Re: Commodore BTX Modul

From: Nicolas Welte (
Date: 1999-10-06 15:55:37

Richard Atkinson wrote:
> Hmm, just received this in the post. Says 'bildschirmtext' on the case -
> I'm guessing that means teletext. What exactly is it, and what does it do?

Don't know what teletext is. BTX=Bildschirmtext is an early German
online service based on the CEPT standard, similar implementations exist
at least in France and Austria, don't know about GB. You had to dial
into the service with a modem or acoustic coupler at the enormous speed
of 1200 baud down- and 75 baud upload speed.

> Or rather, how to I get it to do what it's supposed to do? There's a lot
> of ports and what looks like a pass-thru port for the power supply.

There were two versions of the module, I only have version two. This has
three DIN connectors on the back: 7 pin modem connector (I think this is
some current loop interface), 8 pin analog RGB connector and 8 pin C64
style composite/separate video connector. The module is capable of doing
at least 640x200 resolution with 4096 colours, but I think it was quite
restricted to some sort of character set based graphics. Still the
output is quite nice, especially in RGB mode. My module's composite
output sucks, there is some sort of interference pattern.

If the C64 is powered on with that module, it will display a startup
message with the module version number on both the C64 and module video

> PCB inside contains 4K of SRAM and an EPROM of unidentified size, plus a
> Philips SAA video chip of some kind and some PAL colour encoding
> circuitry. There's a large number of discrete devices in there too and
> another 40 pin DIL IC, so perhaps it has its own processor.

My version two module has an 6803 MCU with another 68xx support chip, I
guess some SRAM, 32k Eprom, and a SAA video chip with another 64k DRAM.
Some discrete stuff for video and modem interfacing is also there.

BTW, the module was developed and manufactured by Siemens, Commodore
only sold it under its name.

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