We remember PLATO because it pioneered so many things we now take for granted as well as creating one of the very first online communities. It did this while the Internet was merely a tool for scientists at a few universities and government facilities, some twenty years before it took off among the general public.
PLATO was devised before the microprocessor so all terminals were online with a large mainframe computer. The UofI's own system had about 1,000 terminals and many hundreds were sometimes in use at one time. Yes, big companies like banks, insurance companies, and airlines had large networks at the time too. But their interactivity was limited to someone entering a request of some sort, pressing send or enter, and a second or two later a response pops up. On PLATO, every keypress got the full attention of the system before it even appeared on the terminal screen. That's a lot of computing!
The developers of PLATO realized that a graphical display was needed. Most terminals in those days were alphanumeric only. Existing graphics terminals were very expensive. So they set about to devise a custom terminal. One problem to overcome was the fact that graphics terminals usually need memory to represent every dot on the screen. Even without color or grayscale that was very costly at the time. Alphanumeric terminals display numbers and letters as dots but they don't store the dots in memory; instead they only store the character codes and continually feed them to a character generator (a lookup table memory chip) to retrieve the dot patterns needed to feed the video screen. A graphical display can't take this shortcut. So the PLATO folks invented the PLASMA DISPLAY panel. The great advantage was that individual dots could be turned on and off and will stay that way. No memory required. PLATO used a 512 x 512 display which was very high resolution for the time. The university contracted with Owens-Illinois, the glass company, to make the plasma displays for PLATO. PLATO's screens displayed in a nice, soothing orange color against a black background. These displays are the forerunner to today's plasma televisions and UofI collects royalties on some of the plasma display patents. One of the PLATO people recently won an Emmy award in this regard.
Because the plasma display was a clear glass plate, many terminals were equipped with a microfiche film projector which projected pictures onto a screen placed behind the plasma panel. A compressed-air mechanism, under control of the PLATO computer system, selected the correct image. The plasma display could then be used to point to and label parts of the film picture. This was very useful in medical and other fields where a real picture was needed.
Most terminals were equipped with TOUCH SCREENS for students to select something by pointing. Criss-crossing invisible infrared light beams were used although some later terminals used a different system.
Foreign language instruction was accomplished with an external AUDIO UNIT which utilized large, LP-sized magnetic disks which could play audio tracks under program control and also record student's responses. A compressed-air mechanism similar to that of the microfiche selector moved the record/playback head across the disk.
Each terminal had a connection on the back to which external equipment could be connected and data sent to/from under program control. Besides the audio device, there was a "Votrax" VOICE SYNTHESIZER, and a multichannel MUSIC SYNTHESIZER known as the "Gooch Box" after its inventor.
PLATO developers devised the TUTOR language to write lessons in and it offered powerful features for this purpose including ways to judge student answers and give appropriate feedback and help. Router programs told students which lessons they needed to take and allowed communication with instructors. Generally PLATO lessons supplemented rather than supplanted classroom instruction.
Among PLATO's innovations were these things we now take for granted: Email (called personal notes or Pnotes), online discussion forums (called notesfiles), online live chat (called Term-Talk and Talk-o-matic), gaming. Oh yeah gaming. This was a very big thing and some people stayed up all night playing. Star Trek games and Dungeons and Dragons were popular. Back in a day before there was even "Pong" people were playing sophisticated computer games, emailing, chatting live, and participating in forums covering every topic imaginable. But besides the technical innovation the most remarkable thing was the sense of community that formed with people who only knew each other online. As Control Data sold systems all around the world many were linked for email and the forums so there was a growing community online and this was well before the popularity of the internet or the brief flowering of computer bulletin boards.
Recently, some folks became concerned that much of the important innovation of PLATO has been overlooked by history. Books are being written. And a few folks have actually resurrected an actual working PLATO system. Instead of a roomful of "big iron" it runs on a PC. The PC runs the Linux operating system which in turn runs a emulator program which simulates the large Control Data mainframe computer. Everything above this level is genuine; the real deal: The Control Data operating system called NOS and then the actual PLATO software on top of that. So it's not a simulated PLATO system; it's a real one.
However, because Control Data had sold the name PLATO separately they can't call it that but use the name CDC came up with later on: "Cybis" The name of their system is "Cyber1" A terminal emulator program has been devised which allows a Windows, Mac or Linux computer user to simulate a PLATO terminal and connect to the Cyber1 PLATO...oops...I mean the Cyber1 "Cybis" system over the internet. For more information visit Cyber1's web site.
MY PLATO PHOTO PAGE is just my small contribution to show how things were back in the day.