The Lisa was a personal computer designed by Apple Computer, Inc. during the early 1980s.
It was the first personal computer to offer a graphical user interface in an inexpensive machine aimed at individual business users. Development of the Lisa began in 1978.
In 1982, after Steve Jobs was forced out of the Lisa project, he joined the Macintosh project. The Macintosh is not a direct descendant of Lisa, although there are obvious similarities between the systems. The final revision, the Lisa 2/10, was modified and sold as the Macintosh XL.
The Lisa was a more advanced system than the Macintosh of that 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. The Macintosh featured a faster 68000 processor (7.89 MHz) and sound. The complexity of the Lisa operating system and its programs taxed the 5 MHz Motorola 68000 microprocessor so that consumers said it felt sluggish, particularly when scrolling in documents.