Final answer:
UNIX was different from other commercially available software systems due to its open and freely available nature, portability, modular design, and robust networking capabilities.
Step-by-step explanation:
When UNIX was initially developed, it stood out from other commercially available software systems in several ways. Firstly, UNIX was one of the first operating systems to be open and freely available, allowing users to modify and customize it to suit their needs.
This was a significant departure from the tightly controlled, proprietary operating systems offered by other manufacturers.
Secondly, UNIX was highly portable, meaning it could run on different hardware platforms without major modifications. This made it more adaptable and accessible to a wider range of users.
Lastly, UNIX differentiated itself through its modular design and robust networking capabilities. Its modular design allowed for seamless integration of new features and tools, while its networking capabilities enabled easy communication and sharing of resources between different systems.