using YOSHI's doc and the wiki, having trouble putting everything down with complete tidiness and certainty when I remembered you recently uploaded this video on the registers, and it has been all I have needed. Like seriously, all my notes are perfect because of how this video is up to date and completely well-sorted. Now I'm looking forward to getting my head around that damned SPC700, too! Really, you're the reason I got into this SNES hacking in the first place. I watched your series in high school and got inspired by how everything worked and how assembly was coded and how memory was mapped and what sort of glitches would leak through, that the following summer I dipped into NES development. And a year or two later, when I had just finished my second playthrough of A Link to the Past, when I wanted something to preserve the magic that the difficulty first created, I don't know if I would have considered myself to potentially be the one who should design that Master Quest. And now I'm deeply fascinated with the idea of developing for old consoles and hardware. It's just… free education, which is something great to have in the world. Because, you know, good novel education nurtures creativity and interest. And, damn, I didn't intend to write so this elaborate extent, but hey, it's just to say thank you, RGMechEx, you're doing a fantastic job with these videos.

[@coleeau]

thanks for making these videos, i really enjoy learning about hardware and this series has been extremely helpful for that!

[@cst1229]

There's now an audio track feature in youtube i think. Just saying because I remember RGME saying that he would add music if there was an audio tracks feature.

[@CarbonRollerCaco]

… Wow. This makes me realize how unique of an operating environment each of the old systems were. Every hardware configuration is a computing engine in itself, with the software being sub-engines made for or adapted to the hardware. And the SNES in particular seemed to make REALLY good use of memory. If there's anything modern computing could use more of, it's memory conservation.

[@AgentM124]

I literally watch this to listen to all the satisfying hardware terms. And him saying hex FFFF

[@johneygd]

Wow it sounds all very complicated but still interesting at the same time,it’s just incredible how those engineers from nintendo did figure out at what’s necessary,needed and what not while still being forward thinking and keep the whole system within a cheap price range for the consumer,if the snes was just designed with games such as supermarioworld in mind,well that explains alot.

[@rayredondo8160]

Perfect to watch while preparing to reinstall Gentoo! 🤣 Great videos as always, can't wait for 6b and whatever else is next!

[@BlitzWhat]

Nothing makes me enjoy feeling like an absolute brainlet quite like these videos.

[@onlysilv]

I'm calling someone a brainlet tomorrow

[@djmoch1001]

Meanwhile I feel like an utter moron for not understanding it at all. Despite that, I'm finding it fascinating. His videos are so well presented, and his animations and stuff are brilliant. I just wish I had a better capability at understanding the subject matter.

[@bitsaucetv]

To think I’ve been watching this series for over a year and...a half...crazy

[@plushifoxed]

uooooh, we're finally at the end of the series! nice work!

[@genesis_ink]

mf's be listening to lofi or asmr to relax, i be watchin this shit bro

[@Crankthatsnes]

Here I go getting excited about 30 year old computer chips again

[@andrewsprojectsinnovations6352]

Dude the SNES and Genesis have the perfect balance in my opinion: powerful enough to be fun to play 30 years later, but still weak enough to provide some challenge for the developers. As a young programmer I sometimes feel like I have it too easy with gigahertz clock speeds, powerful GPU's (even the low-end integrated ones), and several gigabytes of RAM at my fingertips....

[@benox50]

@@andrewsprojectsinnovations6352 Not a coder but agree, the puzzle solving and unique workflow is greatz, I also think NES is just too limited and this is where it really started to get a good working base, we can still find uses of its legacy today like the additional blending of layers.

[@Kj16V]

Love these videos. I understand about 10% of it, and forget even that almost directly after the video, but I still love 'em!

[@SECONDQUEST]

Thanks dude. While I'm not employed or otherwise involved with anything like this but I've very interested in learning how things around me work, and how math can turn into graphics.

[@glitchy_weasel]

Amazing series overall! Any plans of covering more retro game consoles in the future?

[@Bry10022]

Then N64 stuff explained…

[@mariocamspam72]

why

[@davidmcgill1000]

@@mariocamspam72 An explanation of the N64 microcode would be interesting. Wouldn't expect the CPU to be all that unique regarding MIPS.

[@GeneralBolas]

Honestly, I'd love a Sega Saturn explained series. I've always wondered why it was so legendarily hard to program for, and the most I've gotten was "it had two CPUs and a separate graphics chip". This doesn't really tell me much. And I know that multi-processing was in its infancy in those days compared to now, but I'd really love to know what *exactly* was going on that was so hard to deal with.

[@Jabjabs]

@@GeneralBolas It would actually make a great addition to this series. The dual graphics chips are fairly interesting mostly in that the 3D GPU uses quads which can essentially just be seen as being really complex 2D sprite manipulation. A big issue with those was the immense calculation time needed to do a single quad transform. It took the Saturn CPU's 28 cycle to do a single transform, compare this with 13 cycles for a polygon transform on the PS1 and you start to get an idea of the issues. The second GPU is used only for 2D assets but is used in a fashion kind of similar to SNES Mode 7. An excellent example of it in action is with the Panzer dragon games in that the scrolling ground on all levels is merely a 2D object being manipulated as a background layer. The dual CPU's aren't too amazing except for their 16bit dual instruction issuing in which two 16bit instructions could be issued per a single 32bit instruction, a neat trick of the SH2 chips. The SCU chip with its 6 way instruction issuing for use with Matrix transforms would be very interesting but I think the channel Coding Secrets has already covered that fairly well. An interesting system to cover but not sure if there would be much new to learn from it.

[@stevedi]

1:31 I'm just imagining the effort that went into organizing this info

[@RGMechEx]

About an hour of scribbling on a white board!

[@TheBrandon164]

It would be cool to know how Special GBC Cartridges work. Like Kirby Tilt 'n' Tumble and Pokemon Pinball

[@MegamanXGold]

Your videos rock! I'm just wondering, Vitor Vilela is planning to make some videos, is there any opportunity for a collaboration there? Or maybe just a cross promotion of some kind?

[@oskarkamil8208]

I have no idea what you are talking about and I don't know anything about computer registry. But I will still watch it :D

[@andrewjvaughan]

Man, you really thought out this series.

[@markganus1085]

the 5 stages of the instructions pipeline in RISC processors: IF: Instruction fetch. ID: Instruction decode, register fetch. EX: Execution. MEM: Memory access. WB: Register write back.

[@InsaneFirebat]

This stuff is so much easier to follow now that I've started digging into romhacking. Thank you for these awesome videos!

[@InsaneFirebat]

You saved me again. Thanks!

[@RiVaLBrite]

I LOVE these videos! Please never stop making them.

[@theemeraldboat9947]

you are one of the best creators on the platform!!!!!!!!!!!!!!!!!!!!!!!!

[@NoLongerBreathedIn]

10:41 although note that when looking at the tile to the right, on original hardware this does not carry to the high nybble if the tile ID ends in F. Emulators vary.

[@masterinsan0]

Hey, just wanted to say: I absolutely love these videos. I think I've watched every single video on your channel at this point. Your production values are top notch, even the audio which has steadily gotten better over time. However, there's still one problem with your audio that I think would drastically improve the watching experience: getting rid of the audio clipping caused by plosives in your speech. Just add a pop filter to block the loud "P" sounds and it'll be basically perfect!

[@default4561]

Awesome video! May I ask with which program you created the graphics and animations?

[@RGMechEx]

After Effects!

[@MadameSomnambule]

These vids: Goes into an amazing amount of detail about assembly language in retro consoles My brain: Write that down! WRITE THAT DOWN!!

[@jojodi]

Congratulations :) Looking forward SPC series :D

[@Nikku4211]

If only there were homebrew expansions that used the external sync from INISET... Hey Azavier, what's the first 2 hexadecimal digits for PPU registers on the SNES?

[@flo-plus]

You saved my day:)

[@thecunninlynguist]

Love these dives into hardware

[@Ryan-zp4qo]

One thing that still puzzles me is the idea of "writing twice" to any given register. What is the purpose of writing a byte somewhere, just to immediately overwrite it? Is there a practical reason to do this, or is the procedure associated with it something else completely?

[@RGMechEx]

Internally, it's a 16-bit register and flip-flop, mapped to an 8-bit memory location. So the first time you write to it, you write to the lower half of the register, the flip-flop switches over, and the second time you write to the upper half. It is odd though that there is a mix between both write-twice and the more intuitive pairs of 8-bit registers though.

[@vuurniacsquarewave5091]

Even the NES PPU has a bit of flip-flop logic like this. Its VRAM address has to be set up in a similar double-write manner, and by extension the screen X and Y coordinates share the same flip-flop. You can even do something like "Write the high byte of the address, then write the Y coordinate immediately". So it's good practice to either keep track of which state that flip-flop is in or reset in manually with a read of the status register before doing your thing.

[@Ryan-zp4qo]

@@RGMechEx @VuurniacSquarewave Ah, makes sense. There's probably some compatibility or cost concerns in effect - 16 bit CPU and PPU, 16 bit registers, no fumbling with "is this x-bit or y-bit logic". Excellent replies btw, it's great to see technical minds converge.

[@kargaroc386]

Magic memory locations that perform multiplication/division like its the 1960s the Apollo guidance computer does this except its for bit shifting

[@sosasees]

i don't understand these infos enough to use them. i now have more respect for makers of 16-bit and earlier video games. even though i realized that making games for old systems will never be for me, i also got some very useful ideas for my modern computer games that i would not have had if i didn't watch your videos*. * the bitplanes thing made me want to split my sprites in a similar way so that i can not only put different colors on each part, but also different shaders (which would be the 2d equivalent of putting different "materials" on different parts of a 3d model). and i will also want to purpose an array as a stack in an especially RNG-heavy game to pull pre-generated random numbers, so that not nearly as many of them have to be generated at once, which saves performance.

[@Wyattporter]

First unit?!

[@cy-bernet-ix]

i dont understand any of the technical terms but i get the gist of it and thats what counts :3

[@hicknopunk]

Please do a video explaining texture mapping on the SNES. I always wondered how games like Vortex did this.

[@duncathan_salt]

I've been waiting for so long!!! I'm so excited

[@gabrote42]

Not SummoningSalt but still something we all waited for

[@n2n8sda]

Yay been waiting for this!

[@willarasmith4893]

Me: I have no idea what any of this means. Also me: watches the whole video acting like I know what everything means.

[@sa3270]

RIP Masayuki Eumura, creator of the NES and SNES.

[@Tonithemeloni04]

Not knowledgeable on these types of subjects but they’re still cool

[@mousejuggler9331]

This is magical.

[@stahlkiefer]

Really good and informative. Like your videos. :)

[@mypkamax]

Can you make a video on Vib-Ribbon's custom music level generation algorithm? (You can insert a music CD while the game is running and play a level based on the inserted music)

[@romajimamulo]

... wait, first unit?

[@RGMechEx]

The SPC700 and Cartridge Enhancement Chips series are going to be regarded as Units 2 and 3 most likely!

[@roberte2945]

@@RGMechEx Hooray!

[@jonathanfaber3291]

The legend returns!

[@VashStarwind]

Hey man do you think you could make a video about the exact programs, and hardware, that they used to create snes games? Like what programs/software did they used to create the sprites and/or backgrounds, and what kind of computers they used. I have been trying to find information on this, but it hasnt been very easy. And if you already have a video on this subject, could you, or someone, please let me know what video it is, or any video for that matter. I have been wanting to watch an actual documentary of the SNES game making process, to kinda learn what programs and computers, and also hardware used to make the songs with, but cant really find anything like that.

[@graythomas6420]

Your videos are amazing!

[@jacobd.6143]

I was wondering if you could thoroughly give people an answer to these glitches my brother found on his NES Classic Edition system: In Balloon Fight, if you hug the right edge of the screen in Balloon Trip mode, then the piranha will never appear, no matter how long you float in/near the water. In Bubble Bobble, the password DEDDD will take you to round F9, which apparently a Super Drunk bossfight, like any round after B3. Some passwords, like this one, will give you a bad ending when you complete the bossfight. Others can give you a good ending if you have a second player spawned in, which can be done in 1P mode by pausing and pressing SELECT, unless you have no spare lives left. In Castlevania II: Simon's Quest, you can occasionally pause and glitch the colors of the pause menu/map, which can be fixed by pausing over the glitches colors. Sometimes, half of a set of blocks get deleted somehow, and by either whipping or throwing holy water on the ground with precise timing when you fall, you can fall through the ground and potentially into invisible water. In Donkey Kong Jr, after dropping both fruits in the final stage somewhere in between the 5th and 15th level (he forgot where exactly), the game lags for a few frames and stray 0s show up on the top of the screen. In Excitebike, driving off an upwards slope, tilting forward, then leaning back as you hit a ramp can send the bike flying upwards, sometimes so high that it wraps around to the bottom of the screen before falling back down. In Ice Climber, if you jump on the first frame you hit a platform, you jump again, bypassing the collision for the platform above. In Kid Icarus, my brother found this out about passwords: Increasing the 23rd value by 1 and the 24th value by 4, you get another password as follows: title screen, start/continue screen, 1-x, where x is a common variable that will crash if it is not 1, 2, or 3, 1-4, 2-x, 2-4, 3-x, 3-4, 4-1, ending. If you go beyond the ending, the game will also crash. Some of these crashes are detected by the system and bring up an error message, then return you to the main menu, others do not. You can type 24 of 0s, Ls, gs, or !s, each of which has a value of 21 higher, to get another working password. Typing 24 vs or 24 !s will cause a crash, so use the rule above in reverse to prevent this. The weirdest crash occurs if you load 2-0 using the password !!!!!! !!!!!! !!!!!! !!!!qJ. Loading the 4th level as a non-dungeon level will also crash the game. You can also count the number of values from 0 an individual password has and then replace all values with ones of the same distance from ! and get another working password. Use the first rule as necessary to avoid crashing by not loading normal stages with a value of 0 or 4-255. Another important rule: If you increase the 22nd value by 4 and the 23rd value by 16, it will increment the sub-stage number by 1. I'm a bit fuzzy on this one, but I think if you increase the 22nd value by 1 and the 24th value by 4, it will increase your strength level by 1. I might be incorrect here, as it has been a while. In Metroid, you can cause a variety of glitches effects and even crash the game with the password 210 -L KJIHGF EDCBA9 876543. If it does not crash, it will return you to the title screen. Passwords such as edcbaZ YXWVUT SRQnml kjihgf will also return you to the title screen but will crash if ERROR TRY AGAIN is displayed on the screen. In Super Mario Bros, the maximum number of lives you can get without getting a GAME OVER is 129, but you can also cause an overflow and get 0 lives, displayed as x0. You can also execute the over-the-Goal-Pole glitch in 1-1, 3-1, and 3-3. Super Mario Bros. 2, if you throw an enemy into the ground just as the stopwatch times out, it will become trapped in the ground. If it is under a ladder, you can jump and press B when you land to attempt to pick it up. If you do, you can press down on the D-pad to warp to another location. In 3-1, this will be 3-[], a glitches version of 1-2. You immediately move on to the next stage after clearing it, and fight the harder variant of Mouser at the end, which will return you to the vine at the top of the vertical section of 3-1. If you enter a Hawkdoor while holding an item, you can pause the game and press up, B, and A simultaneously on the second controller to cause the held item to drop, but you will take no damage. You can press the button combination again to actually die. In this event, the death animation will finish once you start the next level. In 1-2, if you get the flying carpet, fly under the ground, not flying too low so that you don't get stuck off-screen until the carpet timer expires or you fly down to you death. You can then fly up into the ground and quickly alternate left and right to slowly fly up through the ground until the carpet timer expires and you get stuck. The kill-the-Phanto glitch where you hit a key repeatedly with mushroom blocks until it plays an "oof" sound will not actually kill the Phanto, it just gets very far away. If you hit the key enough, it actually returns to normal until you hit it quite a few more times. You can kill the Phanto by running into it while both a star and stopwatch are active. In the vertical section of 1-1, if you fall off the vine at the bottom and grab it again as you fall off the screen, you will be softlocked until you use the up+B+A trick to die. If you unpause at the right time, it will immediately move on to the screen that displays your remaining lives. If not, you will have to wait about 5 minutes before anything happens. In Super Mario Bros. 3, you can clip into and enter incorrectly any warp pipe with an exposed right side, including airship pipes. In 4-Fortress 2, in the backwards-C-shaped section, you can clip into the lower pipe and be taken into the 17th screen. Standing on a certain tile just off to the right will give you infinite coins until either the timer runs out or you pause. If you paused, just jump or walk off and onto the tile again. Since you may be invisible here, if you are, you will have to wait about 5 minutes to resume gameplay if you die. There is also a pipe hidden above that will take you to the card, softlocking the game once collected unless you have a warp whistle. You can also use the first downward-facing pipe to go down to an area below the start but above the 16th screen. If you are Small Mario, you can enter another pipe below that takes over 10 minutes to reach the end of. (By the way, which takes longer, this or Yellow MissingNo's "true cry"?) There is also another area just below this one that has consistently-changing blocks you can hit, if you manage to get lucky enough for this to happen, since also, there are very many possible places to be dropped from glitch pipes, but the ones aforementioned are the most common. These tiles can occasionally act like warp pipes. My brother found 3 rooms: An underground area with glitched graphics where you fall to your death, another exit area, and an empty castle area with the World 5 fortress texture and a single line of ground at the very bottom, where you are stuck until the timer expires. In 7-1, in the credits warp area, there is a pipe next to where you are dropped that seems to place you in the ground above the screen, where you are trapped until the timer expires. Also, while unpaused, the status bar is moved all the way up near the top of the screen and glitched graphics appear under it. It appears normal only when paused. In The Legend of Zelda, you can press perpendicular direction for 1 frame when 5 pixels from the edge of the screen to then walk through one end and across to the other. If you move back in the other direction after fully crossing, you will then move to the next screen in that direction. If you move left in the top-left corner or right in the bottom-right corner, the game will fade in again and place you at the cave where you get the first sword. In Zelda II: The Adventure of Link, if you jump up to the status bar at the top or higher, and cast FAIRY while in a town, it will make you fall into a version of the left screen of Rauru with the current town's NPCs and all doors leading back to the same place. Only in Rauru and Saria is the second door accessible. You can enter any doors 10 times before being sent out-of-bounds where you will fall back into the town and the glitching stops. You can cast FAIRY on the first possible frame in order to enter the door more times. After the 16th entry, you are placed back on solid ground. After 20 entries, once Link touches a fairy or casts a spell other than FAIRY, he will have a blue outline. After 40 entries, in this scenario, he will appear almost completely gray. My brother only managed to have this happen once, but after 60 entries, Link gets a ruby-red color in this situation. Also, the game freezes if you leave the screen on the same frame that the level-up menu appears. Can you look into these topics and make a video (or series of videos) about the information in this comment? Thanks for looking at this comment!

[@CoobyPls]

Literally never heard "PP" so many times in a video. Fine work.

[@CoobyPls]

This actually is very informative, thank you. I've just got the humor of a 7th Grader.

[@YellowBunny]

20:32 Why does the remainder have more bits than the divisor? Shouldn't the top 8 bits always be 0 after a division by anything but 0?

[@RGMechEx]

The upper byte may always end up zero, yes. This just ensures that it is safe to read the remainder registers as a single 16-bit word, and you don't have to worry about masking away the top 8 bits.

[@Nicholas_Steel]

It would be welcome if you'd edit the Table of Contents/other videos in the series, in to the Description of all the other videos in this series. So it's easier to jump around between videos.

[@seafarerpixel9860]

I believe I have spotted an error. You forgot to include $211A in your hardware register map at the beginning.

[@ErivandoAndrade]

Thanks!

[@johnathanmurray4777]

Not gunna lie, I have enjoyed Retro Game Mechanics Explained but this episode was as dry as reading directly from a datasheet. Need more application, skipped through most of the episode. Maybe someone else really enjoyed this episode but I really prefer the videos where you explain practical examples and phenomena, stepping through code and registers with additional diagrams to flesh out the explanations. This was just a dry reading of registers. Audible for datasheets.

[@ost2life]

TBF he did say it was a reference rather than a video in it's own right

[@kasugaryuichi9767]

Assembly basics next? :3

[@jennasloan396]

Why do some of the patreons in the video description appear as a bunch of question marks? Could it be related to the character encoding?

[@quinnencrawford9707]

how does the earthbound font have it's kemming done?

[@jennasloan396]

Mmm... delicious hardware registers

[@DerAlfredman]

wow the export compression is really visible, still amazing video as always :-)

[@fernandossmm]

I think KZbin does a faster, more lossy compression when uploading, only to replace the video later with a better looking/compressed one. Just a hunch tho.

[@DerAlfredman]

@@fernandossmm ok, thank you for the info

[@jameslaumand3686]

I liked to know how beat at GALAGA love that game,stay in middle what’s secret what does the ship reall look like up close I love it

[@AmaroqStarwind]

This makes me want to hack apart an SNES and a Genesis, and stitch their parts together into a frakenconsole

[@canebro1]

"First" unit? More? Yay!!!

[@mariocamspam72]

Nice

[@jodymcdougle8810]

Is there a way to exchange correspondence with a member of this channel's staff? Hoping to find an email address. Also, is there a section of this channel's content to start with? I'm sure that I will come across a lot of areas which I will ask in the comments section, but asking for an email address with questions for questions that may be outside of this uploaded content.

[@djmoch1001]

Fascinating information presented, but waaaaaay beyond my paltry comprehension.

[@ecernosoft3096]

Who else wishes the SNES used a 7.16 mhz 68k instead? It could’ve had a 1.79 mhz 2A03 for backwards compatibility:

[@Deniii4000]

At 3:02, when you mention the priority switch of $2103, you say that one should write the index of the object in the first 7 bits of $2102 and that the value should be between $00 to $7F. As I understand it, the least significant bit (bit 0), kind of toggles between the X/Y position (write twice to $2104) and the character/attributes (again write twice to $2104) of a single object. That is, $00 points to X/Y of Object 0 and $01 is character/attribute of Object 0. Object 1 would be $02 and $03 and so on. What I mean to say is, what should be written to $2102 to select the index of the object, shouldn't it start at $00 to select Object 0 and then increase by $02 until $FE? ($00, $02, $04, $06, $08, $0A, etc. until $FE)

[@RGMechEx]

That's what you would think, but it is indeed just the index. I believe when the highest bit of $2103 is set, it sets up the hardware in such a way that the next write to $2102 is sent somewhere else in the PPU. So it's not really acting as a pointer into OAM.

[@LBXZero]

What about the expansion port on the bottom of the SNES?

[@RGMechEx]

The expansion port basically just exposes some address and data pins that give it read/write access to the entire $21xx page. It's up to the device that plugs into it to listen in for reads and writes to addresses it may be interested in. The addresses from $2184 to $21FF return open bus normally, so these are usable by any device that plugs in here (and also in the cartridge slot, since it has access to these pins as well). For example, the Satellaview used addresses $2188 through $2199. But those aren't "reserved" for the Satellaview, as another device could use those addresses as well, as long as it wasn't connected at the same time a Satellaview was.

[@LBXZero]

@@RGMechEx This makes me wonder how much the SNES-CD project could have added to the SNES, if the terms were better.

[@idkwhy5386]

Now what about NES and N64 Features

[@otesunki]

HES DONE WHAT

[@pp3k07]

This crowd man 🤦‍♂️

[@CiroGalli]

Sorry. I lost you right after "this video..."

[@renakunisaki]

So when's the final exam?

[@lior_haddad]

Hi

[@ricardopurnell3923]

SOINC SPEED

[@higashikatajosuke9324]

hmm yes interesting *understands absolutely nothing*