Very true - the X-windows graphical interface was not available in Unix systems for a long time after Unix was available.

Very true - the X-windows graphical interface was not available in Unix systems for a long time after Unix was available.

It would take a very long time to learn all of the Unix commands, and frankly, that isn't necessary. Most Unix users have a subset of commands they use all the time, and that is how they learn them.

Some versions of Unix are oriented towards real time applications, and processes in Unix can be "promoted" to real time status if desired. Other than that, you would have to define more precisely what you mean by real time for an operating system.

Unix was first developed in assembly language in 1973. Academic circles studied Unix around this time and even into the early 1980's. It was first licensed in 1974.