In the following years more and more modifications were developed, including ones that focus on other aspects, like finance. For example, Microsoft acquired a Unix V7 license in 1979 to develop ports for Intel and Motorola processors, among other things. In the following year, they released Xenix, which was originally planned as a standard operating system for PCs but ended up placing hardware demands that were too high. Microsoft finally placed further developments in the hands of the software manufacturer SCO (Santa Cruz Operation) to concentrate on OS/2 and further development of MS-DOS.
Bill Joy also jumped on the bandwagon in 1982 with his newly founded company Sun Microsystems, using the proprietary BSD-based system SunOS (predecessor of Solaris), which was specifically designed to use on servers and workstations.
However, the real battle for Unix fans was fought between AT&T, which by now had received commercial distribution permission, and Berkeley University, which was able to highlight valuable innovations, thanks to their large number of supporting programmers. AT&T first tried to conquer the market with System III (1981) and with the new optimized version of System V (1983), both of which were based on Unix V7. The University of Berkeley then simultaneously released 4.3BSD, for which 1,000 licenses were issued within 18 months. This made it much more popular than the paid System V, which lacked the file fast system (FFS) and the network capability (thanks to integrated TCP/IP) of Berkeley’s variant.
With System V’s fourth release (1988), AT&T implemented these two and many other BSD features, as well as for Xenix and SunOF, which led to many users switching to the commercial option.