The integrated electronics in a Minitel terminal has four functionally distinct parts:
* The subset visualization responsible for producing the TV images from the signals received by the Minitel or hit on his keyboard.
* The subset keymap loaded recognizes the keyboard and sends their code to the subset visualization and to the telephone line keys.
* The subset serial interface is responsible for providing signals to the DIN socket (computer peripherals) to devices.
* The MODEM (modulator-demodulator) that transforms internal digital signals Minitel. These various subsets are grouped on three printed circuit boards.
The keyboard of the Minitel is managed by an 8048 microprocessor at Intel. It is a circuit that performs several functions in one housing.
- The heart of the microcontroller: the central processing unit or CPU of 8 bits. - 64 bytes of RAM.
- 1 KB of ROM.
- An 8-bit timer counter.
- 27 lines of inputs / outputs.
Software integrated in the ROM 8048 provides scanning of 65 keys.
The keystroke causes the production of a code or a code sequence corresponding to the character indicated on this function. If two keys (or more) are simultaneously pressed no action occurs. One of these keys will be taken into account as soon as the other is released.
The 8048, two inlets / outlets will provide the determination of the key, is also responsible for the serialization code since there is no standard UART function integrated in the microcontroller, and the series is produced by the integrated software.
The connection of the keyboard unit is via a six-pin connector carrying the power, mass, and the RESET signal issued by the serial data 8048.
By early 1986, 1.4 million terminals were connected to Minitel, with plans to distribute another million by the end of the year. To reduce opposition from newspapers worried about competition from an electronic network, they were allowed to establish the first consumer services on Minitel. Libération offered 24-hour online news, such as results from events at the 1984 Summer Olympics in Los Angeles that occurred overnight in France. Providers advertised their own services in their own publications, which helped market the overall Minitel network. Others founded newspapers solely to create Minitel services.
By 1988, three million terminals were installed, with 100,000 new units installed monthly. The telephone directory received 23 million calls monthly, with 40,000 updates daily. About 6,000 other services were available, with 250 added monthly. France Télécom estimated that almost 9 million terminals—including web-enabled personal computers (Windows, Mac OS, and Linux)—had access to the network at the end of 1999, and that it was used by 25 million people (of a total population of 60 million). Developed by 10,000 companies, in 1996, almost 26,000 different services were available.
