Windows 2.0 (1987) was a graphical interface developed by Microsoft for personal computers with an MS-DOS operating system. It was introduced in 1987 and was compatible with software developed for Windows 1.0 but provided better management of windows that could now be overlapped. For the first time in a Microsoft system, icons, menus and dialog boxes appear (precisely because of the icons, Apple sued Microsoft for patent infringement but later the judges agreed with Microsoft, rejecting Apple's accusations since this had shared interface rights with Gates' company). DDE (Dynamic Data Exchange) is introduced to facilitate communication between different applications and the SAA (System Application Architecture) standard to make the different applications homogeneous. The performance was improved with a more refined memory management that allowed to exploit part of the extended memory while remaining in real mode, DOS applications could exceed 640 Kilobytes of memory, support was also added to the LIM EMS 4.0 specification (Lotus Intel- Microsoft Expanded Memory Specification). Initially designed for 8086 and 8088 machines, when the 80286 and 80386 processors were introduced, Windows 2.1 (for 80286) and Windows / 386 (for 80386) were released which could also work in 32-bit mode. The combination of Windows 2.0 and these two subsequent extensions was also referred to as Windows 2.x.