Operating System Concepts (OS) Notes Free Download
https://mrmwuz.blogspot.com/2015/11/operating-system-concepts-os-notes-free.html
An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. ... The application programs make use of the operating system by making requests for services through a defined application program interface (API).
