The Lisa was first introduced on January 19, 1983. It is one of the first personal computer systems with a graphical user interface (GUI) to be sold commercially. It uses a Motorola 68000 CPU clocked at 5 MHz and has 1 MB of RAM. It can be upgraded to 2 MB and later shipped with as little as 512 kilobytes. The CPU speed and model was not changed from the release of the Lisa 1 to the repackaging of the hardware as Macintosh XL.