Operating System StructuresTypes

1. Simple Structure

Such structure doesn’t have well-defined structure. Systems that uses such structure are simple and for limited systems. An example for this structure is MS-DOS. You can see figure of MS-DOS structure below:

Hardware also affects such structures. Traditional UNIX also used simple structure because had limited hardware. You can see figure of such structure below:

2. Layered Approach

With proper hardware support, operating system can be broken in pieces that are smaller and more appropriate and can maintenance better. You can see the figure of layered structure below:

A typical operating system layer— for example, layer M— consists of data structures and a set of routines that can be invoked by higher-level layers.

3. Microkernel

When the UNIX became larger, the kernel of the UNIX also became larger and was hard to manage. In the mid-1980s, researcher at Carnegie Mellon University developed an operating system called Mach. Mach that modularized the kernel using the microkernel approach. In this approach, all nonessential component removed from kernel and implemented as system or user-level program. You can see figure of approach below:

4. Modules

Perhaps the best approach for design of the current operating system is loadable kernel modules. Here, the kernel has a set of components and links in additional services via modules, either at boot time or during run time. You can see structure of Solaris loadable modules as below:

5. Hybrid Systems

In most operating systems, they combine different structures, resulting in hybrid systems that have performance, security, and usability issues. Examples of such structures:

MAC OS X

iOS

Android

VxWorks

- Structure:

- System Call:

- TCB

a thread of execution; that is, the task's program counterthe CPU registers and (optionally) floating-point registersa stack for dynamic variables and function callsI/O assignments for standard input, output, and errora delay timera time-slice timerkernel control structuressignal handlersdebugging and performance monitoring values

- End of Task

taskDelete() API

References

[1] A. Silberschatz, Operating System Concepts, 2012.

[2] "vxworks_kernel_programmers_guide_6.2," [Online]. Available: https://www.uio.no/studier/emner/matnat/fys/FYS4220/h11/undervisningsmateriale/laboppgaver-rt/vxworks_kernel_programmers_guide_6.2.pdf.

[3] "TCB in VxWorks," [Online]. Available: http://comp.os.vxworks.narkive.com/0awyxysO/tcb-in-vxworks.