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In a movie that unfortunately I don't remember the name of, a monochrome monitor using red shade was visible. I found that quite fascinating back then !

Beside green, amber and apparently gray, were other colors ever been in use by some obscure hardware ?

Monochrome laptop screens rendering in negative colors are welcome.

Edit

Following participants to this question, some pictures of less conventional than green monitors.

An amber screen in all of its glory (source):

enter image description here

Monochrome plasma of an IBM PS/2 Model P70 (source):

enter image description here

Red color plasma (source):

enter image description here

  • PDP1 used blueish green vector display with long persistance phosphor designed for oscilloscopes. But it was a technical constraint. Green and Amber were chosen, arguably, because they limit eye strain. – TEMLIB Sep 22 '18 at 9:03
  • Monochrome CRT's colors came from the coating. Underneath they were just black and white. – Thorbjørn Ravn Andersen Sep 30 '18 at 11:22
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Non-CRT monochrome screens used various colours related to the underlying technology:

  • monochrome plasma screens were reddish-orange; see for example the PLATO terminals or the Toshiba 4400SX;
  • early LCD screens were bluish, some more than others; I particularly remember early Toshiba laptops being notably blue (see this photo of a T1000), and many “graphical” calculators exhibit this too.

Many monochrome laptops supported “negative” colours, often using a hotkey to flip from “normal” to inverted colours. See Invert LCD screen in DOS 5.0 for an example.

Monochrome CRTs’ colour depended entirely on the phosphor used to coat the display; Wikipedia lists the standard phosphor types, of which there are many. Only a few were used in CRT monitors attached to typical computers, giving the typical green, amber or white displays, but other displays used different colours or phosphors with different decay properties: look for EKG monitors and radar screens in the list.

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    Don't forget early plasma displays that were really red: de.wikipedia.org/wiki/Plasmabildschirm#/media/… – tofro Sep 21 '18 at 9:21
  • @tofro that’s the PLATO terminal, which I linked to — from the photo it doesn’t seem all that red, was it really red or somewhere between red and orange? – Stephen Kitt Sep 21 '18 at 9:32
  • Well I saw pure Orange (not amber) PC CRT monochrome monitors for early PC-AT and late PC-XT out there (not as many as the green ones but still quite a lot) but it vas not VGA I think they where CGA or EGA ... – Spektre Sep 21 '18 at 14:03
  • Yeah, monochrome matrix LCDs progressed from (as I remember it) "blue on (slightly lighter, greenish) blue" to "gray on pale green" to something that you could actually call black and white :) – hobbs Sep 21 '18 at 15:09
  • It's a pity there's so little about that topic on the web :( – Aybe Sep 21 '18 at 17:06
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Beside green, amber and apparently gray, were other colors ever been in use by some obscure hardware ?

Pick any colour you want. The colour is just defined by the emission scheme of the fluorescent material used for the CRT. In fact, doing white is more complex than just doing a single colour. Screens here available with anything from light red to pale blue.

Doing a single colour is much simpler than doing white (or multi colour), as it means only one type of emission coating is needed (like phosphor for green) thus making production less expensive than for white. Also consistent molecule size (as in only one material) enabled a sharper focusing thus a better display.

The spectrum between light (reddish) yellow (often called amber) and green (or more technical 600-500 nm) was a preferred one mainly due the way the human eye works:

The human green sensors a best at 530nm, while the red ones are best at detecting 560nm. Blue lies way of at450nm). In addition to this close and overlapping sensitivity the B&W receptors are fine tuned to 500nm for the highest differentiation.

Also, lower frequency usually means lower energy input, thus the electrons need less acceleration which again results in less X-ray emission. Good for the user being bombarded with.

In addition, using the frequencies the eye is most sensible means the over all brightness (power used) can be turned down, further reducing manufacturing cost (and X-ray emission).

Bottom line, while a monochrome screen is not only the over all lowest cost solution, it also brings several advantages, with yellow/greenish colours being the optimum and a win win situation. That's why other colours haven't been able to gain any hold.

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Xerox Alto workstations and the Xerox D-Machines shipped with monitors that had a long-persistence white phosphor.

  • As did the Wyse WY-700 video card for the IBM PC. – John Dallman Sep 29 '18 at 20:32

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