BBC Micro user-port interface

The recent interest in so-called ?intelligent? computer interfaces in no way suggests a decline in the need many users have for a simpler system, enabling them to perform output-only control activities with the help of a wellproduced but inexpensive interface device. I have noticed, for example, that the emphasis placed on control applications in technology syllabuses makes practical experience of the basic principles involved almost essential to a sound understanding of this part of the course.