Subject: Re: Ntsc/Pal switching
From: "Garfield Benjamin" <[email-masked]>
To: "AMOS MAILING LIST" <[email-masked]>, "Matt Ward" <[email-masked]>
Date: Mon, 3 Nov 1997 15:05:46 -0500

> I have a Pal machine so am used to all the various to dos with that.
> I can also force the computer to use an NTSC screen by using a
> specific Doke. (Similar I suppose to Set Ntsc in AMCAF). What I'm
> wondering is this:
> 1) How close to a real NTSC machine is this?
> ie if my game fits on my pretend NTSC machine will it be okay on a
> real one?

   Have little idea as I have never seen a true PAL machine use the
   NTSC-switch.

   I assume it is very close to a true NTSC-mode machine...

> 2) If a real Ntsc machine used Set Ntsc or Set Pal (or my Doke) what
> would happen?

   Depends... If we had booted in PAL then we'd flip back to NTSC-mode.
   If we were already in our native NTSC-mode then our display would
   not change at all.

   As for switching to PAL, it would be the same for us.  If we had booted
   in PAL then no effect from the PAL-switcher, but if we were in our
   native NTSC-mode, we'd be switched to PAL-mode.

   When I switch to Pal, using Poke $DFF1DC, 32, my display shifts up
   around 30 pixels, leaving a large blank area in the lower part of the
   display.

   Apparently, the display is actually "compressed" and perhaps the
   starting line is shifted up a bit as well to allow a PAL-screen to fit
   within the display.

   If any of you PAL-users have played an NTSC-only game then I
   assume you know what I'm talking about.  The screen is way up to
   the top of the monitor and there is a large blank area at the bottom.

   Hope this helps...

      Take  care,   
      GARFIELD
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