db@cs.ed.ac.uk (Dave Berry) (11/05/90)
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 ..."
hood@cbmvax.commodore.com (Scott Hood) (11/06/90)
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!"
spence@cbmvax.commodore.com (Spencer Shanson) (11/06/90)
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). The PAL Amiga generates 256 lines as default in non-interlaced mode, and 512 in interlaced mode. The other 113 lines form the display border (in the background colour of the vertically highest screen). The height of the display can be changed using overscan modes (which under 2.0 can be set from a preferences file). Howzat? > >-- > 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 ..." -- --------------------------------------------------------------------------- Spencer Shanson - Amiga Software Engineer | email: spence@commodore.COM | or uunet!cbmvax!spence All opinions expressed are my own, and do not | "A picture is worth 1000 (necessarily) represent those of Commodore. | words, or about 300,000 | bytes."
rda233b@monu6.cc.monash.edu.au (m.l. 8933859 leighton) (11/06/90)
db@cs.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). A standard, non-interlaced, non-overscan PAL screen is 256 lines long. Overscan increases this to 312, and interlace doubles everything. (Meaning that the _are_ 624 lines to an overscan, interlaced screen.) Please feel free to correct me... > Dave Berry, LFCS, Edinburgh Uni. db%lfcs.ed.ac.uk@nsfnet-relay.ac.uk -- /// ^^^^^ __ /// (o o) Didn't 25 years of Doctor \\\/// Simon Cocking, ^ Who teach you not to trust \XX/ rda233b@monu6.cc.monash.edu.au `-' names like Intel & Zilog?
peterk@cbmger.UUCP (Peter Kittel GERMANY) (11/06/90)
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). Well, you never can use the full screen height. Some of these lines are dedicated for checking purposes, don't know whether also sync is counted with them. So, 625 is the absolute maximum and far more than what is visible. BTW also NTSC has more than the Amiga 400 lines, I think NTSC is about 525 lines (or similar). -- Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk
esucv@warwick.ac.uk (Blitter) (11/06/90)
I remember reading a while back that the PAL tv system uses less than 625 lines for the actual picture (eg teletext uses some of the non-visible 'spare' lines). This could explain why the Amiga only displays 576 lines. -Tony