Windows Mobile 6.5
The first Windows Mobile 6.5 devices was first shown on September 2009. While not officially available to the public as of July 2009, leaked ROMs have surfaced for specific devices. The generic ROM images for Windows Mobile 6.5 are also available as part of the officially distributed and freely downloadable development kit.
Windows Mobile 6.1
Microsoft’s current Windows Mobile release is Windows Mobile 6.1, and one of the major changes from WM6 is the introduction of instant messaging-like texting. Windows Mobile 6.1 was built upon Windows CE 5.
Windows Mobile 6
Microsoft’s Windows Mobile 6, internally code-named ‘Crossbow’, was officially released by Microsoft on February 12, 2007. Windows Mobile 6 was still based on Windows CE 5 and was effectively just a face lift of Windows Mobile 5. With Windows Mobile 6 also came Microsoft’s new naming conventions and devices were no longer called Pocket PCs. Windows Mobile Classic would become the name for Pocket PC type devices without phone capabilities and Windows Mobile Professional would be used for devices with phone capabilities.
Windows Mobile 5
Windows Mobile 5 for Pocket PC was based on Windows CE 5 and contained numerous fixes and improvements over Pocket PC 2003 SE.
Pocket PCs running previous versions of the operating system generally stored user-installed applications and data in RAM, which meant that if the battery was depleted the device would lose all of its data. Windows Mobile 5.0 solved this problem by storing all user data in persistent (flash) memory, leaving the RAM to be used only for running applications, as it would be on a desktop computer. As a result, Windows Mobile 5.0 Pocket PCs generally had a greater amount of flash memory, and a smaller amount of RAM, compared to earlier devices
Windows Mobile 2003
Windows Mobile 2003 consisted of the Windows CE.NET 4.2 operating system bundled with scaled-down versions of many popular desktop applications, including Microsoft Outlook, Internet Explorer, Word, Excel, Windows Media Player, and others.
Windows Mobile 2003 Second Edition added native landscape, square screen and VGA support as well as other fixes and changes to those features already present in the original release of Windows Mobile 2003.
Pocket PC 2000 and 2002
Pocket PC 2002 (launched October 2001) and Pocket PC 2000 (launched April 2000) both ran Windows CE 3.0 underneath. Some Pocket PC 2002 devices were also sold as “Phone Editions” which included cell phone functionality in addition to the PDA capabilities.