1. A method of controlling access to a dataprocessor, the data processor being arranged to execute a plurality of requested function commands, the method comprising: determining if a requested function command conforms to a set of parameters, the set of parameters being derived from previously executed function commands; in response to determining that the requested function command does not conform to the set of parameters, controlling the data processor to halt the execution of the requested function command; and controlling the data processor to subsequently resume execution of the requested function command in response to one or more resumption conditions being satisfied.