Sigma 3 - Life Changing

In 1972 the NASA Cardiovascular Lab got a Xerox Data Systems Sigma 3 minicomputer. This turned out to be life changing for me. I left any semblance of circuit design and focused entirely on computing for the rest of my career.

This “minicomputer” filled a 30 x 30 room with a false floor and air conditioning — a far cry from what we now think of as a minicomputer. What made it so great for me is that I could load cards into its card reader myself and get run after run without waiting for the overnight turnaround on the NASA Univac 1108’s.

The Sigma 3’s operating system was RBM — Realtime Batch Monitor. I actually spent three weeks at the XDS facility on Century Boulevard in Los Angeles. I really had to bargain to get NASA to approve my education trip. I had to stay at my in-laws in Palos Verdes Estates (with Kathy and the kids), borrow my brother in law Chris’s Austin Healey Sprite, and forgo a per diem. A good deal for what I gained.

I learned machine language for the first time. I learned about fielding interrupts and preserving state. I learned about interfacing to external devices. This set me up for so many great things further in my career.

Using the computer was life changing. I ported VECTAN (the vectorcardiogram analysis program) to the Sigma 3. We had a data collection system in the lab that digitized vectorcardiograms from test subjects during live testing. It wrote its data in long records on 7-track digital tape. VECTAN on the Sigma 3 and on the 1108 needed 9-track data. I wrote a program called PASTOR to quickly convert 7-track to 9-track.

My computing roots in large batch processing were expanded, converted and fully established in these smaller, more versatile machines.