Re: [stella] 11 Invaders "Reloaded"

Subject: Re: [stella] 11 Invaders "Reloaded"
From: Erik Mooney <erik@xxxxxxxxxx>
Date: Fri, 28 Nov 2003 11:15:13 -0500
BTW, sorry for the long lines in that last mail, trying a new mail
client that *told* me it was going to automatically wrap, but didn't...

On Fri, 28 Nov 2003 09:59:38 +0100, Thomas Jentzsch <tjentzsch@xxxxxx> wrote:

Here's how I did the positioning.  First, my code actually displays *15*
columns of invaders, spanning the entire screen.

Correction here: 15*9 - 3 = 132. ;-)

Actually, it's 15*9 + 6 = 141. The 15 columns are always there and can be shifted by up to 6 pixels. OK, it's not *quite* the entire screen, but it's closer than Instigators. Looking at the source, I think my leftmost limit was pixel 20, and then having 15 columns places the rightmost limit very neatly right at 160.

But IIRC there is a big problem with hitting RESPx every 3 cycles, because
gaps in the formation cause the preceding (following) invader to be shifted
by one pixel. And AFAIK nobody has found a solution for that problem yet.
Did you? That would offer some great new options for better code!

No, I never solved that. My solution was just to accept the single-pixel shifting, because I thought it preferable to have the overall tighter formation and easy single-pixel positioning. (You disagreed; I think back when I first posted my demo, you bragged how your beefy invaders would eat my tiny ones for breakfast. ;) )

This would normally cause HMOVE blanks at the left and then hide my first
two invaders. Therefore I am using early HMOVEs, which don't create those

Very clever, of course. I actually wrote my demo some time before we figured out any of the illegal-HMOVE trickery. This would've been around summer 1997, IIRC. ---------------------------------------------------------------------------------------------- Archives (includes files) at Unsub & more at

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