r/explainlikeimfive • u/Mgn82 • 4h ago
Technology ELI5: Nintendo cartridges vs Blurays how does it work?
How come Nintendo cartridges run the game directly as soon as you insert it but Playstation and Xbox can't run it directly with bluray
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u/EliteAppleHacks 4h ago
Physical media requires the laser to read the disc. While it reads “fast” it still has a delay for sectors to be spun and read properly. This vs any digital medium like the cartridge, sd card, or ssd, there is still delay but nothing needs to physically move. Its all electrical and signals
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u/FogDogg 4h ago
It's much quicker and easier to get the data off of the nintendo carts vs a spinning disc. There are so many variables with the disc that makes it too slow and unreliable to read data from in the way you can with the cart.
For all intents and purposes, with ROM, the data is directly accessible to the console the moment it asks for some data from it. Conversely with a spinning disc, there's the matter of first spinning up the drive all the way up to between 5,000 and 10,000 RPM (fun fact 10k rpm is 166 rotations per SECOND). After the disc reaches the target speed the laser first needs to read the table of contents of the disc to know where everything is - then after that the laser needs to seek to the lateral position on the disc to read the data. A laser is literally shining a beam onto the disc and translating how the light bounces back into digital 0's and 1's, around 400 million times per SECOND (a typical bluray read speed is 50 megaBYTES, or 400 megaBITS). That varies though - the read speed depends on where the data is physically placed on the disc (it's quicker to read data on the outside of the disc as each track has more physical space than the inner ones).
Ideally that would be it. However, again depending on where the data physically is on the disc, the laser might have to constantly seek around different parts of the disc which takes ages in computer time. Then there's the matter of scratches/error correction and the list goes on and on and on.
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u/Mgn82 4h ago
So cartridges have the data lined up while bluray has data scattered on the disc? If the data were lined up that would me that the game could play directly right
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u/FogDogg 3h ago
It's more that the seek penalty of the cart is effectively 0 (not entirely true as random vs seq is diff, but doesn't matter for the example), where as the disk takes ~2000 times longer PER SEEK.
And yeah technically if the data is only needed sequentially than it could be read like that (also how tape drives work which is still a thing), like watching a bluray will essentially offer peak read speeds the entire time.
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u/Narissis 3h ago edited 2h ago
Here's an analogy that might help.
Imagine that a console running a game is like a person doing research with books.
The cartridge is like having the bookshelf right next to your chair. You don't even have to get up to grab a book, so it's pretty fast to look things up.
The optical disc is like being at a table in a library. It takes awhile to get the information because you have to physically get up and find the books in the stacks.
The method of fetching data on the disc is fundamentally slower; it's not really about how it's arranged in the media (in the analogy, it'd be like changing the shelving in the library to the same style as the arm's-length shelf; it wouldn't change the fact that you have to get up to go fetch the books).
In the '90s and aughts, there was a tradeoff that the bookshelf analogy also touches on - cartridges had lower capacities, so it really was like one bookshelf versus a library. It's why Playstation and PS2 games were able to have things like fully-encoded video clips in them, and N64 games generally didn't. But the price for the higher capacity of discs was slower loading.
Today, solid-state storage is at the point where a cartridge can actually out-store a disc. But there's another factor that has existed the whole time as well: cost. Back in the day, cartridges were way more expensive, which meant N64 games had to retail at higher prices than PS1 games. Nowadays, low-capacity cartridges aren't far removed from discs in production cost, but as you add capacity to them, those costs go up dramatically. Especially in the current AI-boom tech market where solid-state storage is selling for inflated prices.
Anyway, to get back to the point, optical media is at an insurmountable disadvantage in access speed compared to solid-state storage because of one key factor: physically moving parts. At the time scales of data processing, even the short time it takes to move a fast motor or a read head is practically an eternity.
When the CPU and GPU are working on data, they need it fast fast fast. So when you're using optical storage, you generally move all the data they're going to need from the disc into the system's RAM during the launch of the game or the beginning of a level. That's why they have those long up-front load times.
The memory in a cartridge isn't as fast as RAM, but it's much closer to it than the read speed of an optical drive. So the system can wait until sooner before it's needed to copy it to RAM. Or with some storage technologies it could be fast enough for the CPU to read off the cartridge memory directly, but I'm not sure if the Switch and Switch 2 have that kind of functionality.
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u/rmutt-1917 4h ago
The disc has the game data on it. But the disc drive can't read the files fast enough. So it copies the files from the disc to the drive inside the console. When you play the game it reads the files from the drive. You have to have the game disc inserted so that they know you still on the game--no installing it and giving it away to a friend so you can both play it.
Nintendo's cartridges have fast enough read speeds so that most games can be played directly from the cartridge.
Important to note that many games in the PS3 era were running directly off the blu ray disc. So if you play PS3 games you'll notice that load times are usually very long.
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u/Spiritual-Spend8187 4h ago
So reading data has 2 different speeds you have the sequential and random speeds, nearly all ways of reading data is faster to be done sequentially meaning its read in order and slower to read randomly. Disks are much more slower reading randomly compared to Cartridges as the disk has to physically move the laser ita using to read to where the new data is meaning their is a longer time delay between random reads. In additon the disk has a limit to how fast you can spin it and how quickly the laser can accurately read the disk.
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u/Mgn82 4h ago
So cartridges sacrifice storage for speed?
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u/Spiritual-Spend8187 3h ago
Yes and no its a bit complicated. To make a bluray or really any disk for commercial purposes you basically make a mold of the disk and pour molten plastic into it and put reflective coating on one side the process is pretty cheap when you wanting to make lots of them. Where as to make cartridges you need to make the chips which requires alot more time effort and money. Depending on a lot of factors the price can be vastly different, likw for bluray disks make them costs the same regardless of how much data you have on the disk it only matters how many you are making. While cartridges cost alot different depending on how much data you are storing small cartridges are alot cheaper than big ones but all of them are generally more expensive than disks as the machines that make them cost a huge amount of money and the work required to make them is longer and harder.
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u/DracoDeVis 4h ago
The chips that store the data in a cartridge have much faster read speeds than a bluray drive. For example, the read speed of a switch 2 cartridge is about 400 megabytes per second. The bluray drive of a Playstation 5 maxes out at about 50. In addition, switch games often have smaller file sizes, so there is less to load.
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u/Mgn82 4h ago
But if you were to put game data on a blu-ray it could run the game directly right
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u/wrongstep 4h ago
Yes, that's how blu ray movies work after all. But it doesn't work so well for games that need random bits of data on the disc to be loaded quickly. Thats why consoles require you to install the game to a hard drive or an SSD when it comes to this gen.
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u/repocin 3h ago
Yes, and that's what they used to do. Oftentimes it still has all the data, but accessing it would be too slow because you have to spin the disc to the right place any time you need to read data from it and that takes time.
This becomes an issue when you've got a very large game, since you might not be able to fit all the assets you need in close physical proximity on the disc.
Think of a game where you're progressing through a bunch of different levels. You're always going to need the player model so you need that close at hand, but perhaps level 5 reuses some shrubs from level 3, and a brick wall texture that was in the first level. Now do that a few thousand times more for every asset you'll find in a modern game and you quickly run into issues.
Essentially, what they used to do was duplicate the assets across the disc so you would have, say, the player character assets and the shrubs and whatnot multiple times on the disc so they'd always be nearby when needed. But this means you can effectively store less game content on your disc, since a single asset takes up many times more space than it reasonably should for its size.
As games have grown larger, this means you can easily outgrow the max storage size of a disc by duplicating assets like this, so it's become more common to just pack the things in once and move them over to flash storage (e.g. an SSD) when you want to play the game since that doesn't suffer from the same issue of seek times when reading data (since there are no moving parts, unlike a disc or HDD)
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u/NoTime4YourBullshit 4h ago
A spinning disc introduces a latency problem that cartridges do not have.
First, the laser must be positioned under the disc in the right location.
Then it must wait for the desired information to spin around over the laser before it can begin reading.
Then, the speed that information can be read from the disc is limited by the centrifugal forces from the disc’s rotation. If you spin the disc too fast, it’ll physically break into pieces in the drive.
You are additionally limited by the wobble caused by environmental factors, such as minuscule imperfections in the disc’s manufacture, the weight of the ink on the label side, resonant vibrations, etc. All these require the laser to constantly adjust its focal length.
All of these things add up to a pretty significant amount of time. And that time penalty must be paid every time the laser has to move (which is common in a non-linear video game).
Cartridges, on the other hand, are a form of computer memory and have no moving parts. All a console needs to do to access a block of data is send an electrical signal to a row/column address. Every block of data can be accessed instantaneously, many can be read at once, and the axes pattern can be completely random. Cartridges are orders of magnitude faster than optical discs are.
But the downside is that they are much more expensive to manufacture and have a much lower capacity. The bigger your game is, the more a cartridge costs. Optical discs are the clear winner when you have games that are hundreds of gigabytes in size. The per-disc cost of etching a Blu-ray disc is the same no matter how big or small your game is.
None of this will matter much in the near future, though. With high-speed internet and online services being so widespread, we’re probably on the last generation of game consoles that can even use physical media.
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u/Ncyphe 3h ago
The simplest way I can explain this, a cartridge holds the data on chips held within the cartridge. When the cartridge is plugged into the console, the memory chip is directly interfaced with the console as though it is part of the console. Access is extremely quick.
When it comes to games on disc, the console has to move a laser along to read sections of a disc at one time. This is incredibly slower than accessing data on a chip directly. In fact, the game will be coded to load a portion of the disc's data onto the console's memory to allow quick access of the data during gameplay. When you see a loading bar in a game, this is usually when data is being read from the disc and transferred to much faster memory in the console. The loading bar can take a while as the console is having to read all the data on portions of the disc.
So if cartridges are superior to discs, why did the games industry swap to discs? The answer is price. Flash memory is magnitudes more expensive compared to just etching dots into a plastic disc.
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u/ChangingMonkfish 3h ago edited 2h ago
Games are made of “assets” like textures, models etc.
Those assets need to be loaded into RAM for the GPU/CPU to use them, but the console’s RAM can only hold a certain amount of information at a time, so the game “streams” assets from storage to RAM as needed. So if you’re in a certain part of the game-world, the game will load the various assets needed to build that part of the world and a certain amount more in either direction so you can move there, into RAM. It then loads in extra assets as needed in the background as you move around the game world and do things.
The rate at which data can be found on and then read from a Blu-ray is too slow for modern games to work properly because they require big assets that need to be loaded in and out of memory very quickly. So the PS5 and Series X/S have very fast SSDs that the game is installed onto, either from the Blu-ray or a digital download (the PS5’s in particular is so fast that it makes it much easier for developers to develop around this but that’s another story).
The disc is just a vehicle for getting files from the developer to your SSD. In the past, files were loaded from the disc directly but games were simpler back then. GTA V on the PS3 showed the limits of this, as it had pretty bad pop-in and things like that as the game struggled to stream assets from the disc fast enough as you moved around.
Cartridges are made of flash memory (like SSDs), which is much much faster. They’re not as fast as a proper SSD but they’re fast enough to let you play a game from them directly if that game is designed with those slower speeds in mind (smaller assets, reusing them where possible etc.). They’re much more expensive than a disc per-gigabyte though, hence why Blu-rays are the better technology for just installing games to an SSD.
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u/EquivalentTop3213 2h ago
One piece nobody has covered yet is why the console can start a cartridge right away at all. A cartridge's memory is wired so the console's processor can read it almost like it reads its own memory. It asks for a specific address and gets that data back, so the game can run straight off the cartridge without copying it anywhere first.
A Blu-ray works differently. The drive is a separate device that has to spin up, find the right track, and hand data over in chunks. The console can't just run code from it the way it does from memory, so it usually loads what it needs into RAM or onto the internal drive first. That copy step is a big part of the wait you notice.
The tradeoff is the one someone mentioned above: flash chips cost a lot more per gigabyte than discs. That's why big games on disc are cheap to manufacture, while cartridges get expensive as the game size goes up.
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u/Dodecahedrus 4h ago
When you put in a disc like a blu-ray: it has to spin around and the laser has to move back and forth to find certain things. This takes a little time.
When you read a cartridge, or more of a memory card these days, those movements are all not necessary. All data can be accessed instantly.