What is an OS?
it is a software that controls a computer.
It manages hardware, controls applications, provides an interface for users, and stores, retrieves, and manipulate files.
DOS was the first OS among IBM computers
DOS can b used to boot and troubleshoot a computer.
Windows XP/2000 offers a recovery console and a command prompt window where you use DOS like commands.
Windows 9x/Me = backward compatibility with older software and hardware while still taking advantage of newer technology.
The only time u would install a cop of windows 9x/Me is in a situation of corrupted installation or replacing a hard drive.
Windows NT became in 2 versions
Windows NT Workstation and Windows NT Server
Windows 2000 is considered a dying OS
Windows XP has the ability for two users to log on simultaneously
Windows Vista coded name Longhorn
Linux was created by Linus Trovalds
Distributions by redhat; SUSE.
Linux is very reliable and does not require a lot of computing power, sometimes used as desktop OS
MAC OS has it roots in the Unix OS
First introduced in 1984
Provides excellent support for graphics and multimedia apps
The newer version provides better support for multitasking and thus less likely to freeze when several apps r running.
Four main functions for OS
- Providing User Interface;
- Managing Files;
- Managing Apps;
- Managing Hardware.
Every OS has two main internal components
Shell(relates to user and apps) and Kernel (interacts w/hardware).
Windows uses a database called registry
Windows keeps some data in txt files called initialization files
GUI (graphical user interface)
OS is responsible for storing files and folders on a secondary storage device, using an organizational method called file system.
For hard drives windows uses either FAT (file allocation table)or NTFS(New tech file system) file system.
FAT: Tracks how space on a disk is used to store files.
NTFS: designed to provide greater security and to support more storage capacity.
A hard drive or floppy is composed of tracks, divided on sectors. Each sector holds 521 bytes.
A Cluster, the smallest unit of space on a disk for storing a file , is made of one or more sectors.
A File System tracks how these clusters are used for each file stored on a disk.
Every OS manages a hard drive by using directories, subdirectories and files.
Directory table is a list of subdirectories and files.
Logical drives are called volumes.
When each logical drive is formatted, a single directory table is placed on the drive called the root directory.
Drive and directories are called path to the file.
A hard drive is organized in one or more partitions. It can b primary or extended partition. A primary partition can have only one logical drive and the extended can have one or more.
File systems for Windows and DOS system
FAT 16; FAT 32; NTFS
An OS installs and runs all the other software on a PC. Software designed to perform a task for the user is called an app.
OS is responsible for installing the software using the installation prgrm provided by the app.
before an app can b use, it must b started up, which is caled running, loading, lauching or executing the app.
Four ways to run a software on Windows 2000/XP
- Use a shortcut icon;
- Use the start menu;
- Use the run cmmnd
- Use Windows explorer or my computer
CPUs operates in three modes
- 16 bit (Real) - early comp. (an app had complete access to all hardware resources) - Windows 3x (not supported by ME)
- 32 bit (protect) - Windows NT/2000/XP (allows one on more pgm to run)
- 64 bit (Long) - Windows XP Professional
- Windows 95 was the first version to provide preemptive multitasking.
- Windows NT was the first windows OS to support multiprocessor.
Three high end processors that operate in 64 bit
Itanium, AMD Opteron and AMD Athlon
Most software falls into three categories
- Device drivers or the BIOS
- App software,
Device drivers re small programs stored on the hard drive that tell the comp how to communicate with a specific hardware device such as a printer, network card, or modem.
System BIOS (basic input/output system) on the motherboard is hard-coded or permanently coded into a comp chip called firmware or ROM Bios Chip. Can b used to access the hard drive.
The OS is responsible for moving data and instructions in and out of memory and for keeping up with what is stored where.
If the OS is low in RAM, it can store some data on the hard drive. This is called virtual memory. it is store on a swap file or page file.
The Windows Desktop is the primary tool provided by the Windows Shell.
Apps at the top of the Start Menu are said to be called Pinned
A Taskbar is located at the bottom of the windows desktop. displaying info about open prgms.
System tray is usually on the right side of the task bar and display open services.
Service is a pgm that runs in the background to support or serve windows or an app. (volume control and networking activity).
Two most useful tools to explore files and folders on ur computer are My Computer and Windows Explorer.
The easiest way to manage drives, disk, folders is thru shortcut menus.
Emptying the recycle bin will free up ur disk space.
Using Explorer or My comp, u can view and change the properties assigned to a file. These properties are called file attributes.
There is one attribute of a file called the system attribute, that says a file belongs to the OS.
Windows id the files by their extensions.
Remote tab, manage how outside users can control ur computer
Device manager is ur primary windows tool when solving problems w hardware. u can mk changes and update drivers, unistalled device drivers.
Use the WIndows System Info utility to examine ur system.