Re: ][+ Video card question(s)

[dempson@actrix.gen.nz (David Empson)]

In article <35cf38$u1@crcnis1.unl.edu>,
Greg Berigan <gberigan@cse.unl.edu> wrote:
> 
> Well, I do have sitting on some disk a program which achieves 80 column
> text on a ][ without the need of a card.  It achieved this through
> attaining DHR graphics, but had much flicker and was only readable when
> the screen was steady (not scrolling).  It would work on any Apple II.
> The program was of German origin.

I've now been told how this is done (thanks, Paul).

It works by swapping quickly between the two hi-res graphics pages.
Page 1 has all of its colour set bits (bit 7) set to 0, and page 2 has
all of its colour set bits set to 1.  This causes a half-dot shift on
the image on page 2, and effectively gives you double the horizontal
resolution, but with big pixels.

It will flicker quite badly, and half the image will disappear while
the program goes off to do anything else.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand