Conditional jumps consitute free will
The ability of a system to perform conditional jumps when confronted with changing information gives it the potential to make free decisions.
For example, a computer may or may not "jump" when it interprets the instruction "proceed to address 9739 if the contents of register A are less than 10." The decision making that results from this ability frees the machine from being a mere puppet of the programmer.
The Simons argument
"The main program and the subsidiary routines are written, and incorporated into the computer system, well before the particular parameter changes are monitored. It is thus essential for the computer to be able to decide on a course of action according to particular circumstances. The provision for doing this is established in the computer program, but the way that the provision will be exploited by the computer cannot be known until the particular combination of circumstances occurs.
It is thus the conditional jump facility in the digital computer that provides it with its decision capability--and with, therefore, its potential for individual autonomy. It is the computer, not the programmer, that selects a particular course of action in changing circumstances" (G. Simons, 1985, p. 119).
"[T]he decision facility in the modern digital computer is already immensely sophisticated: in large systems, it is not fully understood by any single human programmer--but the computer understands! If a programmed capacity for decision making constitutes free will, then emerging computer life-forms have free will in abundance" (G. Simons, 1985, p. 120).
References
Simons, Geoff. 1985. The Biology of Computer Life: Survival, Emotion and Free Will. Boston: Birkhauser.