Date   : Tue, 16 Jun 2009 15:14:58 +0100 (BST)
From   : chris@... (Chris Johns)
Subject: Black Teletext

On Tue, 16 Jun 2009, Ian Wolstenholme wrote:

> At the weekend I wrote a little routine which traps the OSWRCH thingy
> and changes any VDU code &80 into an &84.  Much to my surprise, it worked!
> So if I typed VDU &80,65 I would get a blue letter A etc.
>
> Except it doesn't work for the Teletext adapter, which must load the pages
> direct into screen RAM!
>
> Is there a way to trap any write to the Mode 7 screen RAM and do a similar
> fiddle?

Don't think so, but you could hook something to an event to check for any 
&80s and replace them by &84s. My first guess would be VSYNC, unless 
checking 1k of data every vsync is too expensive.
-- 
  Chris Johns <chris@...             >