Re: BIOS Video and DirectX for Apple II Emulator

[steve@dosius.zzn.com (Dosius)]

"Bryan Parkoff" <BParkoff@satx.rr.com> wrote in message news:<5iidnSNQWNFe1dWjXTWQlg@giganews.com>...
> You may be surprised that exact color does not look the same.  For
> example, BIOS Video shows 16 out of 256 colors on 320x200 resolution that it
> only uses 13h on INT 10h.  DirectX 7-9 shows 16 out of 16,777,216 colors on
> either 320x200 resolution and 640x480 resolution.  Blue color is little
> bright in BIOS Video than DirectX.  Please explain why.

BIOS video in mode $13 offers 256 out of 262,144 (256*1024, or 64^3)
colors.  See Dapple 1.25 for an example.

>     Try to compare XGS-DOS and XGS-Win32.  You will notice that the colors
> are not the same.  XGS-DOS is the exact same as real Apple IIgs.  The
> problem is that XGS-Win32 makes exact color little darker.  You use 16-bit
> color that will show little dark blue color, but you use 24-bit color that
> will show darker blue color than 16-bit color.  You can notice why it is the
> difference between 16-bit and 24-bit colors.
>     Do you have idea how to improve color-looking that should match the SAME
> color between 16-bit and 24-bit?  Or..should we change RGB function to
> match?  I always complain about the color problem, but XGS-DOS is much
> better.  Is it true that 16,777,216 is the maximum for colors?  I have heard
> that it may be billion color than 16.7 million color.

No, there is a 32-bit color mode. (16,777,216 - 256^3 - 24 bits)

>     Is there a way that we can program Apple II Emulator to match real Apple
> IIgs color?  Or...should we add RGB scale/scroll in this emulator that it
> allows the users to modify RGB scale/scroll that will cause the color to
> change.  Please adsvise....

Aiming for DOS?

Take a look at Dapple 1.25, which uses 24-bit color values mapped down
to 18 bits in 8-bit mode.  Although it has been supplanted by Dapple
][ - both should emulate IIgs color quite well.  It can be done. ;)

-uso.