CSCI 120 Introduction to Computation Operating System (draft)

So far, we have studied computation from different perspectives, starting from its abstract nature and the design of algorithms all the way to the physical issues involving the electronic representation (bits) and the computer architecture required to carry out the computation. We identified essential components of such an architecture including the CPU, the control unit, the ALU, the registers, the instruction set, main memory, cache memory, the bus, I/O controllers, I/O ports, input and output devices, and mass storage devices. We have also experienced how to write small programs that perform useful operations using the native instruction set, and we have seen some of the programming constructs that a high level programming language would offer to simplify the task of programming, such as functions, loops, conditionals, recursion, etc... Now we ask, what makes everything work together? Who is responsible for coordinating the overall operation of a computer? The answer is the operating system. The operating system is a software program that is loaded into main memory when the computer first starts. This program provides means by which a user can store and retrieve files, provides the interface by which a user can request the execution of other programs, and provides the environment necessary to execute these programs. Examples of operating systems are Windows, MacOS, Unix, and Linux.