|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|
Because we can!
Also, CEPT is an already defined standard, we can use. There's hardware out there, but it can also be emulated using cheap Wifi modules and 320x240 TFT displays. Since everything is page oriented and page selection happens via a numeric keypad, this might be a cool function for a future badge.
What can I do?
First of all, you can play with the terminals provided.
If you want to do something more technical, you can set up an TCP server speaking the CEPT protocol and I can make the terminals connect to it. I'll also publish the modem source code as soon as it's ready.
We'll bring probably one terminal connected to the POC network
We will have a dial-in number for the POC network which speaks v23 as well as the data link layer protocol for error-free connectivity.
If you want to have your own service, set up a TCP-server which speaks CEPT and I'll be able to hook that up.