PROCESS manager: Handles the creation of and operations upon processes. A process is a unit of resource management, including an address space and one or more THREADS.

Thread manager: Thread creation, synchronization and scheduling. Threads are scheduled activities attached to processes.

Communication manager: Communication between threads attached to different processes on the same computer. Some kernels also support communication between threads in remote processes. Other kernels have no notion of other computers built into them, and an ADDITIONAL service is required for external communication. 

Memory manager: Management of physical and virtual memory.

Supervisor: Dispatching of interrupted, system call traps and other exceptions: control of memory management unit and hardware caches; processor and floating point unit REGISTER manipulations. This is known as the Hardware Abstraction LAYER in Windows NT.

Process manager: Handles the creation of and operations upon processes. A process is a unit of resource management, including an address space and one or more threads.

Thread manager: Thread creation, synchronization and scheduling. Threads are scheduled activities attached to processes.

Communication manager: Communication between threads attached to different processes on the same computer. Some kernels also support communication between threads in remote processes. Other kernels have no notion of other computers built into them, and an additional service is required for external communication. 

Memory manager: Management of physical and virtual memory.

Supervisor: Dispatching of interrupted, system call traps and other exceptions: control of memory management unit and hardware caches; processor and floating point unit register manipulations. This is known as the Hardware Abstraction Layer in Windows NT.