In recent times an ever increasing amount of manufacturers use, and abuse, the very flexible specifications of the human interface (USB-HID) devices. This is an useful fact if there is some missing feature in the provided software, something you want to remove or there isn't any support at all. Let's see how to identify structures, protocols and develop our own software for these scenarios, using the new calculator HP Prime as example which, like the majority of modern devices makes use of this specification