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Subjectthis is a good answer indeed! thanks! [nt] Reply to this message
Posted byTerry Bogard
Posted on05/07/02 08:01 PM



> > Thanks, man, you are very kind, but unfortunately this info is not enough...
> >
> > Character Map Mode
> > Each character is 8x8. The screen is made of 40x25 characters
> >
> > Well, (8x8)*(40x25) is 320x200. Fine, that's the usable text area. But I guess
> > that the backgroud surrounding it is not considered here...
> >
> > Bitmapped Graphics Mode
> > HiRes Mode: 320x200 pixels, any one color per character-cell, and the
> background
> > color
> > Multocolor Mode: 160x200 pixels, 3 pre-selected colors, any one color per
> > character-cell, and the background color
> >
> > Again, this is the "work area". It would be enough, if the VIC-II wouldn't
> allow
> > to blit anything outside of it - which is not the case.
> > Play some tricky-programmed games, like Creatures 1 & 2 or Turrican (if my
> > memory serves me well), and you'll see sprites travelling right there, where
> > there shouldn't be anything...
> >
> > I want to know the resolution of the WHOLE C64 screen, not just the "normally
> > usable" part of it.
>
> Pixel-addressable space on the C-64 is 320x200 (in hires graphics/character
> mode) and 160x200 (in multicolor hires/multicolor character mode). There was
> also a VIC-II register that controlled "border" color (which was basically
> anywhere outside the 320x200 or 160x200 area), and you could set up a scan-line
> interrupt to change the register at certain scanlines, but pixels outside of the
> 320x200 area could never be affected by anything outside the border color
> register. The size of the border was actually a function of you monitor's
> horizontal/vertical size/height adjustments, nothing could be done from within
> the machine to change that.
>
> So what resolution you run your emulator at is all in personal preference. You
> can run any game at 320x240 (and have the border only at the top and bottom),
> and this is the resolution that I run at. You can run it at 400x300 (which will
> give you left/right borders, as well). Your choice, makes no difference.
>
> There was a "trick" to display sprites in the border area (which involved
> flipping the screen vertical height bit from 25 rows to 24 rows after the VIC
> had started displaying the 24th row, thus tricking the VIC into never turning
> off the sprites at the "bottom" (and top) of the screen), but this only allows
> sprites to be seen outside the borders, it doesn't affect the display resolution
> of the VIC chip at all, and you can't use vertical scrolling in 25-line mode
> without artifacts showing up on the top/bottom of the screen. Few (if any)
> games used this- AFAIK only demo coders used this "bug", because you could stick
> a sprite out there but no background graphics.
>
> The C-64 programmers reference manual has a section on sprites (Commodore called
> them "movable object blocks" or "MOBS")... if you read the section detailing
> sprite X and Y coordinates, you'll get an insight into how the VIC internally
> divvied up the screen coordinates, which is I believe what you are looking for.
>




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Entire Thread
Subject  Posted byPosted On
*c64 resolution(s?)  Terry Bogard04/25/02 08:24 AM
.*Re: c64 resolution(s?)  Lord Ashram05/08/02 06:47 PM
..*H res was 320 pixels...  Prophet05/24/02 03:12 AM
...*Re: H res was 320 pixels... *edited*  Jan_Klaassen06/02/02 06:09 PM
...*nopey  Lord Ashram05/28/02 00:08 AM
..*Great, thanks a lot! [nt]  Terry Bogard05/09/02 02:49 PM
.*http://roger.trideja.com/c64/ -(nt)  Trebor04/25/02 11:41 AM
..*uhm... not enough...  Terry Bogard04/25/02 01:00 PM
...*Re: uhm... not enough...  Shadow_fire05/05/02 11:00 AM
.....this is a good answer indeed! thanks! [nt]  Terry Bogard05/07/02 08:01 PM
...*Re: uhm... not enough...  Iron Man04/25/02 02:14 PM