Professor Don Bitzer: Father of PLATO discusses his work

In the twilight space between night and dawn that drowsy procrastinators know all too well, a student downs the last of his third cup of coffee before logging in to Compass for a course reading. His brow furrows as he peruses the PDF, then he finishes a reading quiz before collapsing on his bed.

The online learning system so integrated into his daily routine is the product of a series of systems descended from a design first developed at Illinois almost 20 years before the creation of the world wide web, called PLATO (Programmed Logic for Automatic Teaching Operations).

Illinois first developed PLATO as a means of extending learning to students in inner-city schools.

“Alarming numbers of students at the time were coming out of inner-city schools functionally illiterate,” PLATO creator and ECE Professor Emeritus Donald Bitzer (BSEE ’55, MSEE ’56, PhD ’60) said.

Bitzer returned to campus recently to speak at an event sponsored by the Academy for Excellence in Engineering Education called "Past, Present, and Future" about the development process behind PLATO. 

Illinois educators wanted to develop a way to bring learning to students over a network, allowing them to take virtual courses in a variety of subject matters and gain knowledge through the network that may not be otherwise available to them. PLATO was also the precursor to modern social networks, allowing students to contribute to a class discussion board and blog tool.

“All of the features you see kids using now, like discussion boards or forums and blogs started with PLATO,” Bitzer said. “All of the social networking we take for granted actually started as an educational tool.”

The university set up a committee to explore the concept in 1959, including engineers, psychologists, education professionals, and developers. However, the committee couldn’t reach a conclusion, and argued that the members’ areas of expertise didn’t overlap enough to agree on a proposal. Coordinated Science Lab director Daniel Alpert, who was reviewing the response before sending it on to the Dean of the College of Engineering Will Everitt, asked Bitzer if he agreed that it couldn’t be done.  He took a look at Alpert, grinned, and told him “I will have a proposal to you by next week.” 

Bitzer took the helm and started developing PLATO for the university’s ILLIAC-1 computer. He rigged ILLIAC to work with a television output, and started to program in the very first online courses. Bitzer developed a graphical TV output, a keyboard input system, revolutionary for the time because computers still mostly operated on punch cards, and an interactive learning simulation. The latter allowed the course to first present the user with material and then ask questions for the user to answer.

The first versions of PLATO ran directly off TV signals generated by the behemoth ILLIAC I.  To get PLATO courses into the schools, though, Bitzer had to find a way to distribute the images to remote terminals in a less expensive way.

Bitzer’s work on this problem led him in 1964 to invent the plasma display with Professor H. Gene Slottow and graduate student Robert Willson.  The key was to make a display that could show graphic images but had imbedded memory to reduce the communication demand from the computer to the terminal.  This would be easy with today’s technology, but memory in those days was composed of discrete parts and cost several dollars per byte. 

Others had tried making flat displays with imbedded memory for years, but drilling the holes to insert a resistor to create impedance between the pixels in the display caused the panels to shatter.

“Keeping an open mind on impedance, we realized that capacitance is an impedance for alternating currents,” Bitzer said. “This impedance could be introduced by placing the electrodes on the outside of the panel and driving the display with an A. C. source (100,000 cycles per second).  Thus, this panel became known as the A. C.  Plasma Panel.” 

The first display panels were made from thin microscope slide covers, which were placed on top of each other and stuck together at the edges with vacuum-sealing glue. Bitzer used a vacuum system to evacuate gas from the panel, but the borrowed vacuum system unknowingly had a leak which let in outside air gases such as nitrogen, turning the screen output pink instead of the predicted orange. 

The panel worked well and Bitzer’s team fixed the leak to build a better second panel, but when they turned the panel on with a perfect vacuum, it didn’t work at all because the nitrogen from the air leak turned out to be necessary for the machine’s memory to work properly.

“It’s the funniest thing,” Bitzer said.  “ If the first vacuum system would not have had a leak, it would have taken us longer to make a working plasma panel.  The new panel allowed a single telephone line to run 16 terminals as compared to requiring a television channel per terminal before. 

PLATO caught on like wildfire. The university built cable lines going from ILLIAC to various buildings on campus, Parkland College, and Leal Elementary School in Urbana At the grade school an M&M’s dispenser was hooked up to give the students candy when they completed lessons, and this system proved wildly popular, with students saving the M&M’s as trophies of their success.

Apart from his work on PLATO and the plasma screen, another intriguing but lesser known facet of Bitzer’s career was his work in Kharagpur, India in 1964.  After his work on PLATO, Bitzer worked as a visiting professor at the Indian Institute of Technology at Kharagpur in West Bengal, helping IIT become a world-class institution.  Bitzer lived with his family for nearly a year obtaining and installing a computer as well as advising the school on using the computer in their engineering school.  Living in the wilderness home near Kharagpur was an incredibly memorable experience for Bitzer and his family.

“I remember first finding out that there were cobras in my garage,” Bitzer said. “At first, I was creeped out! Later, however, I just stuck to my side to get in the jeep every morning and the cobras stuck to theirs.”

Bitzer has gone from strength to strength on a successful career in academia and engineering. He had started developing the plasma display during work on PLATO IV, and pushed it even further along with a student researcher who later became a significant ECE ILLINOIS alumnus in his own right, Larry Weber. Weber and Bitzer eventually turned plasma into a widespread television screen technology. The plasma screen displays on homeowners’ walls, now ubiquitous, can be traced back to the first orange-glowing PLATO terminals Bitzer’s team developed.

“As an undergraduate, the first time I saw the plasma display, I thought it was some professor’s pet project that would go nowhere,” Weber said, chuckling. “But after talking to Don, I got sucked in. If you’ve talked to him then you’ll know exactly what I mean. By the middle of my undergrad, I was absolutely convinced plasma was the way to go and I’ve devoted almost my entire career and the past 50 years to plasma since. Don’s work was amazing and I’m honored to be a part of it.”