Re: [hatari-devel] video freq set to 60 Hz instead of 50 Hz for Falcon VGA

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 06/03/2024 à 14:29, Nicolas Pomarède a écrit :

> Hi
>
> I didn't try screenpain yet ; when generating asm source for vga 32 Mhz, 
> can you compare it to vga 25 Mhz to see what is changing ?
>
> I had the feeling that register-wise only bit 2 in ff82c0 was involved 
> in RGB/VGA, by setting clock to 25 or 32 MHz.
>
> I don't see which setting allows vga with a "non vga" clock.

nevermind, I tried it myself :

--- VGA32.S     2024-03-06 14:38:26.928919655 +0100
+++ VGA25.S     2024-03-06 14:41:35.710411188 +0100
@@ -8,14 +8,14 @@
 * Monitor: RGB/TV
 * 640*400, 16 Farben, 50.0 Hz (interl.), 15625 Hz

-        MOVE.L   #$1FE0199,$FFFF8282.W
-        MOVE.L   #$50004D,$FFFF8286.W
-        MOVE.L   #$FE01B3,$FFFF828A.W
+        MOVE.L   #$1900141,$FFFF8282.W
+        MOVE.L   #$3E004D,$FFFF8286.W
+        MOVE.L   #$16C0156,$FFFF828A.W
         MOVE.L   #$2700265,$FFFF82A2.W
         MOVE.L   #$2F007E,$FFFF82A6.W
         MOVE.L   #$20E026B,$FFFF82AA.W
         MOVE.W   #$200,$FFFF820A.W
-        MOVE.W   #$182,$FFFF82C0.W
+        MOVE.W   #$186,$FFFF82C0.W
         CLR.W    $FFFF8266.W
         MOVE.W   #$0,$FFFF8266.W
         MOVE.W   #$6,$FFFF82C2.W

So, clock bit is changed in ff82c0 (which is what Hatari is using at the 
moment), but it also changes the 6 registers at ff8282 - ff828c that 
define the duration for horizontal lines.

This is sthg that is not supported at the moment, this will require much 
more code (and a better understanding of all these regs for myself :) )

Nicolas