V9990 and VGA tradeoffs

Paragon (1232)

21-02-2023, 18:19

Would you be comfortable having VGA output, but missing interlaced and 424-line modes, and PAL 50 Hz mode? In other words - having progressive scan @ 60 Hz only?

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By Grauw

Ascended (10821)

21-02-2023, 19:03

Can you elaborate a bit more? Are you perhaps thinking of adding an integrated scandoubler, one which only supports 240p @60Hz?

By Eugeny_Brychkov

Paragon (1232)

21-02-2023, 19:32

Something like this. If I figured out properly 424 lines are achieved by halving vertical frequency (30 Hz for NTSC and 25 Hz for PAL, not talking about B5 and B6). There're actually several gray areas of the chip operation I am not sure about, therefore can only talk about what can be definitely implemented.