Issue link: https://iconnect007.uberflip.com/i/461203
38 The PCB Design Magazine • February 2015 DAn: When I was a very young man, way back in the taped artwork days of the 1970s, I was a program coordinator (a fancy name for expeditor) at Rockwell's Maine Electronics in Lisbon, Maine. One of my programs was the Burroughs Scientific Processor (BSP) created by Burroughs Corporation, based in Paoli, Pennsyl- vania. We were building very high-tech 14- and 16-layer boards for this program. We were told that these BSP computers were so powerful that the first one was already "running" the airport in Narita, Japan. Now, this was 1975, mind you. The only computer I had ever seen was being installed in a glass room at the company. I was walk- ing around tracking my PCBs with a pen and clipboard and I had no idea what "running an airport with a computer" even meant. By the way, I did get a chance to see a BSP system being built. It was quite an impressive sight, especial- ly since they had slimmed it down to three re- frigerator/freezer-sized units. I remember being amazed that something that small could run an entire airport! And this was the first time I had ever heard of impedance. All I knew about it was that these two guys, Bob McQuiston from Burroughs and Andy Yenco from Maine Electronics, spent weeks building literally hundreds of boards, in- venting ways to measure this impedance thing and then throwing out most of them. It would break my heart to carry all of these great look- ing boards to the scrap heap day after day. Finally, one day I heard Andy let out a whoop and slap Bob on the back (there was no man-hugging back then). They had done it! They had finally built and measured some boards with the right controlled impedance. That was 40 years ago, so I'm thinking that may- be I saw the first controlled impedance boards feature coulmn by Dan Beaulieu and Bob Tarzwell BOB AnD ME Controlled Impedance: A Real-World Look at the PCB Side