Operating System Services .Controlled access to files-nature of /O device (disk drive,tape drive)and structure of the data stored in the files in the storage medium.In the case of multiple users accessing the processor concurrently,proper protection mechanisms have to be used. System access-For shared or public systems,the O.S.controls access to the system as a whole and to specific system resources.Access system provides protection of resources,and data from unauthorized users,and resolves resource conflicts Error detection and response-Variety of errors may occur in computer system.Responses may range from program termination,retrial of the same operation,or reporting error to the application. Accounting-collecting usage statistics,CPU usages,monitor performance,etc.Operating System Services • Controlled access to files- nature of I/O device (disk drive, tape drive) and structure of the data stored in the files in the storage medium. In the case of multiple users accessing the processor concurrently, proper protection mechanisms have to be used. • System access- For shared or public systems, the O.S. controls access to the system as a whole and to specific system resources. Access system provides protection of resources, and data from unauthorized users, and resolves resource conflicts • Error detection and response – Variety of errors may occur in computer system. Responses may range from program termination, retrial of the same operation, or reporting error to the application. • Accounting – collecting usage statistics, CPU usages, monitor performance, etc