Quote:
Originally Posted by Toni Wilen
Uses some strange programmed display mode that is sort of PAL compatible but also sets BEAMCON0 bits that no one has set previously ("DUAL" bit which apparently does something strange).
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Some more information. "DUAL" bit actually does nothing. But there is something unexplained because HBSTRT/HBSTOP bits seem to do nothing. I set exact same programmed mode values as this demo on my real A1200. (Indy AGA MK1 -> LCD and 8833II via composite out), left or right border never blanked, not even partially and I tried lots of HBSTRT/HBSTOP values..
Vertical blanking values work as expected. (and they only work if VARVBEN bit is set). Nothing seems to enable horizontal blanking. I tried all BEAMCON0 bits, nothing happened with horizontal blanking.
Horizontal and vertical sync values also work as expected too.
Demo sets quite large value to HBSTOP ($80) and it still shows complete horizontal screen which confirms that HBSTRT/HBSTOP are ignored which can't be right because it would not work very well with programmed display mode monitor drivers or Linux AGA console/X-Window screens..
Something must be missing..