STraTOS 1997 April & May/STraTOS 1 - 1997 April & May.iso/CD01/INTERNET/SITES/RAND/ALL96.LZH/t0222/text0032.txt

Text File | 1996-03-07 | 1.7 KB | 36 lines

> > > Why is there no acceleration possible on RGB ?
> >
> > The Videl is clocked by system clock (32 MHz) when it generates TV screen.
> > If I change the system clock to e.g. 40 MHz, there is no more TV compatible
> > output from Videl...
>
> That's crap! Can't you change the Videl speed to 32MHz? On the Screenblaster
> you can change it, or can't you?

In fact, the Videl can use 2 different clocks: one which frequency is 32 MHz,
and another of 25 MHz. Speed-enhancing cards changes the 32 MHz clock to 40 or
50 MHz, and the 32 Mhz frequency cannot be used anymore.
As the 32 MHz frequency is the default one on RGB modes, they can't work
properly. But it's quite easy to generate 320*200 True Color modes with a Videl
frequency of 25 MHz ! This frequency isn't changed by any cards I know, for
the reason that the default VGA modes are in 25 MHz mode, thus they can
still work when the system clock is 40 or 50 MHz...
The program Videl Inside generates such videos modes. It features a 320 pixels
wide RGB mode in True Color with a clock of 25 MHz. I don't remember if the
height of this mode is 200 lines, but it should work anyway, even with
accelerated Falcons! It replaces the default video mode, so if Bad Mood uses
the Setscreen Xbios call, it should work well.
VI can be found at the following URL:
ftp://ftp.cnam.fr/pub/Atari/Falcon/Graphics/vi_1_2.zip

> Have anyone tetsted BM on a RGB/TV yet? Any difference in speed?

As I own a multisynchro monitor, so I was able to test BM on both VGA and RGB
modes. For the same WAD file (DOOM2.WAD), and the same map (map01), The RGB
mode makes BM a little faster than under VGA mode.
In RGB I get 4.3 fps and in VGA 4.0 fps for the same view.

Zerkman / Trisomic Development