Right yes ok so you’re talking about the dithering in the original artwork that gets ‘noised’ during transmission to the CRT which is what my first thoughts were when you mentioned dithering.
Essentially this should happen when using ntsc-adaptive.slangp no? I haven’t tested the megadrive again yet. I’ll give it a spin!
Sorry, I can’t comment on the actual capabilities of NTSC-adaptive, it’s obviously more flexible than those old 256px NTSC etc. shaders that were there first (great). My personal project in the near future is trying to explore the capabilities of MAME-HLSL a bit for the purpose of colour artifacting (=turn something monochrome into colour on a specific platform).
I will however leave another link, concerning dithering, this is a video that explains Playstation dithering in detail, mentioning for example how it’s an actual hardware feature:
N64 did hardware level blending. At least I think it was hardware.
At 8:40 there’s also talk about the N64, there’s actually quite an amount of different examples shown, it’s great. (I’m not associated with the channel in any way 
)
N64 and PS1 both have hardware-level dithering, though PS1’s is just a basic pattern overlay.
Re: NTSC simulation in general, you can isolate the NTSC passes from MAME-HLSL and, while I don’t think they generally look as good as ntsc-adaptive (which is just the ntsc-256/320-px shaders mooshed together with some logic to choose which one to use), they do expose a lot more signal values for tweaking. See: dannyld’s mega drive rainbow thread for more details.
I like the idea of different modules for different systems. The TurboGrafx 16 for example was known for having a very clean composite output, while the Genesis was terrible.
To do this we would need to get all the systems to one person so they can be connected to the same display, in order to eliminate the display as a variable. Or just get the raw captures from different people, but that seems harder?
So most of the above stuff as far as I can tell is stuff that should be emulated by whatever core we’re using at the time as in it falls outside the domain of a CRT shader. Certainly PS1 and N64 dithering falls into that camp. What we’re really interested in are the black boxes that is the output circuitry. I’m not terribly certain a whole lot of progress has been made in this area of emulation - there was a video on the SNES circuitry I watched a couple of years back that talked about it. I’ll try and find it.
It was actually an article I was remembering and it sounds like they actually did emulate the things I was talking about
NTSC aka Never The Same Color 
It’d be really great if we knew what the PPUs were doing. Is there a big difference in gamma between SNES and NES? There are no settings that look right for both systems. Seems like a 0.20 - 0.30 difference in output gamma is required. I think I recall reading somewhere that the SNES had a very saturated output, so it kinda makes sense that a higher output gamma would be needed, if true.
FYI one of the NES presets uses 1.80 gamma. I wonder if, other than using a power-pc Macintosh, there is any reason for this 
\presets\nes-color-decoder+colorimetry+pixellate
I feel like we haven’t paid enough attention to NES color palettes on this forum. Then again it is a can of worms!
Is this PAL or NTSC?
This is from a PAL Wii. Note though that I didn’t turn the sharpness control all the way down for these photos, that would make a difference for composite, though not the extent it would suddenly mimic Genesis/Megadrive output.
Wasn’t aware of this until I stumbled over it recently. At least some Sony WEGAs have adjustment settings for their comb and notch filters in service mode.
I also read that on some sets you can even disable interlacing, though probably not on the WEGAs.This brings back memories of me stumbling my way through the service menu 
It’s the AEG CTX 480 preset on my shader (Sony Megatron) underneath the shaders/HDR folder. Simply get the latest version of RetroArch and then go to online update and update slang shaders (I think you need to use D3D11, d3d12 or vulkan). The shader does require a very bright screen - normally HDR capable but supports bright SDR only displays like laptops.
@MajorPainTheCactus Oh sure, I’m familiar with your shader. But I was talking about what settings you’re using to achieve that NTSC look that’s a bit sharper than the NTSC-Adpative.
So I decided to attempt to go down the rabbit hole of trying to replicate the NES composite output. Unfortunately I no longer have access to real hardware, but when I last did, it was a front loader NTSC NES hooked up to a Sony 27FS100. I recall despite it having access to a 3D comb filter IIRC, the grunginess of the composite output shone through regardless, and it is this I am now trying to achieve.
I found a pretty good close-up picture that I think encapsulates rather well how I remember the NES looking:
I got pretty close using CRT-Guest-Advanced-NTSC, but I’m still playing with it. For sure it requires a decent bit of fringing with no field merging, as I definitely recall the image being flickery, but without much artifacting. I’m torn on the blend mode, though. It almost looks correct with it on, but then things like the brown of the bricks bleeding into the black gap between the bricks, whereas they appear almost wholly black in the picture. I’ll have to mess with it some.
Did you achieve that with any kind of sharpening? Where is the fringing coming from?