by Barbara Black

Build your own computer — that was the assignment for 120 students in the computer engineering course COEN 417, and it opened their eyes to how this magic machine works, and what can prevent it from working.

Their professor, Dr. Mohamed Nekili, said, “The students were just amazed. The project consumed them totally.”

Four employees spent six months building a prototype of the computer, called TalKit, and writing a manual. The students had to take it from there, using the fundamentals they had studied in class. They did their work in a lab equipped with four Tektronix logic analyzers, four channel scopes, 80 printed circuit boards and nearly $10,000 in components. At the heart of TalKit lies a Motorola MC68000 microprocessor, driving ROMs, static and dynamic memories and some peripheral ports.

Professor Nekili said that not only did the project give the students a deeper understanding of the theory they learned in their courses, but they had to pass a definitive test: whether they could record their voice and play it back on the computer.

When the student’s work was successful, Nekili said, “the sound was properly sampled, properly routed through the data bus, properly stored in memory, the different chips properly addressed and selected, and finally the instructions were properly executed by the microprocessor.

“Just imagine the student’s impression upon smooth playback by the machine!”

If they didn’t get a successful playback, however, they had to go back to their model, take it apart and see where they went wrong — a genuine learning experience.

Nekili is planning the second version of this project for the fall term. He said it will involve “less wiring and more thinking” — a response to the students who became so obsessed by building their computer that they spent an inordinate amount of time on the mechanics.

However, the idea of the course won rave reviews from many of the students who participated. One student remarked afterwards, “I did find the labs to be extremely useful in understanding the workings of a microprocessor system. And it was actually enjoyable when our results turned out as expected.” Another said, “I think that this lab was incredibly interesting because it actually put all of the theory learned in class into practice ... It was a great experience.”

Professor Nekili added, “Special thanks go to [part-time instructor] Chris Taillefer for the excellent laboratory manual which was able to catch step-by-step the amazing experience of building one’s first computer and his close supervision of students, to [technician] Guy Gosselin for the professional experience that allowed the designer team not only to anticipate many of the obstacles to come but also to suggest elegant ways of overcoming them, and to [Director of Academic Facilities] Henry Kovalcik for making sure the team remained on the right track and the project up-to-date.”

A version of this article by Sophy Khwaja appeared in the Engineering and Computer Science magazine.