1. A memory controller operable to control a memory, said memory being operable in a plurality of modes, said memory controller comprising: memory interface logic configurable to interact with said memory in each of said plurality of modes; and memory mode change logic operable, in response to a memory mode change request instruction specifying a predetermined one said plurality of modes being issued by said memory interface logic to said memory, to request said memory interface logic to be configured to interact with said memory in said predetermined one of said plurality of modes and to prevent interaction between said memory interface logic and said memory until said memory interface logic confirms that it is configured to interact with said memory in said predetermined one of said plurality of modes.