A speech recognition module for a personal digital assistant comprises: a module housing designed to engage with an accessory feature of the PDA, such as an accessory slot; a microphone for receiving speech commands from the person; and a speech recognition system. A corresponding electrical speech command signal is communicated to the portable computing device, allowing control of the operation of a software application program running on the portable computing device. In particular, menu items can be selected for generation of a diet log for the person, for example during a weight control program.