Re: [stella] Some Questions That Bug Me

Subject: Re: [stella] Some Questions That Bug Me
From: Glenn Saunders <cybpunks@xxxxxxxxxxxx>
Date: Thu, 21 Jun 2001 22:40:16 -0700
At 04:16 PM 6/21/2001 -0700, you wrote:
First, I just read the discussion about the maximum
displayed lines on a TV screen.  What are the maximum
lines period?  Is that number hard, or can that be
expanded a bit like the visible screen can?

If you count interlace, 525 is the maximum number of scanlines in NTSC. Many of these are either not visible and/or used for special purposes like blanking and sync.

I would say that the maximum usable number of scanlines is 482, i.e. 241 noninterlaced, again, with much of the picture going into overscan.

Second, how does Activision get that border?  It seems
like the Atari games they make have a black border
around the screen.  There's no sign of those weird
lines like in the black and white mode of Space
Invaders.  Do they just leave the color register for
black, cycle count in, and start at the playfield?
(This seems like it would take up valuable processing
time, so I'm not sure of my theory.)

They often used a wide-mode ball and set it to the side, or did an HMOVE on every scanline.

I don't really like that they did this, however, as it wastes potentially valuable screen resolution, constraining the action, as well as potentially wasting a sprite and/or cycles in the kernel. I'd rather have sprites fight with the comb area than to block it off entirely. You've only got 160 pixels of accuracy to play with.

Activision games, however, by and large, don't seem to suffer for it. They were great at making painless compromises.

Glenn Saunders - Producer - Cyberpunks Entertainment Personal homepage: Cyberpunks Entertainment:

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