Corrupt native video in NTSC

[hth313]

Running on NTSC machines often makes AROS end up with a corrupt screen like this:

In FS-UAE, set up an A3000, tick the NTSC checkbox, install AROS ROMs and boot from a standard Commodore 3.1 floppy image, like the Installer or Workbench. The above screenshot is from such setup.

It can also be reproduced on hardware using an A3000, which has a jumper for PAL/NTSC. With the jumper set to NTSC, a similar screen effect is often seen. If changed to PAL, it works as expected (no strange video).