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From: zabot@pompeo.dec.com (Adv.Tech.Mgr-ACT Torino)
Newsgroups: comp.sys.amiga
Subject: PAL and flickering (NTSC programs on PAL Monitor)
Message-ID: <7482@decwrl.DEC.COM>
Date: Mon, 12-Jan-87 04:40:51 EST
Article-I.D.: decwrl.7482
Posted: Mon Jan 12 04:40:51 1987
Date-Received: Mon, 12-Jan-87 18:48:09 EST
Sender: daemon@decwrl.DEC.COM
Organization: Digital Equipment Corporation
Lines: 39

Randy (Spencer) writes:
 
|  PPS, what does an NTSC Amiga program look like on the PAL monitor?  Does it
|  only display in the bottom 200 lines of the monitor when opening a screen?
|  Do they have the spaces between the lines when not in interlace mode, Do they
|  have an interlace mode?  No, they wouldn't.  So they just duplicate every 
|  line twice when in (fake non interlace mode)  But boy they must have flicker
|  *all* the time!
First: relax ! We do NOT have flickering all the time, so if you plan to 
relocate to europe you can still enjoy an AMIGA !!
NTSC-PAL problem. 
  Professional. Most professional terminals and PC (DEC-IBM-..) are using some 
sort of NTSC standard also in Europe. Home computer (ALL of them) are using 
PAL standard. So even a C64 has the same problem. The result is very simple.
  The apparence is that we have a smaller usable area on the video screen and a 
different ratio ( vert size vs oriz. size). This means that a CIRCLE in NTSC 
is an oval in PAL.This is due to the higher number of lines (625) on the same
phisical space ( screen size) compared to the NTSC (525 ??). 
  The differnt ratio creates a lot of problem with many traditional computer 
and programs ( think of a CAD program :-) drawing a circle !!). This is not 
the case with many programs on the Amiga 'cause they use the intuition 
interface, so you can resize the window and the ratio as well.
  One think that is difficult to understand is the relation of the 200/400 
lines with the 525 in NTSC. I never counted the border lines, are they 125 ? 
  Let's now consider Amiga. 1.1 is the same old story. ( smaller screen area).
With 1.2 PAL has an extra area usable, for a total of 256 lines ( or 512 in
interlace mode). That's a figure I like more ( a power of two has always the
right to appear in a computer ! :-). And we can really use that area which is
visible via Intuition. This means ,most of the time, that you can drag any
window in this area, but very seldom we can enlarge your window to include 
this bottom area. This depend only on the way your program was written.
To make a long story short. A good sighted guy can have as many as 51 lines
on his terminal emulator. Or better , anyone can have a regular 25 lines 
terminal emulator PLUS an extra window ( 6-7 lines long ).
  Flickering. In Europe the monitors are totally different from the US ones. I
think C= is using Philips monitors. The final result is that, even if these
monitors seam to be a better quality that the NTSC ones, we have the same
level of flickering under the same conditions.
  marco