PROVIDING A MASTER DEVICE WITH SLAVE DEVICE CAPABILITY INFORMATION

In a system having a master device coupled to a slave device by means of an interface, wherein a function of the master device includes downloading a control program to the slave device, an apparatus for providing the master device with capability information corresponding to the slave device has hardware for reading the capability information from a predefined portion of the control program, and hardware for storing the capability information for use by the master device during a communications operation with the slave device. An encoding scheme for the capability information permits new functions to be added without having to re-encode pre-existing information corresponding to pre-existing slave devices. The capability information is encoded as a first vector and a second vector. A new function that is supported by a new slave device is added to the first vector when the new function is not supported by any pre-existing slave device. Default values are provided for pre-existing first vectors, to indicate that the new function is not supported by the pre-existing slave devices. Similarly, a new function that is supported by all pre-existing slave devices but not supported by a new slave device is added to the second vector, with appropriate default values provided for pre-existing second vectors. En un sistema que tiene un dispositivo maestro acoplado a un dispositivo secundario, por medio de una interfaz, en que una funcion del dispositivo maestro incluye descargar un programa de control al dispositivo secundario, un aparato para suministrar al dispositivo maestro con la informacion del la capacidad que corresponde al dispositivo secundario, este aparato comprende: un elemento para leer la informacion de la capacidad desde una porcion definida previamente del programa de control; y un elemento para almacenar la informacion de la capacidad para su uso por el dispositivo maestro durante una operacion de comunicaciones con el dispositivo secundario.