2010-03-22 (updated 2021-09-04)
Started in the 1960s at the University of Illinois, it ran until the 2000. Donald Bitzer is called "the father of PLATO". Other PLATO systems continued running until 2006. CDC (Control Data Corporation) was the manufacture and developed many applications for the PLATO. They purchased the commercial rights to the PLATO system in 1976.
PLATO saw many of the first online forums, message boards, online testing, email, chat rooms, picture languages, instant messaging, remote screen sharing, and multi-player online games.
PLATO terminals were interactive. When most home PC users think of terminals today, they think of type a line, then pres ENTER, then something happens, after a pause. This is not how PLATO terminals worked. Every key press could cause a response fairly instantly. It was as if the keyboard was connected directly to the mainframe.
PLATO (and many other educational computer teaching systems) was developed out of the need to deal with the massive increase in students seeking higher education in the USA starting with the Servicemen's Readjustment Act of 1944 (the G. I. Bill). The GI Bill guaranteed higher education and the possibility of 1 year of unemployment in the field of the chosen education for all people in US military service. This kicked off an interest in higher education when most people in the US had not previously considered it important. US industry had already seen a massive increase in factory production due in part to computerized automation supplementing the widespread mechanical automation. Computers were soon explored as a supplemental learning tool on most higher education campuses. Sputnik kicked this exploration into high gear for fear that the US was falling behind the USSR in science and education. Its no wonder so many early games had sci-fi and war based plots and were programmed around mathematical and logical programming, these were the very reasons the computers were even available to the students. Thanks to Cold War politics, the Army-Navy-Air Force funding pool provided the initial grants for PLATO. In 1967 the National Science Foundation took on the responsibility of funding the system.

PLATO was not the first or only system of its type. In fact the first demonstration of the PLATO system was done on the ILLIAC I computer that it quickly replaced. A key to success of PLATO over other systems was allowing students to proceed and review the lessons at their own pace, especially when this involved skipping lessons for things they already knew. Other systems were very linear and required the student to rehash the same information every time they ran the program, even if they only needed to improve a in a small section of knowledge. Another improvement was it's multiuser capability (introduce with PLATO II). This very expensive system could be shared by many students at once (or administrated while students continued to used it); increasing the volume of 'customers served'. The final bit of advantage was the TUTOR language introduced with PLATO III. TUTOR allowed anyone to create lessons (see PLATO in Africa section below). This meant many times more teaching tools could be added without additional effort by specially trained staff. The teachers could design their own lessons. The users in industry could create lessons for students that trained them in bran new technologies; information that wouldn't be available in text books for at least a year (probably many years, maybe never due to intellectual property egest). Industry was able to get trained employees at a fraction of the time, effort, and cost of training them after hiring them. Additionally, the lessons were a supplement to retrain existing employees. Actually the idea of TUTOR was students could add lessons. Instead of a one student tutoring one other student at a time, they could tutor many. (The other benefits were a pleasant surprise).

Plasma display, video memory, 512x512 resolution, vector graphics, bitmap graphics, raster graphics, multiple photographic quality color backgrounds (they were actual microfiche projections), TV out, pointing device (infrared touch screen display), local peripherals, 4–16 voice music synthesis, and speech synthesis. A PLATO IV terminal more than met the minimum requirements for a gaming system. Btw, this was by 1972. Once this terminal was created, Donald Bitzer declared the PLATO system to be a success and PLATO IV terminals when into full scale production. All around the world, communities could create a 'university' for themselves in exchange for an air-conditions room, minimal staff and $13,000. Existing universities could expand their classes.
The PLATO IV terminals were manufactured by Magnavox. Oddly, there was never a PLATO terminal created for the Odyssey². Was this never even considered?

This is still available to users today. There was no official PLATO V system. Microcomputers with Intel 8080 CPUs were used as terminals instead of the $12,000 PLATO IV terminals (they could also be rented for $1000 a month). Special applications were downloaded to these cheaper terminals to make it emulate or simulate a PLATO IV terminal, using the local CPU (PLATO IV terminals had local Video memory which could be abused as local general memory, but no local CPU). This was a forerunner of Java. While special Intel 8080 microcomputers were made for this purpose, the software was also ported to other PCs. This array of microcomputer terminals and software to support provide PLATO access came to be known as "PLATO V".
Today, there is a dual opteron Tyan Thunder K8W production machine running DtCyber on Suse Linux 9.1 for AMD64. DtCyber is a CDC Cyber mainframe emulator. NOS is an operating system for the CDC Cyber mainframe. Cyber1 is a PLATO emulator for NOS. Lets review this lesson: Cyber1 (PLATO emulator)←NOS (operating system)←DtCyber (CDC Cyber mainframe emulator)←Tyan Thunder K8W (AMD64 based microcomputer). Something could go wrong with this setup so their is a duplicate backup system, which runs on a different computer: Cyber1←NOS←DtCyber←Mac G5 running OS X Panther. This system can be accessed with any terminal emulator for text only display or a specialized PLATO IV terminal emulator if sound and graphics are desired. This system currently has 1284 registered users (2008-09-21), which means PLATO probably has more terminals now than it was when it was officially supported :) You can find out more about accessing PLATO through this system at www.cyber1.org/. They also host older CYBIS and NovaNET systems, two branches/competitors of the PLATO system that are still being maintained today.

The PLATO system was very popular in South Africa in the early 80s. Madadeni College at one time had over 100 PLATO IV terminals. These were primarily used by Zulu students from remote areas to learn math and science skills. Most of the campus did not have electricity and had only a few unreliable phones. The PLATO IV terminals were often the only means of outside contact. The terminal room was also the only one on campus with air-conditioning (required for the equipment), so all-in-all it was a popular hangout. Even though the vast majority of arriving the students had never seen any modern technology (any technology, not even flush toilets), they were able to proficiently use the terminals to start learning within an hour. A few students even learned the TUTOR language and made their own teaching programs. A course of lessons by a student was used to teach the Zulu language allover the world, since the PLATO system was internationally networked.

It would be fascinating to find out what roles games played in teaching these students how to use the PLATO terminals (since games were no longer outlawed at the time, and were a popular teaching tool to familiarize students with the PLATO system and teaching all kinds of activities using games is an aspect of traditional Zulu culture). Also, were there any game created by these students? I think, most certainly yes. But, how to find records of them?

Industry in Africa also took an interest in the PLATO system and it was used to train employees.

While a major concentration of PLATO terminals were at Madadeni College, the were scattered through out Africa.

At the time CDC was the driving force behind PLATO. They failed to recognize that the home, educational, and business markets were shifting their focus to microcomputers rather than terminals and mainframes. This lead to financial problems in North America even though their African subsidiary was doing well (mainframes with terminals in Africa made much more sense than microcomputers at the time, and still do in some areas). But, also devistating was the idea that businesses should pull out of South Africa because of human rights issues. Despite their heavy involvement in humanitarian endeavors and their commitment to social corporate responsibility, CDC was not a non-profit group. Since CDC's subsidiary, and all the technology necessary to operate PLATO, were based in South Africa, they had to abandon the whole continent. It was a huge blow to education and technology in Africa. And also to gamers and gaming on the continent.

PLATO stands for Programmed Logic for Automated Teaching Operations.

"Cyber1.org. No, it is not beautiful, but neither was the Millennium Falcon." - from Cyber1.org

Systems with graphical PLATO terminal emulators:
Atari 8-bit (this cartridge rocks! much better than using a text terminal)
Windows
Mac OS X
*nix (Linux, UNIX, SunOS, BSD, Solaris, etc)