1. A module attachable to data terminal equipment, comprising: a first storage for storing an application-specific program; a first processing unit for executing the program stored in said first storage; a first bus through which an execution result from said first processing unit is transferred; and a first communications controller for transmitting to the data terminal equipment the execution result transferred from said first bus to said data terminal equipment, wherein said data terminal equipment outputs, from an internal output part, the execution result provided from said first communications controller.