1. Chapter 4 – Introduction to Operating System Concepts
CMIT100
Chapter 4 – Introduction to Operating System Concepts

2. Learning Objectives Describe the roles of the operating system.
Compare the graphical user interface and the command line interface.
Describe virtual memory.
Describe the boot process and system initialization.

3. Operating Systems The OS is Software Two general types:
Software that allows the user to interface with the hardware
Two general types:
CLI, command line interface
Control of the OS is done only by commands typed in at a command line
GUI, graphical user interface
Control of the OS is done primarily by using a mouse, or a touchscreen, to execute commands by clicking on images

4. Operating Systems
CLI
Why even talk about this, all OS’s are now GUI based
Not… there is a CLI only version of Windows Server called the Core version
It is also possible to create a basic Windows PE boot device that is CLI only… part of CMIT 215, and learning the Windows CLI
Not having a GUI in a Windows Server means that it is:
“Lighter weight” requires less resources in computing power
Relatively more secure as it is not running various services
Think… you can never check your or surf the web on a core version
There are also some versions of Linux that can be installed to run only a CLI

5. Operating Systems What does the CLI look like? The mac OS CLI
Accessed by executing a “terminal” window

6. Operating Systems What does the CLI look like? The Linux CLI
Again, accessed via a terminal or console session from a Linux desktop GUI

7. Operating Systems What does the CLI look like? The Windows CLI
Accessed… easiest way… Win Key + R, CMD, Enter

8. Operating Systems GUI The most commonly used type of OS Includes:
Windows
mac OS on a Macintosh platform
Formerly known as OS X
Based on Unix
iOS on an Apple iPhone or iPad
Another Unix variant
Linux, many different versions
Often called distributions (flavors)
Android on a smahtphone or tablet
Based on Linux
Chrome OS on a Chromebook

9. Basic Terminology Hardware
The physical components of the computer system:
Internal components are primarily situated (integrated or connected to) the motherboard or mainboard
Motherboard = the largest circuit board in any type of system
Motherboards, as we saw in a previous chapter have:
Sockets, where a CPU is mounted
Slots, where RAM modules are inserted
Expansion slots, where additional add-on expansion cards are inserted
Mainly in desktops for advanced video cards, etc.

10. Basic Terminology Software The programs that the system runs
OS = system software, programs that the computer runs to maintain its environment
Application software = software that performs some type of task
Software exists only as electrical current flowing through the computer (or as magnetic charges stored on some type of permanent or temporary storage device)

11. Functions of an OS The OS consists of: Kernel Device drivers Shell
Utility programs
Tasks
Process management
Scheduling
Memory management
Resource management
File system management
Protection and security

12. Functions of an OS The Kernel
The core of the OS; we differentiate this portion from other parts that are added on by users: shells, device drivers, utilities.
The kernel includes the programs that perform the primary OS tasks: process management, resource management, memory management, file management, protection, and security.

13. Functions of an OS The kernel
When we think kernel, we most often think of the version of the OS
Windows 10 has a newer kernel than does Windows 8
Windows Server 2012 has an older kernel than does Windows Server 2012 R2
Ubuntu Linux has a different kernel than Red Hat Linux
Etc

14. Functions of an OS The kernel
Linux is an “open source” operating system
Which means that anyone can modify the kernel of the OS
This is what results in the hundreds of versions (distributions) of Linux
Windows, considered a closed sourced operating system (like mac OS) can not be legally modified
Why would you want to modify the kernel of an OS???

15. Functions of an OS Device drivers
Software that is specific to your OS version, and a hardware device in your system unit.
A device driver is required for each hardware device.
Microsoft bundles many different device drivers in each version of their OS.
OEM systems are setup in the factory with all specific device drivers.
Even though Windows may install a device driver for a device when you are performing a clean install (bare metal install), you will often want to install a device driver that came with the device, or was downloaded, to take advantage of advanced features of the device.
Some device drivers must be installed manually as the device was not recognized by Windows.

16. Functions of an OS Shell
Term for the type of interface you are utilizing as a user.
Simply:
GUI
CLI
Windows and mac OS come with one GUI shell
Linux distributions use many different versions of GUI shell

17. Functions of an OS Utility programs
Software that helps manage and fine-tune the hardware, OS, and applications software.
File management utilities
Windows File Explorer
mac OS Finder
Windows disk management console
AntiMalware utilities
Etc.

18. Functions of an OS Process management
The main task of any computer is to run programs.
A program being executed by the computer is called a process.
The difference between a program and process is that a program is a static entity, whereas a process is an active entity.
Processes have a state:
A status might be
“running” (process is currently being executed by the CPU)
“waiting” (process is waiting for input or output, or waiting to be loaded into memory),
“ready” (process is loaded into memory but not currently being executed by the CPU).

19. Functions of an OS Scheduling
Provides the ability of the OS to keep open and running more than one program at a time.
Multitasking is not processing instructions for more than one program at a time.
Scheduling sends program processes to the CPU on a shared scheduled basis

20. Functions of an OS Memory management
Because main memory (RAM) is smaller in size than the size of the software we typically want to run, the OS is in charge of moving chunks of programs and data into and out of memory as needed.
As users are often running more programs (multitasking) than will fit in RAM, all current OSs create swapfiles
Swapfile = a file on a HDD that contains data for running programs that there is no space for in RAM
What is written to the swapfile is based on the priority of the running program
In Windows is called PAGEFILE.SYS, usually located in the root of the %systemdrive%

21. Functions of an OS Resource management
Aside from memory and the CPU, there are many other resources available including the file system, access to the network, and other devices.
The OS maintains a table of all active processes and the resources that each process is currently using or wants to use.
Most resources can only be accessed in a mutually exclusive way. That is, once a process starts using a resource, no other process can use the resource until the first process frees it up.
Once freed, the OS can decide which process next gets to access the resource.
Example: A web browser needs to access the NIC at the same time you are printing to a network printer.

22. File system management
Functions of an OS
File system management
The primary task of early OSs was to offer users the ability to access and manipulate the file system (the name MS-DOS stands for Microsoft Disk Operating System, and the commands almost entirely dealt with the disk file system).
Typical commands in file management are to open a file, move a file, rename a file, delete a file, print a file, and create, move, rename, and delete directories (folders).
Today, these capabilities are found in file manager programs such as Windows Explorer.
Although these commands can be performed through dragging, clicking, etc., they are also available from the command line.

23. Protection and security
Functions of an OS
Protection and security
Most computers these days are a part of a larger network of computers where there may be shared files, shared printers, or other shared resources.
Additionally, multiple users may share the same computer.
The files stored both locally and over the network must be protected so that a user does not accidentally (or maliciously) overwrite, alter, or inappropriately use another user’s files.

24. Protection and security (cont.)
Functions of an OS
Protection and security (cont.)
Protection ensures that a user is not abusing the system—not using someone else’s files, not misusing system resources, etc.
Security extends protection across a network.
Security in this aspect is any given user’s permission to access files on a local machine or over the network.

25. Functions of an OS
Windows has two levels of permissions that can be assigned to a file or folder:
Security permissions (AKA NTFS permissions)
Apply to a locally logged on user
Exist by default
Share permissions
Apply to a user accessing the shared resource over the network
Do not exist by default

26. Booting and System Initialization
Steps:
Turn the system on
The BIOS (basic input output system) performs the POST (power on self test) where it checks the availability and integrity of the devices contained within the system unit, including:
RAM
Permanent storage devices, HDD, DVD, and any connected UFDs for UHDs
Video output devices
NICs
Input devices (mouse, keyboard)
Clock
Even such things as CPU temperature and CPU fan speed

27. Booting and System Initialization
POST (cont.):
As the BIOS checks for all of the devices it loads very basic device drivers to allow a user to interface with the hardware in order to install an OS if none exists.
Obviously an OS is required to load device drivers.
The OS is firmware… a basic user interface written to the BIOS chip.
The BIOS checks for an installed OS signature on the available permanent storage devices
If the BIOS finds the installed OS, it starts the OS boot process
Control of the hardware now moves to the OS