== History ==
Already in the 80's, only few years after the release of the [[Commodore C6464]], the legendary [http://en.wikipedia.org/wiki/GEOS_%288-bit_operating_system%29 GEOS] by Berkeley Softworks appeared and set the standard for a windows-based operating system on c64. It was a graphical user-interface (GUI) which was similar to the old desktop of the Apple Macintosh. Powerfull applications were made available for GEOS like GeoWrite (similar to MS-Word) or GeoCalc (similar to MS-Excel). It was incredible, that an 8bit-machine with only 64K was able to realize such an operating system.
On the Amstrad CPC many efforts to build a decent GUI were made as well. In most cases they were just extensions to realize a WIMP (Windows, Icons, Menus and Pointers) environment but weren't true operating systems with their own kernel, memory-management and so on. The [[CEUS Desktop 2.0|CEUS Desktop 2.0 (1990)]] by Prodatron was just such an extension-system.