1. Overview of Operating Systems
Introduction
Software that runs computer
General Purpose (PC to Mainframe)
Mission Specific (robot, real-time computer)

2. Overview of Operating Systems
Purpose of an operating system?
To facilitate easy, efficient, fair, orderly, and secure use of computer resources
Software: spreadsheets, word processors, Web browsers, , games, graphing tools, etc.
Hardware: RAM, CPU, keyboard, mouse, disks, modem, printer, screen, video card, etc.

4. Figure 1.1 A layered view of a contemporary computer system2

5. Overview of Operating Systems
Resource Manager/ Virtual Machine
e.g. allocates/manages on RAM, CPU, disks, printer queues, etc.
e.g. isolates you from the complications of hardware resources. (mouse, disk, DVD, etc.)
Unix/Linux command example:
cp memo memo_backup

6. Overview of Operating Systems
Operating System Services
execution of a program
input & output operations performed by program
communication between processes
error detection & reporting
manipulation of all types of files

7. Overview of Operating Systems
Character Versus Graphical User Interface
Character User Interface (CUI)
(command-line user interface)
Graphical User Interface (GUI)
(point-and-click device)
Linux has both.
GNOME (GNU Network Object Model Environment)
KDE (K Desktop Environment)

8. Overview of Operating Systems
Type of Operating Systems
Single-user, single-process
DOS, MacOS, Window 3.1
Single-user, multiprocess
OS/2, Window NT Workstation
Multiuser, multiprocess
LINUX, UNIX, Window NT Server

9. Overview of Operating Systems
Multiuser, multiprocess systems are used to increase resource utilization.
To increase throughput (# of precesses finished in unit time)

10. Overview of Operating Systems
multiprogram : The mechanism of assigning the CPU to another process when the current process is performing I/O.
interactive OS, batch OS
Interactive: LINUX, UNIX, DOS, Windows, VMS
Batch: payroll
LINUX/UNIX has both.
time-sharing systems
CPU is switched from one process to another in quick succession to allow all process in the system to make progress, giving each user the impression of sole use of the system.

11. UNIX / LINUX History UNIX:
Conceived & implemented in 1969 at AT&T’s Bell Laboratories by Ken Thompson, Denis Ritchie, Douglas McIlroy, and Joe Ossanna.
Released in 1971, written entirely in assembly language
Rewritten in 1973 in C , with exceptions to the kernel and I/O, by Dennis Ritchie

12. UNIX / LINUX History UNIX:
The availability of an operating system written in a high-level language allowed easier portability to different computer platforms. With a legal glitch forcing AT&T to license the operating system's source code, Unix quickly grew and became widely adopted by academic institutions and businesses.

13. UNIX / LINUX History GNU Project: Started in 1983 by Richard Stallman
had the goal of creating a "complete Unix-compatible software system" composed entirely of free software

14. UNIX / LINUX History GNU GPL:
Free Software Foundation was created in 1985 by Richard Stallman
GNU General Public License (GNU GPL) written in 1989
By the early 1990s, many of the programs required in an operating system (such as libraries, compilers, text editors a Unix shell, and a windowing system) were completed, although low-level elements such as device drivers, daemons, and the kenels were stalled and incomplete.

15. UNIX / LINUX History GNU Project:
Linus Torvalds has said that if the GNU kernel had been available at the time (1991), he would not have decided to write his own.

16. UNIX / LINUX History
Richard Stallman, left, founder of the GNU Project, and Linus Torvalds, right, principal author of the Linux kernel

17. UNIX / LINUX History MINIX
Andrew S. Tanenbaum, author of the MINIX operating system

18. UNIX / LINUX History MINIX:
MINIX was an inexpensive minimal Unix-like operating system, designed for education in computer science

19. UNIX / LINUX History LINUX:
In 1991 while attending the University of Helsinki, Torvalds, curious about the operating systems and frustrated by the licensing of MINIX limiting it to educational use only (which prevented any commercial use) began to work on his own operating system which eventually became Linux.

20. UNIX / LINUX History LINUX:
GNU GPL applications & codes replaced all MINIX ones
In order to make the Linux available for commercial use, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL.

21. Advantages & Disadvantages of Running UNIX/LINUX
Advantage #1 – Stability
If an application crashes in Linux, it will usually not harm the kernel or other processes.
Advantage #2 – Free Software
Most software can be obtained without cost for Linux. e.g. Open Office. (Conversion isn’t 100% perfect)

22. Advantages & Disadvantages of Running UNIX/LINUX
Advantage #3 – Runs on old hardware
Runs on old 386 or 486 with 1GB disk and 16MB memory. With a large disk and using Samba to make your machine share the disk as a Windows share.
Advantage #4 – Security (a double-edged sword)
The code being in the public domain

23. Advantages & Disadvantages of Running UNIX/LINUX
Disadvantage #1 – Learning Curve
NO instant gratification. Takes time to learn.
Don't expect to be an expert after reading something like “Linux for Dummies”. Budget some money for training and learning time.
Disadvantage #2 – Equivalent Programs
There are still applications that do not exist in Linux. . It may not make sense for you to switch if you are going to spend tons of time converting databases and application data.

24. Advantages & Disadvantages of Running UNIX/LINUX
Disadvantage #3 – More Technical Ability Needed
Make sure that you train someone in Linux really well. A good Linux administrator needs to be on hand as you start to migrate your systems over. This is a disadvantage financially, at least in the beginning.
Disadvantage #4 – Not All Hardware Compatible
the latest and greatest hardware that is being produced is not compatible with Linux. Ask if the hardware vendor has support for Linux. Some manufacturers do write their own Linux drivers and distribute them with your purchase. Rely on third-party drivers and other means to make hardware like a new Ethernet card work, sometimes.

25. LINUX Installation Options
Dual boot or Virtual Linux
Download & Install VirtualBox. (SUN->ORACLE)
Then, Install Linux On The VirtualBox
Download & Install Linux/Debian Latest Stable Release.
After Successful Linux/Debian Installation:
apt-get upgrade
apt-get update

26. Debian: Directory Structure
/ - Root directory.
/bin- Essential command binaries.
/boot- Static files of the boot loader.
/dev- Device files.
/etc- Host-specific system configuration.
/home- User home directories.
/lib- Essential shared libraries and kernel modules.
/mnt- Mount point for mounting a filesystem temporarily.
/opt - Add-on application software packages.
/proc – System configuration parameters.
/root - Home directory for the root user.
/sbin - Essential system binaries.
/sys - Virtual file systems which stores and allows modification of devices connected to the system. Symbolic links to the kernel source tree.
/tmp - Temporary files.
/usr - Secondary hierarchy.
/var - Variable data.