On the history of screens and light versus dark... [The TL;DR answer is "technological limitations of the era."]
Way back, in the days when Smalltalk was but a gleam in its fathers' eyes, we had CRT technology. You know, magnetic coils sweeping a beam of electrons across a phosphor coated glass surface to make the phosphor glow and present images to people on the other side of the glass. There were two common forms of this device: computer terminals and televisions. There wasn't a lot of difference between the two. Back in those days, the electron beam hitting the phosphor typically caused a lot of "blooming" in terms of how much illumination occurred. In other words, when writing green text on black, the pixels of phosphor glowed brighter and spread out a bit into the surrounding black. Inverse video text, on the other hand, showed a green or white background with black text (the absence of electrons hitting the phosphor). The bloom from the background squeezed in to the letter space and made letters much harder to read. Back in the 60s and 70s, computer screens tended to support 80x24 (or 25) lines of text. 80 because that was the width of a Hollerith punched card, of course. Graphics? Almost unheard of. There were efforts like Sketchpad [Sutherland, and probably et al.]. Graphics didn't make much of an appearance until the mid-70s with the early personal computers, most notably the Apple II. The earlier Radio Shack TRS-80 was purely character oriented, and the Exidy Sorcerer was character oriented but allowed one to programmatically define the glyphs used for the character set (which allowed a limited form of graphics). Those early PCs utilized existing screen technology for their displays. By "existing", I mean televisions. The RF (radio frequency) conversion and the sloppy/low resolution of TVs at that time still left one with a greatly limited display capability. The first IBM PCs came with a CGA resolution video adapter. You can look up the details. It was limited, to say the least. About this time, the market for specialized monitors took off and the use of TVs as monitors started to dwindle. Coincident with this, the computer graphics market took off and the specialized monitors / resolution race began. With higher and higher resolution and better electronics, the phosphor bloom effect was correspondingly reduced. And of course, with solid state displays, the bloom effect disappeared entirely. (It's hard to have that bloom when there is no phosphor and no electron beam sweeping over it.) Coincident with the introduction of bitmapped graphics (the Smalltalk machines, things like the envisioned Dynabook, and so on) created the opportunity to have displays that mimicked the way we worked outside the computer world. i.e. dark text on white paper. -- View this message in context: http://forum.world.st/Dark-Mode-tp4964409p4965170.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
