Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!unmvax!ncar!ames!amdcad!sun!pitstop!sundc!seismo!uunet!mcvax!unido!rmi!kkaempf
From: kkaempf@rmi.UUCP (Klaus Kaempf)
Newsgroups: comp.sys.amiga
Subject: Re: Bug in decision for PAL or NTSC
Message-ID: <1329@rmi.UUCP>
Date: 7 Dec 88 14:56:01 GMT
References: <1994@van-bc.UUCP>
Reply-To: kkaempf@rmi.UUCP (Klaus Kaempf)
Organization: RMI Net, Aachen, W.Germany
Lines: 29

In article <1994@van-bc.UUCP> lphillips@lpami.van-bc.UUCP (Larry Phillips) writes:
: 
: > But what is the 'line frequency' pin from the power supply good for ??
: > Doesn't the Amiga check that line to decide if it should display PAL (50Hz)
: > or NTSC (60Hz) ?
: 
: I hope not. This would prevent PAL Amigas from being used in North America,
: and NTSC Amigas from being used in Europe.
: Europeans is that some (many?) programs developed in North America don't
: look right on PAL systems, but at least a few vendors have PAL Amigas to
: test with, and it has to help the situation a bit.
: 
: -larry
To clarify: PAL == 256 lines/frame, NTSC == 200 lines/frame.

PAL -> 50 Hz -> 25 frames/sec -> 6400 lines/sec
NTSC -> 60 Hz -> 30 frames/sec -> 6000 lines/sec

So both need about the same dma bandwith to display a standard picture. You
can't display 256 lines with NTSC, can you ??

By looking at the line frequency at boot-time, the amiga should decide
whether to display 200 lines (60 Hz, no dma-time for 256 lines) or
256 lines (50 Hz, no 200 lines please !).


Still puzzled,

Klaus