Book excerpt: Much commercial work on organic synthesis relies heavily on computer-aided-design. This teaching package demonstrates in a clear and concise manner how such CAD works by allowing the construction of synthetic routes from a target molecule. Its purpose is to teach how computers may be used to design organic syntheses and it is loosely based on the much more sophisticated LHASA programme, available on larger computers. However, its advantage over LHASA is that it makes parts of the design process visible to students. Enough practical chemistry hints are given in the accompanying manual for the work done on the system to be put in context of practical organic lab sessions. The software is written in BASIC and runs on the BBC Model B or Master series.