[CSDb] - User Forums - Screen limits

You are not logged in - nap

CSDb User Forums

Forums > C64 Coding > Screen limits

2005-10-26 07:50

HCL

Registered: Feb 2003
Posts: 717

Screen limits

Once when i got myself a C= monitor, I made some tests to see what the actual limits were. Keeping in mind all the bugs i left in Royal Arte, after this i would never have to leave any visual bugs because of not seing them.

But now in EMU-age, the same horrible bugs appear again in many demos. Vice only shows 272 x 384 pixels, and people appearantly start to think that's the way to go. And it suxx big time!

So when i found my old screen tests yesterday, i thought maybe i should put this up here. I also had some info about sprite-limits in the borders. Let's get started.

Screen limits
-------------
Vertically:
First visible line: 8 (d012 = 8)
Last visible line: 12b (d012 = 2b)
That makes 292 visible lines totally.

Transfered to sprite positions we get..
spt-pos 12a: one line visible in lower border.
spt-pos 12b: one line visible in upper border.

Horizontally:
Left border: 48 visible pixels (6 chars).
Right border: 36 visible pixels (4.5 chars).
That makes 404 pixels, right.

Sprite bugs in left border:
All sprites invisible at positions 1f8-1ff.
spt7 invisible at pos <= 1ce.
spt8 invisivle at pos <= 1ee.

Sprite bugs in right border:
spt1 stretch bug at pos >= 14b.
spt2 stretch bug at pos >= 15b.
Bug above first line at pos => 163: spt 3,4,5.
Bug on last line at pos => 164: spt 3,4,5.

Ok. I think that's all. Does anyone have other specs? Please don't post if you have a lowsy TV-set, they always sukk. Did i get those sprite-bugs correctly? Sounds totally wierd :). And finally: DON'T RELEASE before you checked your demo against this spec >:E.

... 110 posts hidden. Click here to view all posts....

2009-02-23 18:03

Ninja

Registered: Jan 2002
Posts: 407

DK: Geez, you are referring to a 4 years old statement that Oswald relativated since then? Besides, there is no per se, as you mentioned. There are parts which do not look better if you extend them in x a bit for the price of cutting them more than half in y, despite all technical complexity. If you manage to have them in the borders without drawbacks, that's way cool, of course.

2020-02-26 13:13

Rastah Bar

Registered: Oct 2012
Posts: 336

Quoting HCL

Sprite bugs in left border:
All sprites invisible at positions 1f8-1ff.

I just realized that this is probably because 63 cycles*8 pixels/cycle = $1f8 pixels. If this is true then it won't happen on NTSC. Does anybody know what sprite bugs there are on NTSC?

2020-02-26 15:01

Krill

Registered: Apr 2002
Posts: 2855

On 65-cycle NTSC machines you have a sprite gap instead.

65 * 8 = $0208, so there is a range of 8 pixels in which you cannot place sprites.

(Of course, you can still reach into and cover the gap with sprites, the gap just applies to their leftmost 8 pixels.)