Date   : Sun, 07 Sep 2003 09:59:27 +0100
From   : Sprow <info@...>
Subject: Re: newbie question

In article <006a01c374ee$22cb67a0$0100a8c0@...>,
   Bob Devries <bdevries@...> wrote:
> Sprow said:
> > However,before we go pulling chips out,it's not just something obvious

[nothing obvious]

> I believe that there's something amiss in th programming of the line size 
> in
> the registers of the 6845, or the 6845's access to the ram is faulty.
> Without a logic analizer, though, I can't tell.

I remember fixing a machine with functional but weird video which was the
74LS283 which couldn't add up.However that it occurs in modes 0-7 that
wouldn't make sense since in mode 7 the 6845 doesn't do much.

If you wrote a little program to fill the screen memory with &FF for each
mode this would confirm if the 6845 can't get at the RAM or not.

Other than that,dunno,
Sprow.