Date   : Tue, 03 Mar 2009 00:01:11 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: New Screen Modes with ARM7 Co-Processor?

Ian Wolstenholme wrote:
> At the back of my mind I remember something from the Advanced
> User Guide or suchlike which allowed you to program your own
 
At <http://mdfs.net/Apps/Graphics/NewModes> is code to
produce 80-column 4-colour and 40-column 16-colour screen modes,
ie RISC OS MODE 8 and MODE 9, by redefining the font and character
spacing.
 
It was inspired by an article in Micro User in about 1990 that
used both screen buffers and switched between them on each
horizontal sync to double the resolution. However, that required
continuous, fiddly and fast interupt code and custom screen
writing code.
 
Plus, of course, it wouldn't work on the BBC - my only computer at
that time.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation
  See http://mdfs.net/Software/BBCBasic/Windows/ProgTips