1981 - Xerox Star
1984 - Mac - System OS 1.0
1985 - Atari - TOS 1.0
1985 - Amiga - Workbench 1.0
Xerox invented it and I am a big :amiga: Amiga fan here (had one) but let’s admit in terms of icons, fonts, proportions, spacing or generally speaking taste the original Apple design is still brilliant.
@santiago there was also the GEM OS. But I have to say that using the Xerox one (I knew it as Documenter) was amazing. In particular if networked: you could just drag a document and drop it in a printer that could even be in another country. And the use of properties (the keyboard had a Props key): you could select a letter or a paragraph, for instance, hit Props and change the font, size, alignment, whatever made sense as a property in that context. And the mouse it used was optical!
@santiago I was starting my "working life" and indeed, I felt lucky to use, and in some cases maintain, some of those systems that were not common at all. All in all, it has been interesting, from seeing Dad with a sliding rule to this day's where I am communicating to someone somewhere in the world using a tiny gadget I am holding in my hand.
