C64 Basic screen scrolling possible???

[RipX]

Hi guys,

I'm new to the board and am interested in learning some C64 programming techniqes. I have looked around and can't really find any information on whether it was possible to scroll the screen by x number of pixels using BASIC (I know that it is possible with 6502 ASM). I'm guessing it would require poking an address if it is possible, but it has been many years since i've even looked at BASIC. Any info on this would be great...perhaps an online reference or sample code etc ?? Many thanks in advance.

RipX

[RedWolf]

Hi guys,

I'm new to the board and am interested in learning some C64 programming techniqes. I have looked around and can't really find any information on whether it was possible to scroll the screen by x number of pixels using BASIC (I know that it is possible with 6502 ASM). I'm guessing it would require poking an address if it is possible, but it has been many years since i've even looked at BASIC. Any info on this would be great...perhaps an online reference or sample code etc ?? Many thanks in advance.

RipX

Hey RipX, welcome to the forum!

What you want would undoubtedly require use of assembly (though POKEs, etc.); no BASIC I know of has ever supported pixel by pixel scrolling control.  Are you talking about scrolling text?  Because if you're talking about graphics (which I suppose you're not), you can, of course, control every pixel in the BASIC graphics area (not sure how big it is on the C64) individually.

All my C64 programming books are packed away in boxes, so I can't really get to them easily at the moment.  Maybe someone else has an idea.  Sorry I can't help you more.

Benj

[RipX]

Hi RedWolf...

Thanks for answering...What I mean is that:

Code:

POKE 53281,0

Seems to directly POKE the addresses of the VIC Chip according to this site http://www.antimon.org/code/Linus/

The VIC
The VIC (the graphics chip) is very nice. The VIC has a lot of interesting bugs (or features, depending on how you look at it), which means you can create amazing effects that are unique to the C-64. It's all about learning about the hardware and learning how to use it to fit your needs, not just blindly following a specification document.

Most of these effects are achieved through well-timed modifications of VIC registers. That's one of the things are most important in demo program: to use perfectly timed code. Creating raster bars on the Amiga is easy: just put some values in the copper list. On the C-64, on the other hand, you have to change $d020 and/or $d021 at exactly the right time, or you'll get flickering bars.

The above code turns the page area black...So I was therfore wondering if I could use the same method to scroll the screen by setting a bit in the VIC that correlates to making it scroll!!

RipX

[RipX]

I have actually been able to get this to work...I have posted my code and link back here on my own forum at:

http://ripx.freeforums.org/viewtopic.php?p=14

I hope that this can be helpful to someone else

RipX

[RedWolf]

I have actually been able to get this to work...I have posted my code and link back here on my own forum at:

http://ripx.freeforums.org/viewtopic.php?p=14

I hope that this can be helpful to someone else

RipX

Awesome.  Congrats on figuring it out!  And thanks for sharing it with us.  It almost makes me want to try it myself on my C64 downstairs.

[RipX]

Cool... I'd love to know if it works on an actual machine - sadly I don't own one!!

RipX