Norbert's Emulators

Teletext Reader for the Commodore 64

At a Commodore meeting in Vienna a visitor said, that it would be nice to read teletext pages on a Commodore 64. I thought so too, and wrote a teletext reader, but probably based on a different concept, than originally imagined by that C64 fan. Teletext is made up of (almost pure) text pages with 24 lines and 40 columns, and it is broadcast by many TV stations via the television signal in the so-called vertical blanking interval lines. The contents offered in these pages are mainly news, weather, TV schedules, etc.

To read the teletext pages on a Commodore 64 you would have to build some hardware to extract the data from the TV signal and feed it into the C64. This would also be a really interesting Retro project in itself, but for my simple reader I used an alternative method. Many TV stations offer their teletext contents also on their web sites for reading them in the browser. So, I wrote C programs to download all the teletext pages of a specific TV station to your Windows PC and convert them into files readable by my C64 teletext reader program. Each teletext page will then become one file for the C64. You can then copy all these files and the reader program to an SD card and take your time to read them on the Commodore. The pages are identified by 3-digit numbers, which you can enter in the C64 reader and select the page with the "Return" key. The function keys offer some simple navigation functions, like going back to the last page, etc.

The program can be downloaded as an zip file here: teletext.zip.

The archive contains Windows programs you run on the Windows command line. It will then download and convert all the teletext pages of the selected channel to a C64 readable format and store them as files in a directory called "pages". This takes about 20 seconds to 10 minutes. Then the teletext reader program for the Commodore 64 is copied to this "pages" directory also, and you are ready to take this whole directory over to your Commodore 64, e.g. on an SD card. Have a look at the "readme.txt" file in the archive for the details.

If you want to write your own downloader for your favorite TV station's teletext, you find the format of the C64 files to be generated below:

        Position (hex)    Contents
        -------------------------------------------------------------------------
        $0000-$0001       Load address (low byte/high byte). Always has to be
                          0x00/0x40 (i.e. address $4000).

        $0002-$03c1       40 x 24 bytes for the text of the page (ASCII and
                          special characters).

        $03c2             Separator. Always has to be 0x00.

        $03c3-$0782       40 x 24 bytes for color and width/height information
                          for each character of the teletext page. The 8 bits
                          of each byte are interpreted as "hfffwbbb", with:
                          h   ... Double height indicator (0=normal, 1=double)
                          fff ... Text color in C64 color code format (0-7)
                          w   ... Double width indicator (0=normal, 1=double)
                          bbb ... Background color in C64 color code format (0-7)
        -------------------------------------------------------------------------
	

Below you see some screenshots of the result:

Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader
Norbert Kehrer's Commodore 64 Teletext Reader Norbert Kehrer's Commodore 64 Teletext Reader