Re: ASCII art / FIGlet

["John B. Matthews" <nospam@nospam.com>]

In article 
<1gt0xmj.yb6hh5b8wyt6N%email@DELETE_THIS.luddite.no-ip.com>,
 email@DELETE_THIS.luddite.no-ip.com (Simon Williams) wrote:

> Craig Bower <to.email.me@post.a.request.message> wrote:
> 
> <snip>
> 
> > Try this instead:
> > 
> > 110 GR : X = 0
> > 110 FOR I = 8192 TO 9210
> > 120 POKE 1024 + X , PEEK ( I )
> > 130 X=X+1
> > 140 NEXT I
> > 
> > It's still not even remotely pretty ASCII art at the
> > end,  but it'll get you started with more complex
> > displays.
> 
> Kinda neat, depending on the input image, but it seems to have some
> oddball side effects like disabling scrolling. Even so, I managed to
> waste an hour viewing hires images in lores... I must be a masochist or
> something... ;-)

This side effect is due to the code overwriting the so-called screen 
holes: non-displayed text memory reserved for each slot.

$0478-$047F 
$04F8-$04FF 
$0578-$057F 
$05F8-$05FF 
$0678-$067F 
$06F8-$06FF 
$0778-$077F 
$07F8-$07FF

Typical firmware uses this RAM as a scratchpad to record control 
information such as cursor position, mouse location, etc.

See _Apple_Monitors_Peeled_, <http://www.turbo-2.com/apple/> page 
15-16, for a more thorough discussion.

You can avoid the screen holes by skipping values of X in which bits 
four through seven are set.

-- 
John
jmatthews at wright dot edu
www dot wright dot edu/~john.matthews/