1. The document discusses the major components of operating system structures including process management, main memory management, file management, I/O system management, secondary storage management, networking, protection systems, and command interpreter systems. 2. It also describes operating system services such as program execution, I/O operations, file system manipulation, communications, error detection, and resource allocation. 3. The types of system calls are outlined related to process control, file manipulation, device manipulation, information maintenance, and communication.