Editing Genera (operating system) (section)

== Genera operating system ==
[[Symbolics]] developed new [[Lisp machine]]s and published the operating system under the name ''Genera''. The latest version is 8.5. Symbolics Genera was developed in the early 1980s and early 1990s. In the final years, development entailed mostly patches, with very little new function.

Symbolics developed Genera based on this foundation of the MIT Lisp machine operating system. It sells the operating system and ''layered software''. Some of the layered software has been integrated into Genera in later releases. Symbolics improved the operating system software from the original MIT Lisp machine and expanded it. The Genera operating system was only available for Symbolics Lisp machines and the Open Genera [[virtual machine]].

Symbolics Genera has many features and supports all the versions of various hardware that Symbolics built over its life. Its source code is more than a million lines; the number depends on the release and what amount of software is installed. Symbolics Genera was published on [[magnetic-tape data storage|magnetic tape]] and [[CD-ROM]]. The release of the operating system also provided most of the source code of the operating system and its applications. The user has free access to all parts of the running operating system and can write changes and extensions. The source code of the operating system is divided into ''systems''. These systems bundle sources, binaries and other files. The ''system construction toolkit'' (SCT) maintains the dependencies, the components and the versions of all the systems. A system has two numbers: a major and a minor version number. The major version number counts the number of full constructions of a system. The minor version counts the number of patches to that system. A ''patch'' is a file that can be loaded to fix problems or provide extensions to a particular version of a system.

Symbolics developed a version named ''Open Genera'', that included a virtual machine that enabled executing Genera on DEC Alpha based workstations, plus several Genera extensions and applications that were sold separately (like the Symbolics ''S-Graphics'' suite). Also, they made a new operating system named ''Minima'' for embedded uses, in [[Common Lisp]]. The latest version is ''Portable Genera'', which has the virtual machine ported to [[x86-64]], [[Arm64]] and [[Apple M1]] processors - additionally to the [[DEC Alpha]] processor. The virtual machine then runs under the [[Linux]] and [[macOS]], additionally to [[Tru64 UNIX]].

The original Lisp machine operating system was developed in [[Lisp Machine Lisp]], using the ''Flavors'' object-oriented extension to that Lisp. Symbolics provided a successor to Flavors named ''New Flavors''. Later Symbolics also supported [[Common Lisp]] and the [[Common Lisp Object System]] (CLOS). Then Symbolics Common Lisp became the default Lisp dialect for writing software with Genera. The software of the operating system was written mostly in Lisp Machine Lisp (named [[ZetaLisp]]) and Symbolics Common Lisp. These Lisp dialects are both provided by Genera. Also parts of the software was using either Flavors, New Flavors, and Common Lisp Object System. Some of the older parts of the Genera operating system have been rewritten in Symbolics Common Lisp and the Common Lisp Object system. Many parts of the operating systems remained written in ZetaLisp and Flavors (or New Flavors).