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February 2010 Archives

UIUC ECE396 PLATO IV Terminal Restoration Project Today I received an email from Donald Ziems, a student of Professor Lippold Haken. Turns out Haken's ECE 395 class at the University of Illinois Urbana-Champaign has a team of students restoring an ancient PLATO IV terminal as a class project (cool!). Donald pointed me to the class wiki where they're tracking the progress of the project, including a bunch of photos and a PDF of the "PLATO IV Operation Manual".

An ancient screen shot of the CERL PLATO system's welcome page from 1975.

PLATO system welcome page, Valentine's Day 1975

Long before Google was customizing their home page to celebrate observances, holidays, and such (like they are doing this week with the 2010 Winter Olympics), at a time when Larry and Sergey were still too young for kindergarten, PLATO's welcome page would be customized for various holidays like Christmas, 4th of July, Valentine's Day, Halloween, and Thanksgiving.

UPDATE - 22 March 2011 -- If you're reading this it's probably because of Slashdot's article that appeared today. For more information including more screen shots and update on the issue, see a blog post added today on Google's patent and the related PLATO history.

It appears that Internet Explorer 6.0 for Windows may not work well with this site. I don't have the budget to add support for IE6, especially when IE7 and even IE8 are out on the market and are free.

I am hearing that IE8 works fine but have not tested it yet myself. If you are a Windows user I highly recommend IE8 if you want to use this website. You can download IE8 from here:

If you see broken pages, tons of centered text, the right half of the page missing, stuff like that, please email me or comment below and let me know what operating system, version, browser and browser version you're using. Thanks.

UPDATE 2/13/2010: I went through and cleaned up the CSS and HTML and made it all XHTML 1.0 compliant, and now the site should look reasonably legible for IE6 and IE7 users.

Aaron Woolfson has for the past five years undertaken an amazing project: to acquire and restore -- not just clean up, but restore to original factory specifications -- a variety of original PLATO terminals from the 1970s. He's traveled all over the country, picked up parts here and there, and has even had custom parts made.

On January 20, I finally got to meet Aaron. We converged on the Computer History Museum so the museum folks could see a real working PLATO V terminal. The plan is to have, on hand at the conference about half-a-dozen PLATO terminals up and running and connected to the service. Attendees will be able to try out the terminals and check out original PLATO applications including thousands of educational lessons ranging from anthropology to zoology, as well as the notesfiles, TERM-talk, and of course, PLATO's legendary multiplayer games.

Here are some photos of the terminal Aaron showed off at the museum:

PLATO V terminal restoration

What's especially cool is that Aaron has hacked together an interface such that the terminal thinks it's connected to a 1260-bps serial line, but in fact, is connected to the Internet which it then converts into the old 1260-bps serial signal. For the conference, he's building little interface boxes for each terminal such that all you have to do is plug the terminal into an ethernet cable connected to the service on the Internet and you're all done.

Back on January 13th, I participated in an 80-minute interview with Jon Udell. In case you missed it, and if you are new to the history of PLATO, it's a good starting point to learn some of the history and find out why PLATO is relevant today.

The interview was published on the IT Conversations site. Here's their description:

This year marks the 50th anniversary of PLATO, the pioneering educational courseware system that was also, for certain lucky individuals at certain universities, a preview of an online culture -- one that many others would not encounter for decades to come. In this conversation with host Jon Udell, PLATO historian Brian Dear recalls what it was like to experience an early distribution of a future that was, and in some ways still remains, unevenly distributed.

Here is a link to the IT Conversations interview page for "PLATO Turns 50" where you can play or download the interview. It's also available on iTunes as a podcast!

Recently I received an email from David Dennis, a former PLATO user from Illinois who over the years has shared with me numerous anecdotes. This one was one I'd not heard before, where he describes what he believes might have been the first instance of a "denial of service" (DoS) attack on a computer network.

If there is one thing I've learned over the years, never make an absolute claim of "first" when it comes to anything computer-related, because as soon as you do, someone somewhere will come out of the woodwork with proof of an even-earlier first. So, I eagerly await the onslaught of "no way, I saw a DOS attack years earlier!" comments. But in the meantime, here's a neat story from 1974.

Some quick explanation of terms before I quote the email. First, he's recalling an incident that took place at CERL, the Computer-based Education Research Laboratory, at the University of Illinois Urbana-Champaign. "TUTOR" is the name of the programming language on PLATO. "Author mode" refers to a level of system privileges on PLATO that all authors/developers had. "Went back over to uni" means he went back over to University High School, located across the street from CERL. (Old joke: Why did the Uni High student cross the road? To get to CERL.)

Okay, here goes. From David Dennis:

As far as I know, I'm the first person to have created a DoS of a room full of PLATO terminals deliberately. Systems people could of course kick anyone out they wanted, and "operator wars" had existed for years, but those tended to be consensual attacks on each other. What I did was I heard about a new command called the "external" command in TUTOR, or 'ext'. Specifically, one of the music kids was saying how if you didn't have a device attached, an ext command would cause your terminal to lock up and have to be powered off. Remember that powering off was discouraged, due to always-concern over flaky power to the plasma panels.

The other piece of this was they had rolled out the external command for everyone in the fall of 1974, after it having been only in use by the Music project. This meant that every user account on PLATO was set to defalt "can accept ext commands." Default on.

If you recognize default enabled from any firewall work you'll immediately recognize the trouble...

Anyway, I heard this and immediately thought of how a room full of annoying users could be locked up at once. My little 13 year old brain wanted to see a room full of users all be locked up at once.

So, I wrote a little program that sent exts to everyone within a range of site numbers, waited til I was over at CERL one morning, and let er rip.

It worked as advertised, 31 users all had to power off at once, great mayhem in the classroom, site monitors notified. No logging of course, I was never detected. Quietly left the room, went back over to uni.

Accessed the site displays I knew of from author mode, and looked up other sites around town or the country, and tried sending them some ext's too. Was delighted to see mass posting on notesfiles about a locking out they were experiencing.

Soon some systems guys figured it out, probably a combination of common sense and maybe looking in some sort of logs, though I was never prosecuted or even approached, so I have to think to this day it was undetected. A few weeks later the ext command was withdrawn from 'open all' and a while after that was redeployed, this time with the default set to OFF. As it should have been all along. :)

So was there ever a DoS on a networked system prior to 1974 ? Im sure there had to be, but at least for the moment I'm claiming it !

This is a classic example of how things typically go with software, only this is an example from 1974: release a system to the users, and they will find bugs and vulnerabilities the developers weren't aware of or assumed were harmless. Make changes, release a revised system, and so on. Over time, this is how the PLATO system became more robust and secure.

UPDATE 2/14/2010 -- Welcome, slashdot. Er, one moment while I put out the fire that you're causing with my web server. :-) Let me provide a little more detail on the TUTOR -ext- command, how it worked, etc. Here is the actual page from PLATO's online help system for the -ext- command:

ext command documentation

The -ext- command was relatively new in 1974, indeed, it may have been brand-new. It was intended so that you could have your PLATO IV terminal connected to an external peripheral device and control that device using a serial connection. Note how the manual says "only 1 -ext- per second may be sent to another station." Heh, in those days, one per second might be enough!

UPDATE #2 - 2/14/2010 Below is the note on =announce=, the System Announcements notesfile, from 1/2/74, announcing that a change had ben made to the -ext- command (perhaps, not sure, due to the exploit above):

-ext-         Note 1

1/2/74         12:32 am CST         andersen / s

The two argument -ext- command (ext data,station) now checks if the other station wishes to recieve -ext- commands... as with the talk option an author may specify that he wishes to recieve -ext-'s from anyone, from his course only, or not at all..

The -ext- command returns the system variable *error* = -1 if the data was sent or = 0 if not

The one-argument -ext- command is not affected

Welcome to the PLATO History blog. This is a direct continuation of the What's New page from the PLATO People website which has been documenting the progress of my book on the history of the PLATO system. That page was always a blog of sorts, with updates starting around 2002, though the site itself began in late 1996 (my book has taken a very long time to develop, indeed).

The PLATO People website will stick around but any new information will primarily wind up here on the PLATO History site as we go forward.


Learn more about the book:

The Friendly Orange Glow: The Story of the PLATO System and the Dawn of Cyberculture, by Brian Dear

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