Date   : Tue, 26 Feb 2002 18:34:22 -0000
From   : "Chris Thornley" <C.J.Thornley@...>
Subject: Re: Circuits involving a SAA5050?

Hi,
http://www.qsl.net/zl1vfo/teletext.htm
As some information on register organisation of the chip etc also BBC
hardware or Advanced use guide has some information in it. Why don't you
use a dedicate teletext chip and feed data by i2c bus? DO you wish to
use the device to generate texetxt pages or receive them?

Why don't you use Mode 7 on your arc and output the RGB information
through an encoder into your TV set. I won't be supprise if the chip is
connected to the CRTC controller chip in the BBC.

Chris

-----Original Message-----
From: owner-bbc-micro@... [mailto:owner-bbc-micro@...]
On Behalf Of Kris Adcock
Sent: 26 February 2002 10:47
To: bbc-micro@...
Subject: RE: [BBC-Micro] Circuits involving a SAA5050?



> -----Original Message-----
> From: owner-bbc-micro@... 
> [mailto:owner-bbc-micro@...]On Behalf Of Michael Borcherds
> Sent: 25 February 2002 19:50
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] Circuits involving a SAA5050?
>
>
> > For several years now I've been maintaining a RiscPC system with a
> teletext
> > decoder card in it. The card is being used to produce an
> 80x25 screen of
> > text as a composite video signal. Now, I need to replace
> this card, mostly
> > because the card has a TV tuner in it, and the property
> where the computer
> > is based does not have a TV licence. So, I'm looking to build my own

> > 'serverely simplified' version of the card. Using an
> SAA5050 chip seems to
>
> Why not rig up a serial/parallel link to a BBC B and use its composite

> video output?
>
> cheers,
>
> Mike
>
> (well if you will post to a BBC list :))))

My main reason for posting here was that I figured here would reside the
foremost experts on BBC innards. Yes, I'd thought of using an entire
Beeb - it's just that that is quite a lot of hardware which I wouldn't
be using.

Looking at the BBC B circuit diagram again ... I still can't see what
else is helping the 5050 produce the text. Anyone know?

Cheers,

Kris.