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I'd like to make my text editors display like the old skool white-on-green VDUs of yore that I can just about remember from my childhood. I have this idea they might be easier on my old eyes.

I was wondering if there was standard dark green used on these and, if so, what the RGB or Hex values for it might be?

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DaveBoltman's answer is very remarkable and useful. However, the phosphors' wavelengths in Wikipedia are not exact. There are other references and Google books giving slightly different values. For instance, P1 w/l is 525, not 528 nm: http://www.labguysworld.com/crt_phosphor_research.pdf

Anyway, I remember what colors those phosphors displayed (including the amber phosphors), so I am nearly sure of these RGB and Hex values:

enter image description here

I suppose that Apple //c and Apple /// monitors used the P24 GE phosphor, because they had its hue. And the background of the old monochrome CRTs usually was lighter than pure black, see this photo:

https://upload.wikimedia.org/wikipedia/commons/6/69/IBM_PC_5150.jpg

For better eye comfort, I suggest that the OP use any of those greens with that background. In the dark, the old-fashioned green on dark gray looks better than the present black on white.

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    It's funny after all this time, eyes feel better with basic combination of ambar or green on black. Just created iTerm2 profile based on your answer. Good stuff, thank you
    – mau
    Sep 16, 2019 at 23:52
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    I'm unclear what you mean by hex color #XXXXXX = YYY nm, as that certainly doesn't make sense as an equation. The real-life color produced by some RGB color will depend highly on the display. Which was the original and how did you derive the other from it?
    – Apollys supports Monica
    Dec 2, 2019 at 22:26
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    incidentally, for historical reasons or not, amber and green on "black" are used in most modern arliner cockpit instruments and displays. They are mostly bright text on dark background. And you can imagine the variance of ambient light conditions in an aircraft cockpit, and the split-timing decisions that need to be made after noticing a certain light signal
    – Ate Somebits
    Feb 18, 2021 at 12:53
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Inspired by the below (incomplete) answers:

  1. Almost all the "'old fashioned' green screen computer displays/VDUs" used the P1 phosphor (see wikipedia reference)

  2. The P1 phosphor produces a peak wavelength (a.k.a. colour in human terms) of 528 nm (reference)

  3. Converting colour from a wavelength to RGB values (in the commonly used byte format of 0 to 255) using formulae here, gives: Red=65 Green=255 Blue=0, or #41FF00 in hexadecimal. (see this convertor).

  4. This does not take brightness into account. (to adjust the brightness the RBG value would need to be converted to HSV, have the V component adjusted up or down, then converted back to RGB to satisfy the OP).

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  • There wasn't a standard color.
  • Brightness is part of color and was usually changeable by turning a knob.
  • Colors change as the phosphor ages.
  • You could order VDUs with amber and other color phosphors.
  • Some makers claimed amber was better for eyes.
  • The ones I used were mostly green on black (not white on green)
  • RGB values probably depend on calibration of your display.
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    "Some makers claimed amber was better for eyes." - Medically-prescribed 'VDU' glasses were/are amber-tinted (a relative worked in a medical eye centre)
    – Linker3000
    Nov 25, 2011 at 12:52
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    in short. do what a lot of nostalgic geeks do, and adjust it till it looks right
    – Journeyman Geek ♦
    Nov 25, 2011 at 13:22
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    Unfortunately I don't really remember what it looked like. I was <10yrs old at the time :-|
    – immutabl
    Dec 3, 2011 at 23:43
  • I've tried both amber and green. In hindsight I liked the amber best.
    – Thorbjørn Ravn Andersen
    Nov 26, 2019 at 6:23
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From Wikipedia you can find a wavelength of this phosphor and RGB conversion formulas can be found easily from internet.

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    Wow! Now that's what I call a geeky answer. Many, many thanks for this amazing idea!
    – immutabl
    Nov 25, 2011 at 19:30
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Try RGB color code:

R:36
G:204
B:68

For a result like this:

enter image description here

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    Why do you think this is the right color? Other answers provide some insight and reasoning. How can we tell it's not just your opinion or a wild guess?
    – Kamil Maciorowski
    Feb 20, 2018 at 21:31

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