I just wanted to ask what is bioskey() , what does it do, and how to use it?

>what is bioskey()
An obsolete function that some old compilers support.

>what does it do
It sends the 16h interrupt so that you can get direct keyboard access without using inline assembly.

>and how to use it?
Don't. It probably won't work anymore and there are better ways to get similar effects using system APIs.