<Table> Unix <Tr> <Td_colspan="2"> Evolution of Unix and Unix - like systems </Td> </Tr> <Tr> <Th> Developer </Th> <Td> Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna at Bell Labs </Td> </Tr> <Tr> <Th> Written in </Th> <Td> C and assembly language </Td> </Tr> <Tr> <Th> OS family </Th> <Td> Unix </Td> </Tr> <Tr> <Th> Working state </Th> <Td> Current </Td> </Tr> <Tr> <Th> Source model </Th> <Td> Historically closed - source, while some Unix projects (including BSD family and illumos) are open - source </Td> </Tr> <Tr> <Th> Initial release </Th> <Td> Development started in 1969; 49 years ago (1969) First manual published internally in November 1971 (1971 - 11) Announced outside Bell Labs in October 1973 (1973 - 10) </Td> </Tr> <Tr> <Th> Available in </Th> <Td> English </Td> </Tr> <Tr> <Th> Kernel type </Th> <Td> Varies; monolithic, microkernel, hybrid </Td> </Tr> <Tr> <Th> Default user interface </Th> <Td> Command - line interface and Graphical (X Window System) </Td> </Tr> <Tr> <Th> License </Th> <Td> Varies; some versions are proprietary, others are free / open - source software </Td> </Tr> <Tr> <Th> Official website </Th> <Td> opengroup.org/unix </Td> </Tr> </Table> <Tr> <Td_colspan="2"> Evolution of Unix and Unix - like systems </Td> </Tr>

Who are primarily credited with the development of the unix operating system