lphillips@lpami.wimsey.bc.ca (Larry Phillips) (09/21/89)
In <5238@merlin.usc.edu>, aliu@castor.usc.edu (Terminal Entry) writes: >What is the cause for the color flicker experienced with various amiga terminal >programs such as JrComm, etc, when using ANSI color mode? Can it be fixed? >It seems to me that the text gets scrolled a fraction of a second before its >color gets scrolled. The colour does not 'get scrolled' at all. the text you see on te screen (any screen, any window), is the actual bitmap, ie. it is not scanned out from a character generator each time the screen paints, as is the case with many machines. Each colour you see on the screen is a direct result of which bits in the bitplanes are on and which are off. The problem is that there is just not enough time to scroll all the bitplanes during one vertical interval, so some bitplanes are scrolled, and some are not when the raster comes by. >I have experienced this problem at speeds of 2400, which should be more >than slow-enough for the amy to handle. Yet, I haven't found a term that >gives rock-solid 16-color ansi emulation yet. Is there such a thing? It has nothing to do with the speed of the received data. >(I always thought that is the c64/128 could do flawless 16-color scrolling, >the amiga should have no problem with it. Yet I find myself always in need >to adjust the color pallete on my terminal, or not use color at all..) Well, the 64/128 do it completely differently. They use a text buffer (contents in ASCII, and a colour table the same size as the text buffer (size is equal to the number of characters that can display on the screen), and there is not nearly as much data to scroll as there is on the Amiga display. If you feel strongly about it, let Jack know, and perhaps he'll put in an option for allowing double buffering of the display. It will eat a lot of ram, and may have other problems though. -larry -- The Mac? Oh, that's just like a computer, only slower. +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+
aliu@castor.usc.edu (Terminal Entry) (09/21/89)
I am posting this in the name of a couple of other users, so please reply by a public post. Thank you. Question: What is the cause for the color flicker experienced with various amiga terminal programs such as JrComm, etc, when using ANSI color mode? Can it be fixed? It seems to me that the text gets scrolled a fraction of a second before its color gets scrolled. I have experienced this problem at speeds of 2400, which should be more than slow-enough for the amy to handle. Yet, I haven't found a term that gives rock-solid 16-color ansi emulation yet. Is there such a thing? (I always thought that is the c64/128 could do flawless 16-color scrolling, the amiga should have no problem with it. Yet I find myself always in need to adjust the color pallete on my terminal, or not use color at all..) Thanx in advance.
consp11@bingvaxu.cc.binghamton.edu (Optimist Prime) (09/21/89)
In article <5238@merlin.usc.edu> aliu@castor.usc.edu (Terminal Entry) writes: >[...] >Question: > >What is the cause for the color flicker experienced with various amiga [...] >programs such as JrComm, etc, when using ANSI color mode? Can it be fixed? >It seems to me that the text gets scrolled a fraction of a second before its >color gets scrolled. > >I have experienced this problem at speeds of 2400, which should be more >than slow-enough for the amy to handle. Yet, I haven't found a term that >gives rock-solid 16-color ansi emulation yet. Is there such a thing? >[...] I have the same problem at 1200 baud, which is even stranger. And it becomes even more pronounced when using interlaced screens with 16 colors (such as JrComm). I'm not a techie, but I'm almost positive that the reason behind it has to do with the number of bit planes used to draw the screen. With 16 colors, the Amiga has to scroll 4 bit planes together, all at the exact same instant. As wonderful as the Amiga is (I wouldn't trade for ANYTHING! :-) ), there is a limit to what can be done. As for the part about the 64/128's scrolling, don't forget that the 64/128 were dealing with an 80x25 character display; it's much easier to scroll 2,000 characters than it is to scroll a 640x200 (or 640x400) bitmapped display. --Brett Kessler
cmcmanis%pepper@Sun.COM (Chuck McManis) (09/22/89)
In article <5238@merlin.usc.edu> aliu@castor.usc.edu (Terminal Entry) writes: >What is the cause for the color flicker experienced with various amiga terminal >programs such as JrComm, etc, when using ANSI color mode? Can it be fixed? >It seems to me that the text gets scrolled a fraction of a second before its >color gets scrolled. The Amiga is a bitplane oriented machine. When it "scrolls" the screen it is actually scrolling some number of bitplanes depending on the depth of the screen. When one calls ScrollRaster() it begins the scroll by setting up four blits to move the data, and then executes them one after another. If they aren't all done by the time the screen is being displayed again you will see different colors. What determines how long it take? Well a combination of things, some involving what the CPU is doing (it has to set up the blitter) and some involve what Agnus/Denise are doing (fetching data from CHIP ram for the display) and of course if any other task is making demands on the blitter (reading floppies, moving bits etc). Generally, the more bitplanes (and hence more colors) you use the more contention you will get from Agnus/Denise, and the more tasks you are running the more likely you are to hit contention on the blitter or CPU. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you. "If I were driving a Macintosh, I'd have to stop before I could turn the wheel."
bdb@becker.UUCP (Bruce Becker) (09/22/89)
In article <2452@bingvaxu.cc.binghamton.edu> consp11@bingvaxu.cc.binghamton.edu.cc.binghamton.edu (Optimist Prime) writes: |In article <5238@merlin.usc.edu> aliu@castor.usc.edu (Terminal Entry) writes: |>[...] |>Question: |> |>What is the cause for the color flicker experienced with various amiga [...] |>programs such as JrComm, etc, when using ANSI color mode? Can it be fixed? |>It seems to me that the text gets scrolled a fraction of a second before its |>color gets scrolled. |> |>I have experienced this problem at speeds of 2400, which should be more |>than slow-enough for the amy to handle. Yet, I haven't found a term that |>gives rock-solid 16-color ansi emulation yet. Is there such a thing? |>[...] | |I have the same problem at 1200 baud, which is even stranger. And it becomes |even more pronounced when using interlaced screens with 16 colors (such as |JrComm). I'm not a techie, but I'm almost positive that the reason behind it |has to do with the number of bit planes used to draw the screen. I don't know if it's the same phenomenon, but my A1000 started doing this a while back when drawing some kinds of hi-speed image changes. It seemed to start after I used a genlock and (ugh) plugged it in while it was powered on. I think I might have fried some IC inside, so it might or might not be the same thing. Cheers, -- __ Bruce Becker Toronto, Ont. w \cc/ Internet: bdb@becker.UUCP, bruce@gpu.utcs.toronto.edu `/,/-e BitNet: BECKER@HUMBER.BITNET _/ >_ Why would I dog you out? - G. Clinton