Yeah, I think the point that @setpatchaddress was trying to make was that the author is confusing the color of the monitor itself with the color prescribed by the software. Thus, take the accuracy of the entire article with a big grain of salt. That's how I understood the comment....
Monochrome monitors were often either green or amber or white. If the monitor used P1 Phosphor, then it was green, P3 Phosphor was amber, and P4 Phosphor was white. So the color of the text on the screen was a reflection of the hardware spec/design, not of the software.
There were also monochrome flat-panel displays, either LCD or plasma. My first¹ computer was a 25Mhz 386 lunchbox luggable with a plasma (amber) display. It was portable-ish and ran on AC power only.
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1. Well really my second. The first was a Spectravideo computer I got for writing demo programs for the midwest distributor when I was in high school. It wasn't very useful though.
Something similar was the first computer I used too. My answer would.be: My dad bought it. This was a common form factor for personal computers back then, and they were sold in stores to to the general public.
At the time I periodically travelled to give LaTeX workshops. I wanted something that I could set up in my hotel room to be able to work on course prep. Laptops were much more expensive and this came out to be competitive, if not cheaper than buying a desktop plus monitor.
Green phosphor coating was cheaper and had a longer "glow" time so it worked better on lower refresh rate equipment. Why they weren't all white later, once that all mattered less, is a good question. I do know that HP charged us more for the white ones...that never changed.
I wonder..."once that all mattered less".... I wonder if, by the time that white CRTs were cheap enough, if color CRTs were also cheap enough (albeit, more expensive than white monochrome), that most consumers just said "f-it, for an extra X, I can have full color instead of _just_ white?"
Blue-green. It was used mostly only in oscilloscopes [1] because the persistence time was really long - good for instruments where the signal might be changing faster than a human can perceive not so much for low latency inputs.
My first response was ¯\_(ツ)_/¯ -- but I dug some more and found out that P2 is a Blue-Green color used in oscilloscopes, but it doesn't look like monochrome computer monitors were ever made for it though [1].
P2 was a long persistence phosphor. It was used in analog oscilloscopes because those couldn't be refreshed -- the waveform was drawn onto the display as it was received, and the phosphor was responsible for making that visible.
You wouldn't want that in a computer monitor. The computer is perfectly capable of refreshing the monitor, and the long duration of the phosphor would make anything rapidly changing (like a scrolling display) impossible to read because all of the previous contents would interfere with the current image.
I was "that guy" during those days and insisted on buying a monochrome CRT (which at that time was just a CRT, since your only choice WAS which "chrome" you chose for your monochrome) whose text was kind of pastel white. It was glorious.
