UNIX Operating Systems and Kernels Presented By: Walter Haynes April 26, 2007

Abstract This presentation relates to the UNIX operating system and its kernels. It shows the design and productivity of the four major kernels that are used today and gives a comparative analysis of them. It also talks about the conflict between the monolithic and micro kernels as it relates to the Tanenbaum – Torualds Debate who are the creators of the MINIX and Linux versions of UNIX.

Introduction In the UNIX Operating System the kernel is the master control program of the computer. It manages the computer’s resources and handles the switching necessary to provide multitasking. Today there’s many different types of kernels based on the way the version was written. Today there’s four major kernels being used the micro, monolithic, hybrid, and exokernels.

UNIX And Its Beginning UNIX is one of the oldest operating systems made. It consist of: Kernel – Master control program File System – Organizes data into files and directories Shell – Interrupts user commands for the kernel Utilities – Useful Software tools

BSD (Berkeley Software Distribution)‏ One of the Several Branches of the UNIX Operating System. Created in the 1970s by students at University of California at Berkeley.

BSD PDP-11 The first UNIX system at Berkeley was a PDP-11(Programmed Data Processor) installed in The PDP-11 was a series of 16-bit microcomputers, sold by the Digital Equipment Corp.

BSD VAX-11 The PDP-11 was later replace with the VAX- 11 (Virtual Address Extension)‏ This processor was an 32-bit extension that support an Orthogonal instruction set which allows it to use data of any type via any addressing mode

1BSD In 1977, Bill Joy released First Berkeley Software Distribution (1BSD). This Version was an add on to the 6 th Edition of UNIX Today, he is the Co- founder of Sun Microcomputers

MINIX Created by Andrew S. Tanenbaum at Vrije Universiteit in Amsterdam. Wrote 12,000 lines of code mainly in C, source code of the kernel, memory manager, and file system of MINIX 1.0 Tanenbaum’s design principle influenced the design of Linus Torualds creation of the Linux Kernel

What is a Kernel? Every operating system has a kernel. The task of an operating system’s kernel is to take care of the most basic of tasks a computer operating system must perform: assign hardware resources to software applications in order for them to complete the tasks the users want them to do. For instance, when you browse through the world wide web, your browser needs processor time to properly display the web pages, while also needing space on your hard drive to store commonly accessed information, such as login credentials or downloaded files. While it is the task of the operating system to properly spread the computer’s resources across running applications, it is the kernel that performs the actual act of assigning.

Monolithic Kernel Kernel Space User Space System Call Interface Kernel Contains: Memory Management, Processor Scheduler, Interprocess Communication, File System, I/O Manager, and Net Manager Software Kernel

Microkernel Kernel ServersSoftware IPC User Space Kernel Space

Tanenbaum – Torualds Debate The Difference in the Kernels MINIX’s Microkernel Vs. Linux’s Monolithic Kernel This Difference started this debate stating that Linux’s monolithic kernel was obsolete Kernel Design

Hybrid Kernel User Space Kernel Space Server Kernel Software

Exokernel Library Software Kernel User Space Kernel Space

Resources Andersen, Paul K.(2003) Just Enough UNIX, 4 th Ed. New York, NY. McGraw Hill Deitel, Deitel, and Choffnes. (2004) Operating Systems 3 rd Ed. Upper Saddle River, NJ. Pearson-Prentice Hall Englander, Irv. (2003) The Architecture Computer Hardware and System Software: An Information Technology Approach 3 rd Ed. John Wiley& Son Inc. Null, Linda and Julia Lobur. (2006) The Essentials of Computer Organization and Architecture 2 nd Ed. Sudbury, MA Jones and Barrlett Tanenbaum, Andrew. (2001) Modern Operating System. 2 nd Ed. Upper Saddle River, NJ. Prentice Hall