lcs@remus.rutgers.edu (Lyle C. Seplowitz) (02/04/91)
I'm rather paranoid about opening up computer hardware (I have a
list of poor electronic things that suffered from my curiosity
...luckily the damage to my disk drive was very minor!). What I would
like to do is clean the inside of my C128 (especially the keyboard).
I've had the computer for over 5 years and never cleaned it once! Can
anyone provide some instructions for doing this (make sure you include
sensitive parts of the computer).
In case you haven't seen it...I recently downloaded a program called
"reticulate" for the 64. It is a demo program
(milton.u.washington.edu: public/download/c64current/demos) that
makes the 64 display in interlace mode! It can work in 640x400,
320x400, and 160x400 (yes both horizontal and vertical interlace). I
have no idea how it is done (the demo is somewhat old, from 1988 I
think). If you do download it, it is very sensitive. Only have one
drive turned on. Also, it seems to only work with a 1541 (or 1571 in
1541 mode). It wouldn't run fully on my 1581. The sample picts are
good but the really nice part of the demo is at the end! I'm still
amazed at how the ending is done.
--
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l c s @ r e m u s . r u t g e r s . e d u
-------------------------------------------------------------------------------digdon@ug.cs.dal.ca (Mike Digdon) (02/04/91)
About Reticulate... sorry to disappoint you, but the whole thing is just an illusion. It really isn't doing interlacing. The pictures as you see them look exactly like what they really are.. Using SS v5, I saw that the pictures have just been crunched, and in actual fact only take up half the screen (ie: 100 pixles) and not the 200 as the program says. Also, the 16 bit character sets aren't interlaced either. Using the character set monitor, you could see the complete character set. The demo is a fraud... in order to give the illusion, the pic at the top is moved up and down a pixel just to make it look interlaced, but that is it... nice trick though.. -- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Mike Digdon: digdon@ug.cs.dal.ca + My 64 can still get the + + mike@ac.dal.ca + job at hand completed!! + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
roger@garfield.cs.mun.ca (Roger White) (02/05/91)
The interlace display is not a hardware effect but a software effect. It is true that the screen is only being moved a pixel at a time, back and forth (using the VIC's horizontal and vertical movement address) thus every second row is on top of the other. It causes the image to blur thus making it look better and give the illusion of interlace. The bitmap has every second pixel row cut out (starting at the top row and/or at the side) for one part and every second pixel (starting at one down from the top row and/or one from the side) for the other. Each bitmap is flashed on the screen during its specified interval (when the screen is moved one pixel the second bitmap is flashed, when the screen is normal the other bitmap is flashed) giving it the jitters and the illusion of an interlace screen. You are actually seeing a 640x400 display, but it is just two bitmaps flashed on top of the other. It does give a nice effect though, if only the jittering could be calmed down a little. The reason why Snapshot only shows a half bitmap is because when you press the button it only freezes one of the screens and you get a half bitmap. You could end up with the second half if you freeze it later on. (by half bitmap I mean every second pixel removed) This may not be the way it is done, but is the only way I can see it working for a C64. As mentioned they may only be using one screen and moving it to make it look like interlace thus only really showing a 320x100/160x200/160x100 screen and lying about the resolution. I have only seen the demo, I haven't looked into the code. R.White -- Boot it up? I did A LOT of that!| Roger White (Sam-Cheers) | Memorial University of Newfoundland --------------------------------| St. John's, Newfoundland, Canada ..uunet!odie.cs.mun.ca!roger, roger@odie.mun.edu, roger@odie.cs.mun.ca
cs4344af@evax.arl.utexas.edu (Fuzzy Fox) (02/05/91)
In article <1991Feb4.155054.27418@cs.dal.ca> digdon@ug.cs.dal.ca (Mike Digdon) writes: >About Reticulate... sorry to disappoint you, but the whole thing is just an >illusion. It really isn't doing interlacing. Yes, it is an illusion, but when you get down to it, that's what interlacing really IS, an illusion. When you interlace a picture, you draw half of the picture during 1/60 of a second, then the other half for the other 1/60 of a second. If you freeze the image with SS v5, what you are looking at is only half the picture. You will notice if you do it several times that the two images are slightly different from one another. Try it and see. The "net effect" when you alternate the two pictures ever 1/60 of a second is that it "looks" like there is more resolution. This is interlacing. -- begin 644 .signature H5&AI<R!S<&%C92!U;FEN=&5N=&EO;F%L;'D@;&5F="!B;&%N:RX-"L1S ` end
kolstad@jomby.cs.wisc.edu (Joel Kolstad) (02/06/91)
In article <1991Feb5.002513.26331@evax.arl.utexas.edu> cs4344af@evax.arl.utexas.edu (Fuzzy Fox) writes: >In article <1991Feb4.155054.27418@cs.dal.ca> digdon@ug.cs.dal.ca (Mike Digdon) writes: >>About Reticulate... sorry to disappoint you, but the whole thing is just an >>illusion. It really isn't doing interlacing. > >Yes, it is an illusion, but when you get down to it, that's what >interlacing really IS, an illusion. > >When you interlace a picture, you draw half of the picture during 1/60 >of a second, then the other half for the other 1/60 of a second. If you >freeze the image with SS v5, what you are looking at is only half the >picture. You will notice if you do it several times that the two images >are slightly different from one another. Try it and see. > >The "net effect" when you alternate the two pictures ever 1/60 of a >second is that it "looks" like there is more resolution. This is >interlacing. > 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. I can certainly tell you that on my Amiga in 640x200 mode, there is a certain (black) gap inbetween each scan line on the monitor. In interlace mode, these black lines get filled in with more video. The C-64, on the other hand, is using the EXACT SAME scan lines on every other frame. (And unless one of you out there knows something I don't about the VIC chip, you can only scroll the screen in 1 pixel incremements...) I haven't seen the demo, so I don't know if it looks any better than standard 640x200 -- but I still don't think that the mothod it's using can be called true interlacing. Just my $.02... ---Joel Kolstad kolstad@cs.wisc.edu
cs4344af@evax.arl.utexas.edu (Fuzzy Fox) (02/06/91)
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<R!S<&%C92!U;FEN=&5N=&EO;F%L;'D@;&5F="!B;&%N:RX-"L1S ` end