Light Pens ... - test-drb@ccmp.vtda.org

18 Jul 2001

On Jul 17, 20:22, Richard Erlacher wrote:

...
  If the refresh memory is to support text and graphics,
 the pipeline must be
...
  two-forked. 
Not necessarily.  In a BBC Micro, for example, the 6845 is essentially
generating a stream of pixel addresses, since what's stored in the screen
memory is the bitmap of the character, not the character code.  That's how
you mix text and graphics on the same screen.  When text is written to the
screen, the OS looks up the bitmap(s) of the character(s) and writes the
individual pixels to screen RAM.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York