Complex sentence: 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, called Lisa Workshop, was required.
Split into simpler sentences: 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, called Lisa Workshop, was required.