Are scanlines under 262 acceptable?

[yuppicide]

Like the new additions to the Scanline section of your website.. ie: Timing section. Maybe it's not new, but it's new to me since I haven't been there in awhile.

 

Are there any instances of scanlines being UNDER 262 or will bB not allow it? If so, is under 262 acceptable?

 

I have other issues with my game and I noticed when something went off the bottom of the screen in my game scanlines were 261 (using Fast 'On The Fly' Way) and that's why I was originally going to ask this question. Further inspection using the 'Typing Is Fun' Way revealed it went to 261, 263, 268, and back to 262, but I thought I'd still ask the under question anyway.

[RevEng]

The 262 is an ideal. If you have a few less or a few more it will likely work on the majority of TVs without rolling. One note on that - if you have an odd number of scanlines it will cause pal consoles to display the game in B&W, due to the way pal alternates the colorburst phase each line.

 

To answer the bB specific question, bB won't let you do less than 262. It uses a timer to ensure the minimum number of scanlines is 262, even if they're blank.

[SeaGtGruff]

To answer the bB specific question, bB won't let you do less than 262. It uses a timer to ensure the minimum number of scanlines is 262, even if they're blank.

Actually, that's if you're using drawscreen. If you're using a custom kernel, it's possible to draw fewer than 262 lines in batari Basic.

 

Michael

[RevEng]

Very true!

[SeaGtGruff]

Very true!

Something else I thought of... If you change the timer's value in your code, it will mess up the timing for bB's kernel. So if you wanted to display fewer than 262 lines for some reason, you could set the timer to some pre-determined value right after calling drawscreen, thereby tricking bB into displaying only 260 lines, or 258 lines, etc.

 

Nothing in this world is fool-proof, because there's always some fool who'll find a way to mess it up! And like as not, it will be by doing something simple that the designers never expected a rational human being to do.

 

Michael

[yuppicide]

I think your bitmap demo is something then never envisioned the Atari 2600 capable of.

[SeaGtGruff]

I think your bitmap demo is something then never envisioned the Atari 2600 capable of.

My bitmap kernel isn't that special. The idea of combining three copies of player0 and three copies of player1 to get "one big sprite" is nothing new, and the idea of stretching that to six copies of each player by using 30 Hz flicker is also nothing new.

 

Michael

[yuppicide]

I'm just saying I don't think they envisioned it when they originally made the system. I guess a lot of these games they never envisioned either.