Unix vs Linux vs Windows vs Osx

UNIX/Linux vs Mac vs Windows

By

Jesse Cunningham, Ernest Ramos, Derick Fisher, Jonathan Coyle, Gary Geihsler

POS/355

October 15, 2012

Hasan Abu-Zaina

The UNIX Operating System

UNIX is a multitasking, multi-user computer operating system (OS) developed in 1969 at Bell Labs by a group of AT&T employees. The original OS used an assembly language that was almost entirely recoded in C by 1973. This change helped facilitate it for future development and the porting of new and different hardware. Presently, the Unix systems has been split into multiple branches with continuous development by AT&T and various commercial vendors and like other major operating systems, Unix allows use of all its physical memory in a system and areas on the disk (swap space) designated for kernel use, in case there is a lack of physical memory for a task. The total physical memory and sum of swap space gives virtual memory. The kernel creates manageable memory blocks called pages. These pages are applied to virtual and physical memory.

Swapping and demand paging is how space is allocated in memory for different processes that user(s) requests. Sleeping processes switch to a swap device whenever RAM is insufficient. Any Ready to Run processes switches back into RAM. Transferring between swap device and RAM is basically the process of things; however, there are some disadvantages, such as limited processes at once and those processes greater than RAM never executes. When a disk page copies into physical memory of the system, this is called demand paging (an application of the virtual memory). For an example, when a page fault occurs it is controlled by the kernel (the master control program). Only a few pages loads into the RAM and once the CPU finishes loading, it asks for the next page requested.

UNIX data organizes into files, which places into the directories. The directories use a tree type architecture that is also the file system. A great deal of time...