I wanted to start this thread to talk about specific stuff at the moment, but there's still quite a bit I'd like to discuss relative to all things NTSC - as well.
First off is the issue of Japanese game consoles on US NTSC sets. Japanese systems uses the full voltage range from blanking (0v) to max. While US TV sets start black at IRE 7.5. Showing a Japanese console on a US TV basically crushes very dark colors. But what about full white? I keep getting conflicting results.
Some sites list 100 IRE as max white (which is 0.714v from what I've gathered). Other sites give the Luma range in 8bit quantized steps.. 16 to 235. To me, this suggests two things if you map that range into logic of IRE levels; A) 235 doesn't represent IRE 100 or B) it does represent IRE 100 but there's whiter than white allowed (Luma voltage above 0.714v). There's conflicting information about this EVERYWHERE.
Secondly, if NTSC-J starts 'black' as blanking or IRE 0, then what's the cap at? Higher than NTSC-U of 0.714v? The reason I ask, is that looking at my Japanese SGX on the scope - Luma isn't 0 to 0.714 (ignoring sync level). It's 0 to 0.84v. Well, at least that's what the game system is outputting for max white: 0.84v. I has a rom board for my PCE/SGX, but unfortunately not for my SNES and Genesis. And.. both of those are US systems - not Japanese. So I can't run comparative Luma range tests on them.
Any ideas? There are a number of reason I want to know this, but one of them is to make a circuit to scale and offset the composite output into the correct range. I don't want to scale the top level incorrectly if 0.714 != 0.84 in equiv range for JP and US standards. I mean, I want to keep the 'whiter than white' if that is the case for NTSC-J standard too, when transforming this to NTSC-U.
Edit:
Secondly, NEC didn't bother fixing the NTSC-J issue for the US Duo models. Black is IRE 0. Max white was 1v (!), but I think my amping circuit in my Duo is on the fritz (I've been cutting traces and jumping them ,etc). I'm curious about the NES and SNES. Were these corrected or left as is like the Duo (don't know about the TG16 because I don't have one on hand to test).
First off is the issue of Japanese game consoles on US NTSC sets. Japanese systems uses the full voltage range from blanking (0v) to max. While US TV sets start black at IRE 7.5. Showing a Japanese console on a US TV basically crushes very dark colors. But what about full white? I keep getting conflicting results.
Some sites list 100 IRE as max white (which is 0.714v from what I've gathered). Other sites give the Luma range in 8bit quantized steps.. 16 to 235. To me, this suggests two things if you map that range into logic of IRE levels; A) 235 doesn't represent IRE 100 or B) it does represent IRE 100 but there's whiter than white allowed (Luma voltage above 0.714v). There's conflicting information about this EVERYWHERE.
Secondly, if NTSC-J starts 'black' as blanking or IRE 0, then what's the cap at? Higher than NTSC-U of 0.714v? The reason I ask, is that looking at my Japanese SGX on the scope - Luma isn't 0 to 0.714 (ignoring sync level). It's 0 to 0.84v. Well, at least that's what the game system is outputting for max white: 0.84v. I has a rom board for my PCE/SGX, but unfortunately not for my SNES and Genesis. And.. both of those are US systems - not Japanese. So I can't run comparative Luma range tests on them.
Any ideas? There are a number of reason I want to know this, but one of them is to make a circuit to scale and offset the composite output into the correct range. I don't want to scale the top level incorrectly if 0.714 != 0.84 in equiv range for JP and US standards. I mean, I want to keep the 'whiter than white' if that is the case for NTSC-J standard too, when transforming this to NTSC-U.
Edit:
Secondly, NEC didn't bother fixing the NTSC-J issue for the US Duo models. Black is IRE 0. Max white was 1v (!), but I think my amping circuit in my Duo is on the fritz (I've been cutting traces and jumping them ,etc). I'm curious about the NES and SNES. Were these corrected or left as is like the Duo (don't know about the TG16 because I don't have one on hand to test).