Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!clyde.concordia.ca!nstn.ns.ca!news.cs.indiana.edu!sdd.hp.com!cs.utexas.edu!evax!cs4344af From: cs4344af@evax.arl.utexas.edu (Fuzzy Fox) Newsgroups: comp.sys.cbm Subject: Re: C128 Housekeeping Message-ID: <1991Feb6.012940.14931@evax.arl.utexas.edu> Date: 6 Feb 91 01:29:40 GMT References: <1991Feb4.155054.27418@cs.dal.ca> <1991Feb5.002513.26331@evax.arl.utexas.edu> <1991Feb6.001325.3292@spool.cs.wisc.edu> Organization: Computer Science Engineering Univ. of Texas at Arlington Lines: 21 In article <1991Feb6.001325.3292@spool.cs.wisc.edu> kolstad@jomby.cs.wisc.edu (Joel Kolstad) writes: > >Now wait a second here. I've always been under the impression that to >interlace something, you have to use DIFFERENT SCAN LINES for every other >frame. > Yes, that is true. But think about it: NTSC video uses interlacing all the time. I forget the number of scan lines, but the number of scan lines generated by the VIC chip is 1/2 of the NTSC standard. Every 1/60 second the chip generates the same video information, but shifted down slightly, as the standard dictates. The 'scan lines' that you see are actually two scan lines. When interlacing, the chip is continually told differing views of what the screen looks like, so on the second pass, it draws different values on the odd scanlines than it did on the even lines. -- begin 644 .signature H5&AI