[Coco] hardware scrolling

[Simon Jonassen]

Yup....

There is more than that....

Overscan, multicolour, vertical scolling, zooming....

$ff22 is truly a multipurpose register when timed correctly....

/Simon :-)

 

-----Oprindelig meddelelse-----
Fra: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] På
vegne af Rogelio Perea
Sendt: 25. oktober 2013 22:23
Til: CoCoList for Color Computer Enthusiasts
Emne: Re: [Coco] hardware scrolling

Impressive!. Yet another thing the CoCo was not supposed to do :-)


-- RP


On Fri, Oct 25, 2013 at 2:29 PM, Simon Jonassen <simon at roust-it.dk> wrote:

> well now...
>
> after countless experiments and headaches, hardware scrolling of a 6K 
> hires bitmap via $ff22 and some raster trickery is entirely possible 
> on a coco II !!!!
>
> so the vdg isn't entirely dead afterall... she's hiding more tricks
yet....
>
> http://roust-it.dk/coco/realvsp.mpe
>
> above link is a video of a real coco II and my laptop with Xroar 
> scrolling the 6k bitmap in hardware...
>
> the routine is only updating every 6th frame, so it can be much faster....
> it can also be made to scroll further with a few more lines of code....
>
>
> /Simon :-)
>

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