Just One C64 about question

[José Pereira]

Hello.

 

Just this one:

"C64 Fine Scrolling is only on Bitmap Mode or also on Colour Map Mode?"

 

 

Yeah, o.k. I need to put a 2nd one:

"C64 have the two: Horizontal and Vertical Fine Scrolling?"

 

 

 

Thanks.

 

Greetings.

José Pereira.

[Heaven/TQA]

both are right... otherwise scrolling games would not be possible and you would have color clashes if color ram would not be shifted, too...

 

the only difference to Atari is that on our side we have color-clock resolution (so "pixel"-size) while on c64 it is always "highres"-pixel scroll resolution.

[José Pereira]

Thanks.

 

But as we say here in Portugal:

"Talking is like eating Cherries... "

( A MonCheri now... Anyone have one (or two...)?)

 

I usually saw C64 Horiz. Sccrollers using 38Chars Wide Playfield.

Like first Black, Playfield Scrolling (38Chars wise) and last Charr Black.

What is the way of that?

 

Char0, Charr 1->38, Char ???

It's to have Scrrolling only using 40Chars? First on OFF when new arrives?

 

 

 

And on A8 what is norrmally the Formula in Horizontal Scrollers?

 

 

 

 

What is A8 better looking? In my opinion 48Chars wide (42 visible), but on this will I lost/need 48Chars in each Line?

 

 

 

 

 

Thanks.

José Pereirra.

[TMR]

It's to have Scrrolling only using 40Chars? First on OFF when new arrives?

 

Yup, the C64 pulls the borders in to mask the data that is arriving and leaving for both horizontal and vertical smooth scrolling - it goes to 38 columns or 24 rows depending on direction. In 38 column mode, the 39th column is the one arriving at the right and the first goes off at the left - column 40 is never actually displayed so more optimised scroll routines ignore it and save a few cycles here and there.

 

And on A8 what is norrmally the Formula in Horizontal Scrollers?

 

When the horizontal scrolling is enabled in regular or narrow playfield, the A8 starts grabbing more data for each character or bitmap line - wide playfield is already wide enough that the edges of the scrolling are masked by being outside the television's display. For a regular playfield with horizontal scrolling, each line is 48 bytes wide so if the screen starts at location 10000 (as a random example) the second line will be at 10048, the third at 10096 and so on.

 

What is A8 better looking? In my opinion 48Chars wide (42 visible), but on this will I lost/need 48Chars in each Line?

 

Personally i tend to use standard width playfield if i can, but it's all a matter of taste and what resources are available.

Edited April 28, 2010 by TMR

[PeteD]

The only problem with standard width on the A8 is there's no border to mask any PMGs going off/on the sides. The C64's border masks everything including the sprites so you never get that problem. You can mask them in software of course of if you've got a P/M spare mask with those.

 

*edit*

Also, the PMGs only fill standard width so if you're using them quad expanded for background underlays you'd have to design levels with that in mind.

 

 

 

Pete

Edited April 28, 2010 by PeteD