|Description||We'll bring Bildschirmtext back to live as a more distributed and more playable system|
|Persons working on|
|Tags||retrotechnology, onlineservices, retrocomputing|
What is Bildschirmtext?
In the 1970s and 1980s advances in microelectronics made it possible to build fairly cheap terminals connected to the telephone network. Since those terminals were either dedicated machines or modules integrated into your TV set, they didn't have to deal with the low resolution of NTSC and therefore provide high resolution images. The German BTX, for example 480 content pixels per line, and 250 lines. This allows for 40x24 lines of 12x10 pixel characters as well as an additional status line. There is support for user defined characters as well as 32 colours out of a palette of 4096. User defined characters are also available in colour! This is the lowest level of CEPT.
On the telephone side of this, there was a simple V.23 modem, using the 1200 bps channel for downstream, and the 75 bps channel for upstream. Later devices supported faster transmission rates as well as 64 kbit ISDN.
There are multiple standard character sets.
Character set G0: ($20-$7f)
Character set G1: ($20-$7f)
Character set G2: ($40-$7f)
Character set G3: ($20-$7f)
There are also 93 DRCS characters
Use the "ss2" command, then select a charactter from G2, then have your main character.
Example: "ss2"Hu gives you an ü.
|$08||APB||Active Position Back (left)|
|$09||APF||Active Position Forward (right)|
|$0A||APD||Active Position Down|
|$0B||APB||Active Position Up|
|$0D||APR||Active Position Return (to left most column, keep line|
|$12||RPT||Repeat last character n times. n in next octet|
|$18||CAN||Erases line right of cursor|
|$19||SS2||Single Shift to G2 (for combining characters)|
|$1B||ESC||Escape for longer commands|
|$1D||SS3||Single shift to G3|
|$1E||APH||Active Position Home (cursor to home position)|
|$1A||DCT||Makes the terminal talk|
Commands from the terminal
|$13||INI||Initiator, the sextile key used to start entering a page number|
|$1C||TER||Terminator, the octothorpe key used to end entering a page number|