Date   : Tue, 10 Aug 2004 01:51:05 +0100 (BST)
From   : Pete Turnbull <pete@...>
Subject: Re: Oddity with display

On Aug 9 2004, 21:22, Jules Richardson wrote:
> On Mon, 2004-08-09 at 20:35, Chris Priest wrote:

> > When the beeb powers up, I get the usual BBC Computer 32K, Acorn
DFS,
> > except... it's black lettering on a white background!

> Check jumper S26; in one position (or no jumper at all) it causes the
> hardware to produce normal video, and in the other it produces
inverse
> video.

If there's no jumper, check the underside of the board for a short wire
there.  The original Ferranti ULA and the later release of the Video
Processor work as Jules describe, but the first release of the VidProc
didn't, and there was a wire under the board to set the polarity of the
signal (and no jumper link).  It may be that someone has fitted an
early VidProc and not done the modification, or replaced an early one
with a late one and not undone the mod, or omitted the jumper.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York