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Video Driver: NTSC Amigas show blinking artifacts/pixel noise on the screen #14

@dplanitzer

Description

@dplanitzer

Describe the bug
NTSC machines show what looks like pixel noise or artifact bands on the screen. They blink and appear for a fraction of a second at a time. They move seemingly randomly around They are at most 32 pixels wide and their height may be anywhere from a few pixels to a few hundred pixels.

Also note that the cursor in the shell blinks way too fast and it shows a single white line at the bottom edge that shouldn't be there.

To Reproduce
Steps to reproduce the behavior:

  1. Boot the system on an NTSC Amiga
  2. Just observe the screen. You should see artifacts and the shell cursor should blink in a weird way

Expected behavior
No artifacts and cursor blink frequency is the same as on PAL Amigas.

OS (please complete the following information):

  • Version 0.7.0-alpha

Additional context
It looks like as if the Copper program is setting up the sprite registers too late. E.g. the sprite DMA has already started and fetched the control words before the Copper program was able to properly initialize the sprite DMA pointer.

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