Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!rutgers!cbmvax!hood
From: hood@cbmvax.commodore.com (Scott Hood)
Newsgroups: comp.sys.amiga
Subject: Re: PAL: no. of lines?
Message-ID: <15621@cbmvax.commodore.com>
Date: 5 Nov 90 23:29:49 GMT
References: <1470@skye.cs.ed.ac.uk>
Reply-To: hood@cbmvax.commodore.com (Scott Hood)
Organization: Commodore, West Chester, PA
Lines: 26

In article <1470@skye.cs.ed.ac.uk> db@lfcs.ed.ac.uk (Dave Berry) writes:
>I recall someone saying that PAL amigas output 512 line screens.
>Is this right?  PAL TVs have 625 lines, so I would have expected
>that number from a PAL Amiga (with 312 lines in non-interlaced modes).
>
>--
> Dave Berry, LFCS, Edinburgh Uni.      db%lfcs.ed.ac.uk@nsfnet-relay.ac.uk
>
> "Dumping 33546240 bytes to dev 0x70e0100, offset 124968.
> Don't cycle power ..."

PAL video modes are made up of two 312.5 line fields being scanned out
at 50Hz each to make up a frame of 625 lines at 25Hz rate using
interlacing.  The default PAL Amiga screen is 512 lines long but of
coarse more is available via overscanning.  About the most number of
lines in a PAL Amiga would be about 576 lines more or less due to the
trade offs you are willing to have in regard to vertical blanking.  NTSC
is much the same situation but with different numbers.

Scott Hood

-- 
--
Scott Hood, Hardware Design Engineer (A3000 Crew),  Commodore-Amiga, Inc.
   {uunet|pyramid|rutgers}!cbmvax!hood   hood@cbmvax.cbm.commodore.com
  "The views expressed here are not necessarily those of my employer!"