[Coco] hardware scrolling

[Simon Jonassen]

Hey again Nick !

I forgot to answer the Q about SemiGraphics....

Yes i have dabbled a little... You can scroll the screen in the "broken"
semi graphics mode.... The one where you can mix hires (only 7 bits) and
text/SG blocks !!

More on that later...

/Simon :-)

 

-----Oprindelig meddelelse-----
Fra: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] På
vegne af Nick Marentes
Sendt: 28. oktober 2013 10:19
Til: CoCoList
Emne: [Coco] hardware scrolling

So, in order to create an endless scroll, like Super Mario or Scramble, you
would need to scroll the 42 byte window till it reaches its limit then you
would have to do a software copy of the region back and repeat the scroll.

You would need to draw the new graphics just off screen from the incoming
edge.

If I'm reading this right, the bottleneck will be the block copy to achieve
the loopback.

You are playing with the restriction of 64K. Unless you allocate more RAM
for video display to scroll across into (reposition the start of screen).
Maybe move across to a 2nd 6K page, copying the disappearing edge back to
the start point so when you reach the end point, you can shift the entire
screen back to the start and repeat the process.

... That's if I'm understanding your technique right.

Since you can do split screen, you won't have to copy the entire screen but
a smaller band across the screen. This buys you cycles.

Have you explored your technique in a semigraphics mode?

Nick



--
Coco mailing list
Coco at maltedmedia.com
http://five.pairlist.net/mailman/listinfo/coco
-----
Ingen virus fundet i denne meddelelse.
Kontrolleret af AVG - www.avg.com
Version: 2012.0.2242 / Virusdatabase: 3222/6286 - Udgivelsesdato: 27-10-2013