Apple Lisa(1983)
Apple invents the personal computer. Again.
Background
The Lisa was the first personal computer to offer a graphical user interface in an inexpensive machine aimed at individual business users. The Lisa was a more advanced system than the Macintosh of this time in many respects, such as its inclusion of protected memory, preemptive multitasking, a generally more sophisticated hard disk based operating system, a built-in screensaver, an advanced calculator with a paper tape and RPN, support for up to 2 megabytes (MB) of RAM, expansion slots, a numeric keypad, data corruption protection schemes such as block sparing, non-physical file names (with the ability to have multiple documents with the same name), and a larger higher-resolution display. It would be many years before many of those features were implemented on the Macintosh platform. Protected memory, for instance, didn't reappear until the Mac OS X operating system was released in 2001.