Biological Computation

The Never-Ending Story    ◾    279

the beginning of execution) to the write head (which the program posi-

tioned at aer the template nop-A, nop-B). At the end of the loop (aer

copying the whole program), the h-divide command is executed and

causes the program in the new memory region to turn into an indepen-

dent organism. e experimenter using Avida denes the probability

that h-copy will misbehave, and, instead of copying the command it is

supposed to copy, a random command will be copied into the descen-

dant. is creates mutations.

Note how Avida’s machine language uses the nop commands, whose exe-

cution has no eect, to seek memory locat