André Bensoussan was a talented engineer who worked with Tom Van Vleck on the Multics operating system. They were tasked with creating a subsystem called the VTOC manager, which was essentially a virtual memory manager. André took on the challenge of designing, implementing, and testing this manager. He meticulously sat at his desk, drawing numerous symmetrical diagrams to ensure all the necessary information was captured. Despite some nervousness about the schedule, André eventually began writing code with pencil and paper. After ironing out a few typos, the code compiled perfectly and the VTOC manager worked flawlessly. André’s ability to accomplish all this with just a pencil was truly remarkable.
https://multicians.org/andre.html