Jobs came up with the idea of Lisa OS after looking at the mouse-supported interface image when visiting Xerox PARC. From what he saw, he created his own version - Lisa operating system with GUI, mouse support and file system. Although Lisa's computer was not as popular as Jobs expected, it marked an important milestone for many of today's OSs.
The emulator tools to run Lisa OS have been around for a while, but those who want to discover the source code of this OS will have to wait a while longer. Kossow also said that the only thing not released is the American Heritage Dictionary for spell checking on LisaWrite. Anyway, it's free to get the source code of such a historic OS, no spell checker is too important.
See more: