Services provided by an operating system to the Program

• Context Switching & Scheduling, which allocate a process CPU, time to execute its instructions.
• Memory Management, which deals with allocating memory to processes.
• Interprocess Communication, which deals with facilities to allow concurrently running processes to communicate with each other.
• File Systems, which provide higher level files out of low level unstructured data on a disk.
• High level I/O facilities, which free a process from the low-level details of interrupt handling.

Services provided by an operating system to the User

1. Program execution:
The operating system loads the contents (or sections) of a file into memory and begins its execution.
2.  I/O operations:
 Disks, tapes, serial lines, and other devices must be communicated with at a very
Low level. The user need only specify the device and the operation to perform on it, while the system converts that request into device or controller specific commands.

3.  File-system manipulation:
 Programs need to read and write files. Programs also need to create and delete files by name.
4. Communications:
Communications may be implemented via shared memory, or by message passing, in which packets of information are moved between processes by the operating system.

5. Error detection:
 Error detection occurs at both the hardware and software levels. The operating
System should take the appropriate action to ensure correct and consistent computing.