Overview : UNIX : Layered Architecture Linux : Monolithic Architecture Windows : Hybrid Architecture (Microkernel + Layered) Mach : Microkernel Architecture. UNIX KERNEL ARCHITECTURE : Unix OS considers files and processes as the most important entities. Unix offers a shell that acts as a command interpreter between the user and the kernel. The relevant […]
Virtualization can be defined as the process of creating multiple copies of an object. A virtual machine is a virtualization of a machine. The software that creates multiple copies of a machine is called a virtual machine monitor (VMM) or a hypervisor. Each virtual machine have its own OS called ‘guest OS’ and the OS […]
There are mainly three types of operating system architecture models : Monolithic OS : Used in older but smaller operating systems. Operating system is divided into procedures. Each procedure have a particular task and all procedures have common data structures and system tables. Each procedure can call other procedures. Resulting in high degree of inter-process […]
There are mainly three types of OS architecture models : Monolithic OS Layered OS Client-server or microkernel OS In every model, there are two modes of processor execution : the user mode and the system mode. Application programs run in the user mode whereas the operating system runs in the system mode. The system mode […]
Before C++ true and false were represented as 1 and 0 respectively. But C++ uses both. Other than 0 all values represent true. Library function exit() : exit(0) : Normal Exit exit(other numerical value) : Error / Abnormal exit. This function is present in ‘process.h’ Library function getche(): This function is present in conio.h No […]
White-space is completely ignored by compiler : Not True. There are few restrictions apply to this rule. e.g. Preprocessor directives must be in same line. ‘cout’ could not be broken. Cout, Cin are objects : These are overloaded. Cout – ‘<<‘ (Put to or insertion operation) and ‘>>’ (extraction or get operator). Directives : Preprocessor […]
The design goals of operating systems are : POSIX Compliance : POSIX (Portable operating system interface bases on Unix) is an IEEE standard 1003.1-1988. This standard helps in bringing comptibility among the various OSes. Extensibility : It is the ability of an OS to grow and change over time, according to the changing requirements of […]
Various types of operating systems are : Single User OS : There is only one user and only his/her programs in the system memory. So there are not security issues too. This type of OS is called a ‘single user mono programming‘. e.g. DOS (Disk operating system) Multi-User OS : System is one but it […]
Every time a computer is turned on a monitor program is loaded from the secondary memory into main memory, which takes control of the computer and provides an interface to interact. Steps involved in booting process of a general OS : Basic Input Output System (BIOS) is stored in ROM, which capable of doing I/O […]
The objectives of an operating system are : Providing the ‘user-friendly’ interface so that the user need not bother about the underlying hard-ware. The commands given by user in an natural language are interpreted by the operating system, which in turn uses the hardware to get the required task done. Creating an environment for other […]