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 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 Mac OS. The XL was discontinued later that year.

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