Avram's Past / Technology

Rotterdam 1969-1974: The Thoraxcenter

Towards the end of 1968, I accepted a position at the Thoraxcenter in Rotterdam. My task was to create and run the computer dept.  It was actually two depts.  One was part of the medical school at Erasmus University and the other was part of the  Dijkzigt University Medical Center.  Accepting the position was both and easy and difficult decision.  It was easy to accept an offer that would mean relocating to Holland, a country I had visited before and liked.  I was pretty negative about the USA at the time, particularly because of the Vietnam War.  And to make matters worse, Ronald Reagan was governor of California.  I was employed  by UC San Francisco Medical School  and worked at the Langley Porter Institute so I actually work for the state  But it was hard to leave Joe Kamiya who was not only my boss, but also my mentor and friend.  Furthermore, while I was very interested in our work in brainwave bio feedback (I designed some of the first equipment to do brainwave bio feedback)  and the idea of designing systems to diagnose and treat heart patients was not nearly as interesting.

Professor Paul Hugenholtz MD, was the founder and Executive Director  of the Thoraxcenter (Thoraxcentrum) .  He was a Dutch cardiologist who had spent many years working at  Boston Hospital and doing some experimental work with people at MIT.  Paul’s vision for the Thoraxcenter included fully integrating computer technology into the care of patience.  This was  a pretty advanced concept in 1968.   Paul would call me in San Francisco early in the morning  from Holland to try to convince me join his staff. I eventually agreed.  I was to report to Jerry  Russel who was an american bio-technologest.   Jerry also had experience in using computers in cardiology.  He had decided  use computers from Digital Equipment Corp and ordered two PDP-9s for the Thoraxcenter.    I already knew how to program  the PDP-7 and sometime before I left Joe’s lab, we had also gotten a PDP-9.  So this was a familiar  base for me.   I don’t remember what exactly what happened but sometime soon after my arrival, I ended up reporting directly to Paul Hugenholtz.    Paul was/is and amazing man.  Here is a link to a pretty detailed interview with him about his life.  Paul, thought me much and I will always be grateful to him for his support and coaching.  The day I arrived at the Thoraxcenter, I was greeted by his assistant, Arianne van der Klooster, who became my wife of 25 years (we are no longer married but still close)  and the mother of my three children.

This was my first management  position. I had just turned 24 years old.  I also had not graduated from college and was about to fill a position on the academic staff.   I think by the time I left some five years later to immigrate with my family to Israel, there were over 30 people working my group and and held a position that was something between an assistant and associate professor.  We accomplished much both in terms of the development of  computer technology and in terms of cardiovascular medicine. It is almost funny to think about the technology we had to use and how we improvised so much which is really the main point of this blog post.

Let me start by describing the basic set up.  We had two nearly identical PDP-9s.  The PDP-9 had an 18 bit word length (today computers have either 8, 16, 32 or 64 bit word lengths).  The maximum memory was 32,000 words. To put into bytes (8 bits) which we now commonly use to describe computer memory, it had 72,000  bytes (72kb).      Most of the photos I take on my iPhone are about three times as large as the total memory of the computer.  We had no disk memory.  We had a small tape unit which had a capacity about equal to the main memory.  We did not swap programs.  All the software had to be in main memory.  We got really good at writing very tight programs in assembly code as you can imagine.  One of the computers was used for our real time Intensive Care Unit (ICU) Monitoring System.  The other was used for program development.  Only one programer could work on that computer at a time.  The programing computer was also used as backup to the mission critical ICU system.  To facility that ability to switch, we had a small bus switch which would move all the peripherals  we used for the clinical system to the backup/programing computer.

I think the computer system monitored heart rate, blood pressure, temperature  and breath  I don’t remember if we were able to monitor arrhythmia.  I doubt it.  We actually got the raw signal in for the EKG, blood pressure and breath.  We used a Digital to Analog Converter which was multiplex to sample four signals for six patient and from that we computed the key values we monitored Not only could we provide the nursing staff with continuous instantaneous values but the could set alarm thresholds. We were also able to provided graphs so that trend lines could be seen.   There  were six patients on line, I believe.   The displays at the nurses desk were TV monitors turned on their sides.  We used a head per track video disk to create the images and text. This desk  was actually developed for the television industry.  But the craziest things was the keyboard.  At first, we used rotary  phone to send commands from the nurses to the computer.  In other words, the nurse would dial a command.  The computer would monitor the signal from the phone and count the pulses.  Later, we built a specialized keyboard using keys that were designed for elevators.  The company that developed the specialized equipment for us was Mennen Medical. ( I would later work for that company in Israel where I was able to commercialize some of the work I had done at the Thoraxcenter. I also joined the staff at the dept. of cardiology, Tel Aviv Medical School as Adjunct Associate Professor.)   Later, we  wanted to increased  to look at other aspects of the EKG such a t-waves but we did not have enough computing power.  It was then that I ordered a PDP-15 which was the successor of the PDP-9.  But I treated it in a way like a microprocessor.  I just got a small version without any peripherals and we created a high speed connection to the ICU computer system. It was the beginning of my love of networking computers.  I had a special love for the PDP-15.  When I was still working at Langley Porter, I found that there was a design problem with the PDP-9 which made it difficult to use for real time programing (it had to do with the interrupt structure).  I modified the micro code of PDP-9 to fix the problem and Digital took that change and applied it to the PDP-15.

We then got one of the very first PDP-11s. I think it might have had 32kb of memory.  We used it to develop a system for the catheterization lab.  That system was later licensed to Mennen Greatbatch.  We also developed software for some of the first work in echo-cardiogram as well as creating a computer simulation model of the heart.  It would take the computer a whole day just to have one heart beat I think.

I have been working with computer for 45 years.  The capabilities have grown by something great than 50,000 times.  I remember making circuits with just one transistor, a few resistors and a couple of capacitors.  If you look at the evolution of biological intelligence and compare it with computer intelligence, there is just one conclusion that I can make:  That in my life time we will go from a single cell to a human capability. And then what?  More about that some other time when I explain why the universe is the way it is.

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