has many features not found in previous versions of Windows.
Improved device support
Windows XP provides new and/or improved drivers and user interfaces for devices compared to Windows Me and 98.
Windows Image Acquisition (WIA), originally introduced in Windows Me, replaced the traditional TWAIN support for scanners and digital cameras. As TWAIN does not separate the user interface from the driver of a device, it is difficult to provide transparent network access; whenever an application loads a TWAIN driver, it is completely undetachable from the supplied manufacturer's GUI.
Still Image (STI) support is provided as a compatibility layer within the WIA subsystem.
On old versions of Windows, when users upgrade a device driver, there is a chance the new driver is less efficient or functional than the original. Reinstalling the old driver can be a major hassle and to avoid this quandary, Windows XP keeps a copy of an old driver when a new version is installed. If the new driver has problems, the user can return to the previous version. This feature does not work with printer drivers.
Windows XP includes a new set of visual themes, known by its codename, Luna. Available in three schemes, the interface is more task-based than the basic one included since Windows 95, with options available in Explorer windows to interact with each file. It also includes other modifications, such as grouping of related programs, hiding of taskbar icons, and many other elements.
Fast User Switching
Fast User Switching allows another user to log in and use the system without having to log out the previous user and quit his or her applications. Previously (on both Windows Me and Windows 2000) only one user at a time could be logged in (except through Terminal Services
), which was a serious drawback to multi-user activity. Fast User Switching, like Terminal Services, requires more system resources than having only a single user logged in at a time and although more than one user can be logged in, only one user can be actively using their account at a time. This feature is not available when the Welcome Screen is turned off, such as when joined to a Windows Server Domain
or with Novell Client installed.
Remote Assistance allows a Windows XP user to temporarily take over a remote Windows XP computer over a network or the internet to resolve issues. As it can be a hassle for system administrators
to personally visit the affected computer, Remote Assistance allows them to diagnose and possibly even repair problems with a computer without ever personally visiting it.
Windows XP includes technology from Roxio
which allows users to directly burn files to a compact disc through Windows Explorer. Previously, end users had to install CD burning software, such as Nero Burning ROM
. Now, CD and DVD-RAM
burning has been directly integrated into the Windows interface; users burn files to a CD in the same way they write files to a floppy disk or to the hard drive. The burning functionality is also exposed as an API called the Image Mastering API
. Windows XP's CD burning support does not do disk to disk copying or disk images
although the API can be used programmatically to do these tasks. Creation of audio CDs is integrated into Windows Media Player
Windows XP includes ClearType sub-pixel font anti-aliasing
, which makes onscreen fonts smoother and more readable on liquid crystal display
(LCD) screens, although this causes a minor performance hit. Although ClearType has an effect on cathode ray tube
(CRT) monitors, its primary use is for LCD/TFT-based (laptop, notebook and modern 'flatscreen') displays.
Users can log into Windows XP Professional remotely through the Remote Desktop service. It is built on Terminal Services technology (RDP
), and is similar to Remote Assistance
, but allows remote users to access local resources such as printers. . Any Terminal Services client, a special "Remote Desktop Connection" client, or a web-based client using an ActiveX
control may be used to connect to the Remote Desktop. (Remote Desktop clients for earlier versions of Windows, Windows 95, Windows 98 and 98 Second Edition, Windows Me, Windows NT 4.0, or Windows 2000, have been made available by Microsoft .
This permits earlier versions of Windows to connect to a Windows XP system running Remote Desktop, but not vice-versa.)
There are several resources that users can redirect from the remote server machine to the local client, depending upon the capabilities of the client software used. For instance, File System Redirection allows users to use their local files on a remote desktop within the terminal session, while Printer Redirection allows users to use their local printer within the terminal session as they would with a locally or network shared printer. Port Redirection allows applications running within the terminal session to access local serial and parallel ports directly, and Audio allows users to run an audio program on the remote desktop and have the sound redirected to their local computer. The clipboard can also be shared between the remote computer and the local computer.
Before Windows 98, power management was based on the Advanced Power Management
architecture. It was of limited use to most users and the feature was easily broken by the addition of hardware devices or software. Windows XP's power management architecture is based on the ACPI
standard and still supports APM. (In Windows 98 ACPI was supported but disabled by default. Windows Me enabled ACPI by default.) It supports multiple levels of sleep states, including critical sleep states when a mobile (or UPS
connected) computer is running out of battery power, processor power control (the ability to adjust the speed of the computer's processor on-the-fly to save energy), selective suspend of externally attached (such as USB) devices, and turning off the power to the screen of a laptop when the lid is closed. In addition, it also dims the screen when the laptop has low battery power.
When Windows XP hibernates
it dumps the entire contents of the RAM
to disk and powers down the entire machine. On startup it quickly reloads the data back to RAM. This allows the system to be completely powered off while in hibernate mode. This requires a file the size of the installed RAM to be placed in the system's root directory, using up space even when not in hibernation. Hibernation is enabled by default and can be disabled in order to recover disk space.
The Windows hibernation feature conforms to the S4 Sleep State in the ACPI standard.
Standby (Sleep) mode
When Windows enters standby mode, it turns off all nonessential hardware, including the monitor, hard drives, and removable drives. This means that the system reactivates itself very quickly when "woken up". This does not power down the system. In order to save power without user intervention, a system can be configured to go to standby when idle and then hibernate if not re-activated.
The Windows Standby feature conforms to the S1 and S3 Sleep States in the ACPI standards.
The Windows XP kernel
is completely different from the kernel of the Windows 9x/Me line of operating systems. As an upgrade of the Windows 2000 kernel, the improvements are major, albeit transparent to the end user. They include some enhancements to the scalability and performance of the system.
Windows XP includes Simultaneous Multithreading Support, or the ability to utilize the Hyper-Threading feature of newer Intel Pentium 4 processors. Simultaneous Multithreading is a processor's ability to process more than one data thread at a time. Intel has described the effect as being more or less 70% that of having the processing power of two processors.
The ability to boot in 30 seconds was a design goal for Windows XP, and Microsoft's developers made efforts to streamline the system as much as possible; many people have found that without extra services Windows XP can boot from the PC's power on self-test (POST) to the Windows GUI in about 30 seconds. The Prefetcher is a significant part of this; it monitors what files are loaded during boot, and optimizes the locations of these files on disk so that less time is spent waiting for the hard drive's heads to move.
As Windows XP merged the consumer and enterprise versions of Windows into one, it folded the user-friendly interface of Windows Me onto the kernel of Windows 2000. A drawback of this is that older software designed for previous versions of Windows may not function. Microsoft addressed this by going to great lengths to improve compatibility with application specific tweaks and shims and providing tools to allow users to try these tweaks and shims on their own applications.
Application isolation & side-by-side assemblies
A common issue in previous versions of Windows was that users frequently suffered from DLL hell
, where more than one version of the same Dynamically Linked Library
(DLL) was installed on the computer. As software relies on DLLs, using the wrong version could result in non-functional applications, or worse. Windows XP solved this problem by introducing side-by-side assemblies
. The technology keeps multiple versions of a DLL in the WinSxS
folder and runs them on demand to the appropriate application keeping applications isolated from each other and not using common dependencies.
Windows XP also introduced a new mode of COM object registration called Registration-free COM. This makes it possible for applications that need to install COM objects to store all the required COM registry information in the application's directory, instead of in the global registry, where, strictly speaking, only a single application will ever use it. DLL hell can be substantially avoided using Registration-free COM, the only limitation being it requires at least Windows XP or later Windows versions and that it must not be used for EXE COM servers or system-wide components such as MDAC, MSXML, DirectX or Internet Explorer.