Named for one of its designer's daughters, the Lisa was supposed to be the Next Big Thing. It was the first personal computer to use a GUI (Graphical User Interface). Aimed mainly at large businesses, Apple said the Lisa would increase productivity by making computers easier to work with.

The Lisa had a Motorola 68000 Processor running at 5 Mhz, 1 MB of RAM two 5.25" 871k floppy drives, an external 5 MB hard drive, and a built in 12" 720 x 360 monochrome monitor. At $9,995 it was a plunge few businesses were willing to take. When the Macintosh came out in 1984 for significantly less money, it eroded the Lisa's credibility further. Realizing this, Apple released the Lisa 2 at the same time as the Mac. The Lisa 2 cost half as much as the original, replaced the two 5.25" drives with a single 400k 3.5" drive, and offered configurations with up to 2 MB of RAM, and a 10 MB hard drive.

In January 1985, the Lisa 2/10 was renamed the Macintosh XL, and outfitted with MacWorks, an emulator that allowed the Lisa to run the MacOS. The XL was discontinued later that year.

(description pilfered from http://www.apple-history.com/)