Re: [stella] mobile 48 bit sprite kernel

Subject: Re: [stella] mobile 48 bit sprite kernel
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Mon, 6 Jan 2003 13:55:08 +0100
> But I still have the question of why the sprite goes strange near the left
> side of the screen.  I guess since Z26 (and Cyberstella too) reproduce it
> can look at the trace and try and figure out what is happening.

This is because your access to RESP0 happens one cycle too early.
If you access RESPx during the HBLANK, the sprites will be positioned
as if the access had happened right after HBLANK. The first on-screen
cycle is 22 (which is two pixels before the actual display start).
In your demo RESP0 gets hit at cycle 21 when the sprites are near the
left border, but Player0 will be positioned as if REPSP was hit at
cycle 22.

Ciao, Eckhard Stolberg

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