Linux kernel an SCM system which satisfied Torvalds' technical requirements. BitKeeper was made available to Linus and several others free of charge but was not free software, which was a source of controversy. The system did provide some interoperability with free SCM systems such as CVS and Subversion. In April 2005, efforts to reverse-engineer the BitKeeper system by Andrew Tridgell led BitMover, the company which maintained BitKeeper, to stop supporting the Linux development community. In response, Torvalds and others wrote a new source code control system for the purpose, called Git. The new system was written within weeks, and in two months
GEOS (8-bit operating system) fully reverse-engineered and rewritten as C for the cc65 compiler suite. The reverse-engineered source code has been made available at Github. Dozens of official and third-party applications and other products were produced for GEOS. Among the most important and popular were the following: GEOS (8-bit operating system) GEOS ("Graphic Environment Operating System") is a discontinued operating system from Berkeley Softworks (later GeoWorks). Originally designed for the Commodore 64 and released in 1986, it provides a graphical user interface for this popular 8-bit computer. GEOS closely resembles early versions of the classic Mac OS and includes a graphical word processor (geoWrite)