heh and I found linux's EDID database, and a quick grep later wouldn't you know it, monitors are all over the place in what signal levels they report.

12895 report IBM VGA 0.7V p-p.

10566 report PAL 1V p-p, -0.3V to 0.7V.

62 report NTSC 1V p-p, -0.286 to 0.714V

Not much of a pattern in the non-0.7Vp-p ones so far. Samsung and Dell account for a large number of them, but they account for a large number of monitors of that era generally. Maybe manufacturing date?...

Not really! There are EDIDs from monitors manufactured in 2022 that request 1V p-p output! What the hell?

One awk script later, date seems irrelevant: from 1995 through 2022 manufacturing dates, 0.7Vp-p and 1Vp-p monitors are represented in approximately equal amounts in the EDID database. Certainly same order of magnitude. Which I find completely bemusing for several reasons, one being: wait people are still _making_ new analog monitors??

more scripts later, no obvious pattern other than the monitors advertising 1Vp-p seem cheaper and nastier, which makes me wonder if there's some popular legacy VGA decoder chip that they all slap on the board to get an extra port to sell and that chip just doesn't give a fuck?

Hahaha wait no, I have a better, much worse theory.

They're all reporting the 1Vp-p variant that ranges -0.300V to 0.700V. Which is the bit value `000` in EDID.

My new theory is those monitors just didn't bother setting a value in that field, because the monitor worked fine with the default so who cares.

Which, yeah, it does, because they also all specify "blank level equals black level", meaning the pixel data swings 0V through 0.7V, with -0.3V being used only for sync pulses.

... But modern graphics cards don't send composite sync pulses on the pixel lines, they all use separate TTL wires for those. So, the -0.3 to 0.7 and 0 to 0.7 EDID values are functionally identical in practice, as long as your EDID also tells the sender that "Separate" sync signals are supported. Which these EDIDs all do.

Some of the monitors advertise that they will understand sync pulses sent on separate wires, or in the NTSC-style composite form, or in the "Sync on Green" form where the green analog line behaves differently to red and green.

But most say they only understand separate sync signals. Making the advertisement of supporting full 1Vp-p swings irrelevant, because they then immediately say "oh but I don't understand the thing you'd do with 0.3V of that range, so, uh, I guess 0.7Vp-p really"

And kinda regardless of what sync modes the monitor offers, who the hell in this day and age is making a VGA output driver and isn't going to use the 5-wire form that is utterly universal and doesn't require extra conditionals to maybe decide to gratuitously scream NTSC every now and again. If the drivers even look for any of this any more, I wager they ignore the advertised signal level entirely and just panic is black-is-blank and separate-sync aren't set in EDID.