Personal Computer Museum, Canada's Videogame Museum

Telidon / Teleguide Terminal

Telidon / Teleguide Terminal
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Release Date: 1/1/1984
Manufacturer: Electrohome
On Loan From: Lance Squire
Before the Internet took off with the World Wide Web, access to interactive information was available with the Telidon system. Using a standard phone line, the Telidon would communicate with a host machine and allow for advanced graphics (at the time) and interactive information to be delivered directly to the terminal.

The graphics language is called the North American Presentation Level Protocol System (NAPLPS) and was the first videotex software to employ alphageometric technology.

Funded originally as a government project, the Teleguide project sank as quickly as the funding dried up but some of the technology was acquired by Bell and made it into their Alextel terminals, many of which are still in use today. This machine is an important part of Canadian technology history and gives a glimpse into how things might have been.

User Comments
Arnold Hooton on Wednesday, May 2, 2018
I have an Apple II with the Telidon board that I used in the early 80's. I have all the manuals as well. I'm trying to find out how many were sold and how many may be left. I used my system to conference between Apple and Westinghouse Corporate in Pittsburgh Pa. I've contacted both Apple and Ross Video [the buyer of Norpak] and neither have any information regarding the Apple II telidon board.
James Bruce Lyttle on Monday, July 10, 2017
I worked on this project under the insightful leadership of Patrick Anthony at Electrohome in Kitchener, Ontario. In fact, I wrote the EGT-04 manual (and still have a copy somewhere). The protocol was developed by Canada's Communications Research Center. It was part of early efforts to bring online shopping, banking, and learning into the home. Its main innovation was relative addressed geometric codes that could send true graphics (not just character renderings) through existing slow media, such as telephone lines and the Vertical Blanking Intervals of television signals. Although Canadians were innovative enough to invent and implement this system, they were too naive to protect it. With a few subroutines added, AT&T/Bell applied for and got a patent on our protocol, which they now called the North American Presentation Level Protocol Standard (NAPLPS - later called North American Presentation Level Protocol Syntax and occasionally North American Presentation Layer Protocol Syntax). People announcing their "Sceptre" terminal at the Videotex '83 Conference reported that it cost about US$1200 to make, which was on a par with Electrohome's costs. But the American Bell's deeper pockets allowed them to list the product at about US$900 and sell it at US$600. Electrohome's Telidon terminal, which was selling at about $1400 Canadian, was thus squeezed out of the market and the "Computer Graphix" department was effectively dispersed. I went back to school for three university degrees and moved to the USA as a university professor, until retiring last year in Duluth, MN. Over time, media became faster and faster and, with the introduction of the World Wide Web, NAPLPS' ability to code graphics efficiently ceased to matter. The whole project seems to be just a memory, now. (
Justin on Thursday, December 29, 2016
Yes, ALEX (and ALEXtel hardware) was based on NAPLPS and was one of the descendants of the Telidon project. ALEXtel was made to look like Minitel because that was the world leader in videotex, but the data exchange did not follow Minitel's protocols at all. Videotex protocol usage broke down along strict national/regional lines, and died out altogether before interoperability was achieved.
Maury Markowitz on Monday, November 9, 2015
Did Alextel really support telidon? I though they were nothing more than re-badged Mintiel terminals?
James Alexander on Wednesday, July 18, 2007
I remember using these on a few occasions in the early 80's (83 or 84 I think). They could be found in a few public places, shopping malls, hotels etc. Last time I saw one was in pickering town center. Unlike todays internet kiosks, telidon was free to use.
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