Date   : Mon, 25 Feb 2002 15:15:39 +0000 (GMT)
From   : Sprow <rsprowso@...>
Subject: Re: Circuits involving a SAA5050?

On Mon, 25 Feb 2002, Kris Adcock wrote:

> For several years now I've been maintaining a RiscPC system with a teletext
> decoder card in it.

[snip]

> I'm looking to build my own
> 'serverely simplified' version of the card. Using an SAA5050 chip seems to
> be an obvious choice

Getting the timing right on an SAA5050 looks a real pig of a job.I'd have
thought it was easier to get a high speed ROM and put the character set in
it yourself then have 2x1k banks of RAM.

1k is the one being output by video engine which blindly looks up the
result in ROM (with some latches in the state machine to take into account
when you're in double height/blink/etc mode)

1k is one that the Risc PC can write to over the podule bus

The two RAMs can then be switched between during a VSync flyback.Quite an
interesting project I think.

Re: the TV license debate,as I understood it you need a license if you own
equipment *capable* of receiving broadcast TV regardless of whether you
had an aerial plugged in.Depending where you live,you can quite often get
a watchable picture with no aerial at all - which wouldn't look too good
in court!

Sprow.