9 ms·

How the SNES Graphics System Works

79 points by grigy 2y ago

skvj 2y ago
excellent SNES PPUs overview, also reading part 2: https://fabiensanglard.net/snes_ppus_why/ https://fabiensanglard.net/snes_ppus_why/
jader201 2y ago
FWIW, this seems to get reposted a lot. I think this is the fourth submission in the past 10 days. Three recent submissions: https://news.ycombinator.com/item?id=41207608 https://news.ycombinator.com/item?id=41207608 (147 points, 8 comments) https://news.ycombinator.com/item?id=41210537 https://news.ycombinator.com/item?id=41210537 (18 points, 2 comments) https://news.ycombinator.com/item?id=41207756 https://news.ycombinator.com/item?id=41207756 (2 points, 0 comments)
- pvg 2y ago
  You can just flag it as a dupe or email hn@ycombinator.com if you think it's misranked.
- deleted 2y ago
  [deleted]
- 0xEF 2y ago
  I don't mind reposts now and then, since the odds of two people independently finding the same link interesting over time are pretty good, given the way things tend to circulate on social media and other aggregate platforms. I also worry that HN is slowly turning into a karma farm like Reddit did. The point of reposting on HN just to build Internet Points escapes me,. At least on Reddit there was a market for accounts with high karma, so I guess I could see the motivation there. But here?
  - MrGilbert 2y ago
    I'd argue that people try it every now and then, only to realize that points on HN are worthless. It took me a good amount of years to get some points. I couldn’t care less, because I never saw the benefit. Who knows? Maybe there is a hidden club somewhere where your HN karma will open doors.
- redbell 2y ago
  > I think this is the fourth submission in the past 10 days. I just checked those submissions, and it turned out they were posted in a single day (August 10th) with an eleven-hour time frame! The first submission was at 05:48 AM, the second at 06:37 AM (within less than an hour from the first), and the third at 16:24 PM, which raises one of the weirdest behaviors of the HN system (at least for me): "How or why on earth some submissions got accepted as 'duplicates' where others did not? ". I encounter this a lot when I try to submit a story and it gets rejected because it was already submitted. Sometimes, even if the original story is a month old or more!!
  - latexr 2y ago
    > which raises one of the weirdest behaviors of the HN system (at least for me) I second that. Two months ago I tried to submit what I found to be a quite interesting video from 2018 and it was immediately marked as duplicate: https://news.ycombinator.com/item?id=40798566 https://news.ycombinator.com/item?id=40798566 Checking past submissions, I saw that the last time it had been submitted was a year ago: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&query=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DYThelfB2fvg&sort=byDate&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu... But then, as you can see from that page, someone resubmitted the video a month ago and for some reason that one got through.
- deleted 2y ago
  [deleted]
k_sze 2y ago
Here is an interesting tidbit: the Japanese version of the SNES was called Super Famicom. There was a physical notch that prevented Japanese cartridges from being used in the North American SNES. But for people who knew, it was actually possible to just cut off the notch in the North American SNES, and then you could use Japanese cartridges. My cousin gave me a Japanese Star Fox cartridge back in the days and I could play it on the North American SNES. What I really never understood is how the whole system dealt with the differences between PAL and NTSC. For starters, the Japanese system outputs in PAL, which is 625 horizontal scan lines at ~25 fps. The North American system outputs in NTSC, which is 525 horizontal scan lines at ~29.97 fps. Does anybody understand how that worked?
- siriaan 2y ago
  Japan used NTSC-J, not PAL. Apparently it's close enough to American NTSC that they are basically compatible. https://en.wikipedia.org/wiki/NTSC-J https://en.wikipedia.org/wiki/NTSC-J
- Moru 2y ago
  Europe runs PAL, here it was popular to hunt TV's that could run NTSC because of the higher framerate. This leads to less flicker. All TV's that can run NTSC can also run PAL so you can switch between the 50/60 Hz as you need on computers. Can't remember how it was with consoles, once I got a computer I never really touched a console again :-)
  - singlePostAnon 2y ago
    A lot of TVs sold in European countries since at least the late 1980s / early 1990s could sync to 60Hz just fine, so no need to import TVs or hunt very special ones, just the console hardware if modding it wasn't possible or you didn't want to do it for some reason. Even many of the earlier sets can be made to sync to 60Hz by adjusting vertical hold. Sometimes this control was even available without opening the TV set. Vertical size of the picture may become an issue then, though... (can often be adjusted easily as well but needs opening the set, and then you can't properly watch PAL TV anymore) If using composite video or s-video (Y/C), then NTSC colour encoding could be a problem until some years later, but RGB inputs (via SCART / Péritel) were also very common on European TVs and that bypasses colour encoding / decoding completely (and also gives the best picture quality in general). (well looks like I wasn't going to be a SINGLE post anon after all...)
monero-xmr 2y ago
Nand 2 Tetris (which gets posted on HN a lot, rightly) will give you a fundamental understanding of a lot of these low-level concepts https://www.nand2tetris.org/ https://www.nand2tetris.org/ A good exercise for the junior systems engineer, or someone who wants to fundamentally understand computers better than the REPL, is to build their own emulator. There is likely a wealth of tutorials out there, but if there is not yet a canonical book on how to write an NES, Genesis, SNES, etc. emulator from scratch that can load real ROMs, I think this would really scratch an itch for the aspiring hardcore developer. It is a very illuminating exercise and given the performance of modern computers and the extensive number of graphics libraries for every semi-popular language in existence, I think a universal book could be written that pseudo-codes the concepts of emulation and enables developers of all stripes to build their own emulator.
- j_m_b 2y ago
  I always upvote mentions of Nand2Tetris, this course helped me understand how computers REALLY work. I'm in the middle of writing a Typescript NES emulator. Even with the help of the excellent Mesen emulator, it's a challenging task! It amazes me how people could first write these emulators that worked so well in the 90s with such few resources.
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79 points by grigy 2y ago

skvj 2y ago

excellent SNES PPUs overview, also reading part 2: https://fabiensanglard.net/snes_ppus_why/ https://fabiensanglard.net/snes_ppus_why/

jader201 2y ago

FWIW, this seems to get reposted a lot. I think this is the fourth submission in the past 10 days. Three recent submissions: https://news.ycombinator.com/item?id=41207608 https://news.ycombinator.com/item?id=41207608 (147 points, 8 comments) https://news.ycombinator.com/item?id=41210537 https://news.ycombinator.com/item?id=41210537 (18 points, 2 comments) https://news.ycombinator.com/item?id=41207756 https://news.ycombinator.com/item?id=41207756 (2 points, 0 comments)

pvg 2y ago
You can just flag it as a dupe or email hn@ycombinator.com if you think it's misranked.
deleted 2y ago
[deleted]
0xEF 2y ago
I don't mind reposts now and then, since the odds of two people independently finding the same link interesting over time are pretty good, given the way things tend to circulate on social media and other aggregate platforms. I also worry that HN is slowly turning into a karma farm like Reddit did. The point of reposting on HN just to build Internet Points escapes me,. At least on Reddit there was a market for accounts with high karma, so I guess I could see the motivation there. But here?
- MrGilbert 2y ago
  I'd argue that people try it every now and then, only to realize that points on HN are worthless. It took me a good amount of years to get some points. I couldn’t care less, because I never saw the benefit. Who knows? Maybe there is a hidden club somewhere where your HN karma will open doors.
redbell 2y ago
> I think this is the fourth submission in the past 10 days. I just checked those submissions, and it turned out they were posted in a single day (August 10th) with an eleven-hour time frame! The first submission was at 05:48 AM, the second at 06:37 AM (within less than an hour from the first), and the third at 16:24 PM, which raises one of the weirdest behaviors of the HN system (at least for me): "How or why on earth some submissions got accepted as 'duplicates' where others did not? ". I encounter this a lot when I try to submit a story and it gets rejected because it was already submitted. Sometimes, even if the original story is a month old or more!!
- latexr 2y ago
  > which raises one of the weirdest behaviors of the HN system (at least for me) I second that. Two months ago I tried to submit what I found to be a quite interesting video from 2018 and it was immediately marked as duplicate: https://news.ycombinator.com/item?id=40798566 https://news.ycombinator.com/item?id=40798566 Checking past submissions, I saw that the last time it had been submitted was a year ago: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&query=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DYThelfB2fvg&sort=byDate&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu... But then, as you can see from that page, someone resubmitted the video a month ago and for some reason that one got through.
deleted 2y ago
[deleted]

k_sze 2y ago

Here is an interesting tidbit: the Japanese version of the SNES was called Super Famicom. There was a physical notch that prevented Japanese cartridges from being used in the North American SNES. But for people who knew, it was actually possible to just cut off the notch in the North American SNES, and then you could use Japanese cartridges. My cousin gave me a Japanese Star Fox cartridge back in the days and I could play it on the North American SNES. What I really never understood is how the whole system dealt with the differences between PAL and NTSC. For starters, the Japanese system outputs in PAL, which is 625 horizontal scan lines at ~25 fps. The North American system outputs in NTSC, which is 525 horizontal scan lines at ~29.97 fps. Does anybody understand how that worked?

siriaan 2y ago
Japan used NTSC-J, not PAL. Apparently it's close enough to American NTSC that they are basically compatible. https://en.wikipedia.org/wiki/NTSC-J https://en.wikipedia.org/wiki/NTSC-J
Moru 2y ago
Europe runs PAL, here it was popular to hunt TV's that could run NTSC because of the higher framerate. This leads to less flicker. All TV's that can run NTSC can also run PAL so you can switch between the 50/60 Hz as you need on computers. Can't remember how it was with consoles, once I got a computer I never really touched a console again :-)
- singlePostAnon 2y ago
  A lot of TVs sold in European countries since at least the late 1980s / early 1990s could sync to 60Hz just fine, so no need to import TVs or hunt very special ones, just the console hardware if modding it wasn't possible or you didn't want to do it for some reason. Even many of the earlier sets can be made to sync to 60Hz by adjusting vertical hold. Sometimes this control was even available without opening the TV set. Vertical size of the picture may become an issue then, though... (can often be adjusted easily as well but needs opening the set, and then you can't properly watch PAL TV anymore) If using composite video or s-video (Y/C), then NTSC colour encoding could be a problem until some years later, but RGB inputs (via SCART / Péritel) were also very common on European TVs and that bypasses colour encoding / decoding completely (and also gives the best picture quality in general). (well looks like I wasn't going to be a SINGLE post anon after all...)

monero-xmr 2y ago

Nand 2 Tetris (which gets posted on HN a lot, rightly) will give you a fundamental understanding of a lot of these low-level concepts https://www.nand2tetris.org/ https://www.nand2tetris.org/ A good exercise for the junior systems engineer, or someone who wants to fundamentally understand computers better than the REPL, is to build their own emulator. There is likely a wealth of tutorials out there, but if there is not yet a canonical book on how to write an NES, Genesis, SNES, etc. emulator from scratch that can load real ROMs, I think this would really scratch an itch for the aspiring hardcore developer. It is a very illuminating exercise and given the performance of modern computers and the extensive number of graphics libraries for every semi-popular language in existence, I think a universal book could be written that pseudo-codes the concepts of emulation and enables developers of all stripes to build their own emulator.

j_m_b 2y ago
I always upvote mentions of Nand2Tetris, this course helped me understand how computers REALLY work. I'm in the middle of writing a Typescript NES emulator. Even with the help of the excellent Mesen emulator, it's a challenging task! It amazes me how people could first write these emulators that worked so well in the 90s with such few resources.

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