Third-party Software
A significant impediment to third-party software on the Lisa was the fact that, when first launched, the Lisa Office System could not be used to write programs for itself: a separate development OS was required called Lisa Workshop. During this development process, an engineer ran the two OSes in a dual-boot config, writing and compiling code on one machine and testing it on the other. Later, the same Lisa Workshop was used to develop software for the Macintosh. After a few years, a Macintosh-native development system was developed. For most of its lifetime, the Lisa never went beyond the original seven applications that Apple had deemed enough to "do everything."
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