1. A computer system adapted to execute a code, said computer system comprising: a processor configured to operate in a privileged mode and a non-privileged mode; a coprocessor adapted to operate in coordination with the processor; wherein the processor is adapted to: when operating in the non-privileged mode execute the code in accordance with a first set of instructions when a first value is stored in the coprocessor and execute the code in accordance with a second set of instructions when a second value is stored in the coprocessor; and when operating in the privileged mode following a first event, execute the code in accordance with an encoding of the first set of instructions when a third value is stored in the coprocessor and execute the code in accordance with the second set of instructions when a fourth value is stored in the coprocessor; and when operating in the privileged mode following a second event, execute the code in accordance with the first set of instructions when a fifth value is stored in the coprocessor and execute the code in accordance with the second set of instructions when a sixth value is stored in the coprocessor.