Videotex
|
|
Videotex is a system for sending of pages of text to a user in computer form, typically to be displayed on a television.
Videotex in its broader definition can be used to refer to any such service; including the Internet, bulletin board systems, online service providers and even the arrival/departure displays at an airport. In a more limited definition, it refers only to two-way information services, as opposed to one-way services such as teletext. However, unlike the modern Internet, all traditional videotex services were highly centralized.
| Contents |
History
The first attempt at a general-purpose videotex service were created in the United Kingdom in the late 1960s. In about 1970 the BBC had a brainstorming session in which it was decided to start researching ways to send closed captioning information to audience. As the Teledata research continued the BBC became interested in using the system for delivering any sort of information, not just closed captioning. In 1972, the concept was first made public under the new name Ceefax. Meanwhile the General Post Office (soon to become British Telecom) was researching a similar concept since the late 1960s, known as Viewdata. Unlike Ceefax which was a one-way service carried in the existing TV signal, Viewdata was a two-way system using telephones. Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones. Not to be outdone by the BBC, they also announced their service, under the name Prestel. ITV soon joined the fray with a Ceefax-clone known as ORACLE.
In 1974 all of the services sat down and created a standard for displaying the information. The display would be a simple 40x24 grid of text, with some graphics characters for constructing simple graphics. This standard was called CEPT1. The standard did not define the delivery system, so both Viewdata-like and Teledata-like services could at least share the TV-side hardware (which at that point in time was quite expensive). The standard also introduced a new term that covered all such services, teletext. Ceefax first started operation in 1977 with a limited 30 pages, followed quickly by ORACLE and then Prestel in 1979.
Prestel was somewhat popular for a time, but never gained anywhere near the popularity of Ceefax. This was due primarily to it delivering much the same content, yet requiring the user to pay for the terminal (today referred to as a set-top box), a monthly charge, and phone bills on top of that (even local calls are paid for in most of Europe). Although Prestel's two-way features (including e-mail) were interesting, the end-users appeared to be unwilling to pay much for such a service, not as much as it cost to run it at least. In the late 1980s the system was re-focused as a provider of financial data, and eventually bought out by the Financial Times in 1994. It continues today in name only, as FT's information service. A closed access videotex system based on the Prestel model was developed by the travel industry, and continues to be almost universally used by travel agents throughout the country.
North America
Interest in the UK trials did not go unnoticed in North America. In Canada the Department of Communications started a lengthy development program in the late 1970s that led to a "second generation" service known as Telidon. Telidon split the data flow in two, using both the TV signal and the telephone. The TV signal was used in a similar fashion to Ceefax, but used more of the available signal (due to differences in the signals between North America and Europe) for a data rate about 1200 bit/s, while using a low-speed modem on the phone line for menu operation. The resulting system was rolled out in several test studies, all of which were failures.
Apparently unwilling to learn from these problems, a number of US based media firms jumped on the videotex bandwagon in the early 1980s. Unlike the UK however, the FCC refused to set a single technical standard, so each provider could choose what they wished. Some selected Telidon (now standardized as NAPLPS) but the majority decided to use slight-modified versions of the Prestel hardware. Rolled out across the country from 1982 to 1984, all of the services quickly died and none remained after another two years.
The primary problem was that the systems were simply too slow, operating on 300 baud modems connected to large minicomputers. After waiting several seconds for the data to be sent, users then had to scroll up and down to view the articles. Searching and indexing was not provided, so users often had to download long lists of titles before they could download the article itself. Furthermore, most of the same information was available in easy-to-use TV format on the air, or in general reference books at the local library, and didn't tie up your phone line. Unlike the Ceefax system where the signal was available for free in every TV, many U.S. systems cost hundreds of dollars to install, plus monthly fees of $30 or more.
For many years, the Prodigy online service did use NAPLPS to send information to its users, right up until it turned into an Internet service provider in the late 1990s, but avoided calling itself a videotex service so that it would not be tainted by all the business failures linked to that name. Also, by the time Prodigy belatedly went online in 1987, personal computers had become well-entrenched in American homes. Unlike the early European videotex providers back in the 1970s, Prodigy was able to skip the intermediate step of persuading American consumers to attach proprietary boxes to their televisions.
Minitel
With the French Minitel system, unlike any other service, the users were given an entire custom designed terminal for free. This was a deliberate move on the part of France Telecom, which reasoned that it would be cheaper in the long run to give away free terminals and teach its customers how to look up telephone listings on the terminal, instead of continuing to print and ship millions of phone books each year.
Once the network was in place, commercial services started to sprout up, becoming very popular in the mid-1980s. By 1990 tens of millions of terminals were in use. Like Prestel, Minitel used an asymmetric modem (1200 baud for downloading information to the terminal and 75 baud back).
Bell Canada even tried to introduce Minitel to Canada as Alex in the early 1990s, but the service quickly failed. A combination of high prices, poor services and competition from a growing body of online services doomed the system before it was able to gain a foothold.
A very successful system was started in São Paulo, Brazil, by then state-owned Telesp (Telecomunicações de São Paulo). It operated from 1982 to the mid-nineties; a few other state telephone companies followed Telesp's lead, but each state kept standalone databases and services. The key to its success was that the phone company offered only the service and phone subscriber databases and third parties - banks, database providers, newspapers - offered additional content and services. The system peaked at 70 thousand subscribers around 1995.
CEPT
The Germans took the CEPT1 concept and expanded it so it was somewhat more flexible, the resulting standard was called CEPT2.
In Germany, the system was named BTX (Bildschirmtext [Engl: "screen text"]).
After that the French went one step further and developed CEPT3 that would be used for their popular Minitel system.
None of the CEPT standards used high resolution graphics.
Comparison to the Internet today
Many people often confuse videotex with the Internet. Although early videotex providers in the 1970s encountered many issues similar to those faced by Internet service providers 20 years later, it is important to emphasize that the two technologies evolved separately and reflect fundamentally different assumptions about how to computerize communications.
The Internet in its mature form (after 1990) is highly decentralized in that it is essentially a federation of thousands of service providers whose mutual cooperation makes everything run, more or less. Furthermore, the various hardware and software components of the Internet are designed, manufactured and supported by thousands of different companies. Thus, completing any given task on the Internet (such as retrieving this article from Wikipedia) relies on the contributions of hundreds of people at a hundred or more distinct companies, each of which may have only very tenuous connections with each other.
In contrast, videotex was always highly centralized. Even in videotex networks where third-party companies could post their own content and operate special services like forums, a single company usually owned and operated the underlying communications network, developed and deployed the necessary hardware and software, and billed both content providers and users for access.
Nearly all books and articles from videotex's heyday (the late 1970s and early 1980s) seem to reflect a common assumption that in any given videotex system, there would be a single company that would build and operate the network. Although this appears shortsighted in retrospect, it is important to realize that communications had been perceived as a natural monopoly for almost a century — indeed, in much of the world, telephone networks were then and still are explicitly operated as a government monopoly. The Internet as we know it today was still in its infancy in the 1970s, and was mainly operated on telephone lines owned by AT&T which were leased by ARPA. At the time, AT&T did not take seriously the threat posed by packet switching; it actually turned down the opportunity to take over ARPANET. Other computer networks at the time were not really decentralized; for example, the private network Tymnet had central control computers called supervisors which controlled each other in an automatically determined hierarchy. It would take another decade of hard work to transform the Internet from an academic toy into the basis for a modern information utility.