Rollback. Hardware support improvements such as FireWire 800, and improvements to multi-monitor support under the name "DualView". Fast user switching. The ClearType font rendering mechanism, which is designed to improve text readability on liquid-crystal display (LCD) and similar monitors, especially laptops. Side-by-side assemblies and registration-free COM. General improvements to international support such as more locales, languages and scripts, MUI support in Terminal Services, improved Input Method Editors, and National Language Support. Removed features Some of the programs and features that were part of the previous versions of Windows did not make it to Windows XP. Various MS-DOS commands available in its Windows 9x predecessor were removed, as were the POSIX and OS/2 subsystems. In networking, NetBEUI, NWLink and NetDDE were deprecated and not installed by default. Plug-and-play–incompatible communication devices (like modems and network interface cards) were no longer supported. Service Pack 2 and Service Pack 3 also removed features from Windows XP, including support for TCP half-open connections and the address bar on the taskbar. Editions Windows XP was released in two major editions on launch: Home Edition and Professional Edition. Both editions were made available at retail as pre-loaded software on new computers and as boxed copies. Boxed copies were sold as "Upgrade" or "Full" licenses; the "Upgrade" versions were slightly cheaper, but require an existing version of Windows to install. The "Full" version can be installed on systems without an operating system or existing version of Windows. The two editions of XP were aimed at different markets: Home Edition is explicitly intended for consumer use and disables or removes certain advanced and enterprise-oriented features present on Professional, such as the ability to join a Windows domain, Internet Information Services, and Multilingual User Interface. Windows 98 or Me can be upgraded to either edition, but Windows NT 4.0 and Windows 2000 can only be upgraded to Professional. Windows' software license agreement for pre-loaded licenses allows the software to be "returned" to the OEM for a refund if the user does not wish to use it. Despite the refusal of some manufacturers to honor the entitlement, it has been enforced by courts in some countries. Two specialized variants of XP were introduced in 2002 for certain types of hardware, exclusively through OEM channels as pre-loaded software. Windows XP Media Center Edition was initially designed for high-end home theater PCs with TV tuners (marketed under the term "Media Center PC"), offering