Editing Tierra (computer simulation) (section)

{{Short description|Computer simulation of life by the ecologist Thomas S. Ray}}
[[File:Tierra.png|thumb|upright=2|A running Tierra simulation]]
'''Tierra''' is a [[computer simulation]] developed by [[ecologist]] [[Thomas S. Ray]] in the early 1990s in which [[computer program]]s compete for time (central processing unit ([[Central processing unit|CPU]]) time) and space (access to [[main memory]]). In this context, the computer programs in Tierra are considered to be [[evolvability|evolvable]] and can [[mutation|mutate]], [[self-replication|self-replicate]] and [[Genetic recombination|recombine]]. Tierra's virtual machine is written in [[C (programming language)|C]].<ref>{{cite web|last=Ray|first=Thomas|title=What this Program is|url=http://tomray.me/pubs/doc/index.html#What|accessdate=3 January 2014}}</ref>  It operates on a custom instruction set designed to facilitate code changes and reordering, including features such as jump to template<ref>{{cite web|last=Ray|first=Thomas|title=Available instructions|url=http://tomray.me/pubs/doc/index.html#Idt|accessdate=3 January 2014}}</ref> (as opposed to the relative or absolute jumps common to most instruction sets).