Virtualization of OS

What is Virtualization?

Virtualization allows multiple operating system instances to run concurrently on a single computer;
it is a means of separating hardware from a single operating system. Each “guest” OS is managed by a Virtual Machine Monitor (VMM), also known as a hypervisor. Because the virtualization system sits between the guest and the hardware, it can control the guests’ use of CPU, memory, and storage, even allowing a guest OS to migrate from one machine to another.

DOS Operation

Before knowing the operations of DOS, we must know what DOS is. DOS stands for disk operating system. The term DOS can refer to any operating system, but it is most often used as a shorthand for MS-DOS (Microsoft disk operating system). Originally developed by Microsoft for IBM, MS-DOS was the standard operating system for IBM-compatible personal computers.

DOS uses a command line, or text-based interface, that allows the user to type commands. By typing simple instructions such as pwd (print working directory) and cd (change directory), the user can browse the files on the hard drive, open files, and run programs.

Ms-Dos Interface

Compiler, Interpreter, Linker and Loader

Regardless of what language you use, you eventually need to convert your program into a language that the computer can understand
Two ways for doing that: compile the program or interpret the program

Compiler 

A compiler is a computer program that translates a program in a source language into an equivalent program in a target language. 

OR

A program that translate a source (human-writable) program to an executable (machine-readable) program.

OS, Types of OS, Functions of OS and Utility Software

Operating System Concept

What is an operating system?
A number of definitions of operating system abound. A basic definition could be that it’s a program that lets you run other programs.The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command line or a graphical user interface (GUI).
An operating system is basically a intermediary agent between the user and the computer’s resources (CPU (process scheduling), memory (memory management), display, keyboard, mouse (device drivers), persistent storage (file systems), and the network).