An isochronous processor includes a state register, a functional unit, a control module, and an activation unit. The state register includes an arm buffer and an active buffer. The functional unit performs a transformation operation on the data stream in response to an active value of the control parameter obtained from the active buffer. The control module updates the arm value of the control parameter in the arm buffer in response to control instructions. The activation unit detects a load event propagating with the data stream and transfers the parameter value from the arm buffer to the active buffer in response to the load event. During this transfer, the control module is inhibited from updating the arm buffer.