burton@mitisft.Convergent.COM (Philip Burton) (09/27/90)
At a local computer store, I just got a demo of Windows 3 running on a NEC 3D (interlaced only) running at 1024 x 768 x 256 colors. Or so the salesman claimed. It looked beautiful. Of course, I'd have to buy a certain VGA card to get that performance. The lighting in the general area was incandescent, rather than fluorescent. The salesman claimed that was an important difference. My question to the net: Why do you (not) run 1024 x 768 interlaced on a NEC 3D or similar monitor? Lighting? By the way, the VGA card was an Orchid Prodesigner II, which can take up to 1 MB of video RAM. It's $300 for 512 KB, almost $100 more than an ATI card. --Phil Burton--
pnl@hpfinote.HP.COM (Peter Lim) (09/29/90)
> The lighting in the general area was incandescent, rather than fluorescent. > The salesman claimed that was an important difference. > Yes it makes a difference. Fluorescent light is not exactly continuous; sort of pulsating --- much the same as your computer terminal. And the usual effect is that fluorescent kind of amplify the flickering effect of your monitor. I probably should know the theorectical reason for this; I'm an electronic engineer :-), but fact is I don't ! > My question to the net: Why do you (not) run 1024 x 768 interlaced on a > NEC 3D or similar monitor? Lighting? > With 256 colors, 1024 x 768 interlaced looks a lot better than with 16 colors. The difference is dithering. Under MS Windows, with 16 colors, dithering is done to simulate the missing colors. Dithering means that you kind of have dots of black interpersed over a white background to simulate grey. Interlace is not good at aligning neighbouring lines with patterns very well. They usually end up slightly different on each pass. Hence, you see flicker. I know I'm not explaining this too well, but that's the general idea. Other than 16 vs. 256 color, the other reason I can think of not to run 1024 x 768 on NEC 3D is physical size. At 800 x 600, I find characters on a 14 inch monitor just a little small. It is a lot smaller on 1024 x 768. Of course you can use 8514 fonts; but that means that you will end up not gaining any desk space at all (in fact you lose some compared to 800 x 600 with VGA fonts). > By the way, the VGA card was an Orchid Prodesigner II, which can take up > to 1 MB of video RAM. It's $300 for 512 KB, almost $100 more than an ATI card. > If you must have 1024 x 768 x 256 colors, you can probably buy some Taiwanese clone VGA cards (usually using either the Tseng Lab 4000 or Trident 8900 (??) chip sets) at about half the price. However, if your idea is to run Windows programs, then, you are likely to find the display incredibly (sp ?) slow ! Personally, I would wait for those 34010 cards' price to come down. Things like Hercules Graphics Station card (best price I've seen so far is about $600). They will make Windows run much faster (like 3 to 10 times faster than the fastest dumb VGA card ?). Currently I'm using a 386 25 MHz no cache with ATI VGA Wonder at 800 x 600 x 16 colors resolution. Looks pretty good. Regards, ## Life is fast enough as it is ........ Peter Lim. ## .... DON'T PUSH IT !! >>>-------, ########################################### : E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, : Tel: (065)-279-2289 (ICDS, ICS) | Telnet: 520-2289 1150 Depot Road, __\@/__ ... also at: pnl@hpfipnl.HP.COM Singapore 0410. SPLAT ! #include <standard_disclaimer.hpp>
e4666881@rick.cs.ubc.ca (richard louie) (09/29/90)
The NEC 3D should not be ran too long in 1024 x 768 mode
because of the feature referred to as interlaced. When a display
is interlaced, you will tend to see a flicker on the screen. This
flicker is caused by the monitor needing to refresh the display
to get the 1024 x 768 more often than when a lower resolution
is displayed on the screen. This means that most people will be
able to see these additional refreshes - bad news.
To get rid of this flicker effect, you can upgrade to the
NEC 4D or get the SEIKO CM-1450 or the Sony 1304.
Richard
c60c-1gd@e260-3c.berkeley.edu (Joon Song) (09/30/90)
In article <1990Sep28.235629.15785@rick.cs.ubc.ca> e4666881@rick.cs.ubc.ca (richard louie) writes: > > The NEC 3D should not be ran too long in 1024 x 768 mode >because of the feature referred to as interlaced. When a display >is interlaced, you will tend to see a flicker on the screen. This >flicker is caused by the monitor needing to refresh the display >to get the 1024 x 768 more often than when a lower resolution >is displayed on the screen. This means that most people will be >able to see these additional refreshes - bad news. This is incorrect. Interlaced displays are not refreshed more often than non-interlaced displays. In fact the opposite is closer to the truth. When a display is interlaced, only every other line on the screen is refreshed during each vertical pass. So it takes two vertical passes to refresh the entire display. The reason the display flickers is that the display is being refresh at only one-half the rate of a non-interlaced display. -Joon Song c60c-1gd@web.berkeley.edu
davidsen@sixhub.UUCP (Wm E. Davidsen Jr) (09/30/90)
Lot of misconception on this one.
e4666881@rick.cs.ubc.ca (richard louie) writes:
: The NEC 3D should not be ran too long in 1024 x 768 mode
: because of the feature referred to as interlaced. When a display
: is interlaced, you will tend to see a flicker on the screen. This
: flicker is caused by the monitor needing to refresh the display
: to get the 1024 x 768 more often than when a lower resolution
: is displayed on the screen.
and c60c-1gd@e260-3c.berkeley.edu (Joon Song) points out:
: This is incorrect. Interlaced displays are not refreshed more often than
: non-interlaced displays. In fact the opposite is closer to the truth. When
: a display is interlaced, only every other line on the screen is refreshed
: during each vertical pass. So it takes two vertical passes to refresh the
: entire display. The reason the display flickers is that the display is
: being refresh at only one-half the rate of a non-interlaced display.
Let me try to say what these people meant so it will be clear to those
who don't already understand it.
A monitor writes horizontal dots at an almost constant frequency. When
you have more raster lines the time to rewrite the whole screen is so
long that the phosphor dims before being rewritten, so that individual
dots brighten and dim.
When the time gets bad enough this becomes visible to even something
as insensitive as a human eye. What video card manufacturers do is to
write half the lines (every other line) in one pass vertically, then the
other half of the lines. This is called interlace.
If you don't interleave the screen seems to flicker as the top and
bottom alternate in being brighter. If you interleave alternate
adjacent rows become brighter. When both modes were common the
non-interleaved was called flicker and the interleaved was called
twinkle. Both are annoying.
There are a number of solutions. One is to use a slower phosphor,
which doesn't dim as fast. This means that a moving bright spot will
leave a "comet trail" after the spot, and that when the whole screen
changes the old image will fade rather than change cleanly. A radar
screen is an example of a long persistance phosphor.
You can also write the horizontal dots faster, so that you get back to
each dot before it fades enough to notice. That means that the monitor
and video board have to run faster, and will cost more, at least to buy.
If you can't do either of the preceding, one thing which helps is to
view the display in a low light level with the brightness turned down.
This is because the phosphor dims faster the brighter it is.
We used to have all these problems and solutions when we ran 80x50
back in the early PC days (about 1978) and had a choice of what
interleave and stuff to run.
--
bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
sysop *IX BBS and Public Access UNIX
moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -mephil@brahms.amd.com (Phil Ngai) (09/30/90)
In article <1990Sep29.200049.22028@agate.berkeley.edu> c60c-1gd@e260-3c.berkeley.edu (Joon Song) writes: |So it takes two vertical passes to refresh the |entire display. The reason the display flickers is that the display is |being refresh at only one-half the rate of a non-interlaced display. This is sort of true but also misleading. In the PC world, interlace only comes into play at a resolution of 1024x768. The non-interlaced systems generally refresh at a rate of 60 hz. All the interlaced systems I know about use the 8514 system, which is a frame rate of 43.5 hz and a field rate of 87 hz. So here is a case where the interlaced display does NOT refresh at half the rate of the non-interlaced display, since 43.5 is not half of 60. I understand what you mean but only because I already knew what you were trying to say. -- Phil Ngai, phil@amd.com {uunet,decwrl,ucbvax}!amdcad!phil The Sierra Club is trying to stop CA-237 from being made into a freeway.
jls@hsv3.UUCP (James Seidman) (10/01/90)
I'll add in my $0.02 on this one as well... In article <1990Sep28.235629.15785@rick.cs.ubc.ca> e4666881@rick.cs.ubc.ca (richard louie) writes: > The NEC 3D should not be ran too long in 1024 x 768 mode >because of the feature referred to as interlaced. This almost sounds as if you're implying that this can damage your monitor or something in some way. Of course this isn't true. The 3D is rated to handle interlace speeds just fine, for hours (days) on end. > To get rid of this flicker effect, you can upgrade to the >NEC 4D or get the SEIKO CM-1450 or the Sony 1304. This is the part which I've heard far too often and is really misleading. (I've even seen ads from monitor manufacturers which seem to try to perpetuate this myth, and even ones that imply that you can get "ergonomic" refresh rates just by using their monitors!) Many graphics cards out there *ONLY* support interlaced 1024x768 modes, for the reason that you don't have to run the card as fast to do it (meaning a less-expensive design). If you hook one of these up to a 4D, CM-1450, 1304, or any other monitor, you will *still* get an interlaced display. It's the card, not the monitor, which controls screen timings, and make sure your card can do 1024x768 non-interlaced before you plop down the big bucks for an expensive monitor. -- Jim Seidman (Drax), the accidental engineer. UUCP: ames!vsi1!headland!jls ARPA: jls%headland.UUCP@ames.nasa.arc.gov
stanojev@ee.rochester.edu (Bob Stanojevich) (10/02/90)
In article <5061@hsv3.UUCP> jls@headland.UUCP (James Seidman) writes: >I'll add in my $0.02 on this one as well... > >In article <1990Sep28.235629.15785@rick.cs.ubc.ca> e4666881@rick.cs.ubc.ca (richard louie) writes: >> The NEC 3D should not be ran too long in 1024 x 768 mode >>because of the feature referred to as interlaced. > >This almost sounds as if you're implying that this can damage your monitor >or something in some way. Of course this isn't true. The 3D is rated to >handle interlace speeds just fine, for hours (days) on end. > >> To get rid of this flicker effect, you can upgrade to the >>NEC 4D or get the SEIKO CM-1450 or the Sony 1304. > >This is the part which I've heard far too often and is really misleading. >(I've even seen ads from monitor manufacturers which seem to try to >perpetuate this myth, and even ones that imply that you can get "ergonomic" >refresh rates just by using their monitors!) Many graphics cards out there >*ONLY* support interlaced 1024x768 modes, for the reason that you don't >have to run the card as fast to do it (meaning a less-expensive design). >If you hook one of these up to a 4D, CM-1450, 1304, or any other monitor, >you will *still* get an interlaced display. It's the card, not the monitor, >which controls screen timings, and make sure your card can do 1024x768 >non-interlaced before you plop down the big bucks for an expensive monitor. >-- >Jim Seidman (Drax), the accidental engineer. >UUCP: ames!vsi1!headland!jls >ARPA: jls%headland.UUCP@ames.nasa.arc.gov I have SEIKO 1440 monitor, PLATINUM 1 meg SVGA board (made by ACT Inc.) and I am EXTREMELY picky about monitors. However, I must say that runnig Window 3.0 in 1024x768x256 mode I could not see any flicker what so ever. I used Windows Paint program to load 8-bit image and it worked fine. I have never before used interlaced monitor because I hate them but the combination I mentioned is really flicker free, to my surprise. I am not sure but it seems to me that there is no point to have non-interlaced monitor if the pixel clock frequency is smaller them 90Mhz since the refresh rate will be below 50Hz-55Hz what is considered minimum for any reasonable flicker free non-interlaced display. Many of high end displays have 66 - 70 Hz refresh rate and that requires pixel clock of 120 - 150 Mhz for megapixel display. So far almost all SVGA boards have clocks in the range of 40-50 Mhz. I can not see how they can achieve better refresh rate then 45-50Hz in non-interlaced mode with that clock speed.. -Bob Stanojevich -- ***************************************************************************** * DISCLAIMER: I am entirely responsible for the content of this document, * * however, I am entirely IRRESPONSIBLE for any grammatical and/or spelling * * errors that might be found in this document. *
jls@hsv3.UUCP (James Seidman) (10/03/90)
In article <1990Oct2.152122.25078@ee.rochester.edu> stanojev@ee.rochester.edu (Bob Stanojevich) writes: >I am not sure but it seems to me that there is no point to have non-interlaced >monitor if the pixel clock frequency is smaller them 90Mhz since the >refresh rate will be below 50Hz-55Hz what is considered minimum for any >reasonable flicker free non-interlaced display. Many of high end displays >have 66 - 70 Hz refresh rate and that requires pixel clock of 120 - 150 Mhz >for megapixel display. You certainly don't need clocks that high! As a rough order of magnitude for clock speeds, you can use this formula: (horiz. resolution) * (vert. resolution) * (frame rate) * 1.33 = (pixel clock) In any case, there's a big advantage to having a 60 Hz non-interlaced display over an interlaced one at 88 Hz. And this 60 Hz 1024x768 display can be done at a mere 65 MHz pixel clock. >So far almost all SVGA boards have clocks in the >range of 40-50 Mhz. I can not see how they can achieve better refresh rate >then 45-50Hz in non-interlaced mode with that clock speed.. I'll strongly disagree with this one. Names that I can come up with off my head which have greater than 50 MHz clocks on their SVGA boards are Video-7, Orchid, Everex, Sigma, WDI, and ATI. (Many manufacturers are missing here, as I said these are off the top of my head.)-- Jim Seidman (Drax), the accidental engineer. "There's a certain freedom to being completely screwed." - The Freshman UUCP: ames!vsi1!headland!jls ARPA: jls%headland.UUCP@ames.nasa.arc.gov
stanojev@ee.rochester.edu (Bob Stanojevich) (10/03/90)
In article <5099@hsv3.UUCP> jls@headland.UUCP (James Seidman) writes: >In article <1990Oct2.152122.25078@ee.rochester.edu> stanojev@ee.rochester.edu (Bob Stanojevich) writes: >>I am not sure but it seems to me that there is no point to have non-interlaced >>monitor if the pixel clock frequency is smaller them 90Mhz since the >>refresh rate will be below 50Hz-55Hz what is considered minimum for any >>reasonable flicker free non-interlaced display. Many of high end displays >>have 66 - 70 Hz refresh rate and that requires pixel clock of 120 - 150 Mhz >>for megapixel display. > >You certainly don't need clocks that high! As a rough order of magnitude >for clock speeds, you can use this formula: > >(horiz. resolution) * (vert. resolution) * (frame rate) * 1.33 = (pixel clock) Of course everybody knows that formula so lets use it for SUN high res monitor 1600 * 1280 * 60 * 1.33 = 163.43 Mhz so you are talling that "You certainly don't need clocks that high". I was not refering only to the SVGA. The Sony 30" monitor for 2000x2000 pixels has 350 Mhz bandwidth ($30,000 price tag). > >In any case, there's a big advantage to having a 60 Hz non-interlaced display >over an interlaced one at 88 Hz. And this 60 Hz 1024x768 display can be >done at a mere 65 MHz pixel clock. That is the point. I thought the same but what is the "big advantage"? You have not explained that. I used to not even consider interlaced as an option. I got the board-monitor combination mentioned above and was really surprised that the sharpness was excelent and I could not see the flicker. That is why I posted the article because for SVGA resolution I can not see that "big advantage" over interlaced. > >>So far almost all SVGA boards have clocks in the >>range of 40-50 Mhz. I can not see how they can achieve better refresh rate >>then 45-50Hz in non-interlaced mode with that clock speed.. > >I'll strongly disagree with this one. Names that I can come up with off >my head which have greater than 50 MHz clocks on their SVGA boards are >Video-7, Orchid, Everex, Sigma, WDI, and ATI. (Many manufacturers are >missing here, as I said these are off the top of my head.)-- I am not claiming I have seen all the SVGA borads but do you claim from top off you head or you know defacto from the specks? In June this year I know that in SVGA (1024x768) mode nither ATI nor WDI had non-interlaced becuase we were looking to buy one and we could not get. We were told to by Orchid ProDesign if we want non-interlaced board by the resaler. -- ***************************************************************************** * DISCLAIMER: I am entirely responsible for the content of this document, * * however, I am entirely IRRESPONSIBLE for any grammatical and/or spelling * * errors that might be found in this document. *
oppenhei@umd5.umd.edu (Richard Oppenheimer) (10/13/90)
And now for my $0.02 :-) In article <5061@hsv3.UUCP> you write: >I'll add in my $0.02 on this one as well... > >In article <1990Sep28.235629.15785@rick.cs.ubc.ca> e4666881@rick.cs.ubc.ca (richard louie) writes: >> The NEC 3D should not be ran too long in 1024 x 768 mode >>because of the feature referred to as interlaced. > >This almost sounds as if you're implying that this can damage your monitor >or something in some way. Of course this isn't true. The 3D is rated to >handle interlace speeds just fine, for hours (days) on end. > >> To get rid of this flicker effect, you can upgrade to the >>NEC 4D or get the SEIKO CM-1450 or the Sony 1304. > >This is the part which I've heard far too often and is really misleading. >(I've even seen ads from monitor manufacturers which seem to try to >perpetuate this myth, and even ones that imply that you can get "ergonomic" >refresh rates just by using their monitors!) Many graphics cards out there >*ONLY* support interlaced 1024x768 modes, for the reason that you don't >have to run the card as fast to do it (meaning a less-expensive design). >If you hook one of these up to a 4D, CM-1450, 1304, or any other monitor, >you will *still* get an interlaced display. It's the card, not the monitor, >which controls screen timings, and make sure your card can do 1024x768 >non-interlaced before you plop down the big bucks for an expensive monitor. And some cards won't go down in speed to run in interlaced mode. An example of these "non-interlaced" cards is the Video-7 VRAM from Headland. Put the VRAM and the NEC 3D together and you can't do 1024x768 at all even though both the card and the monitor are rated for that res. The card wants to go fast (non-interlaced), but the monitor wants to go slow (interlaced). So when you are searching for a video subsystem to get you a certain res., make sure when the board and the monitor are put together they can truly deliver. The VRAM is a great card, but needs the NEC 4D or 5D. The 3D is a great monitor, but it needs a 8514/A type card. Now this is not to say that the 3D and the VRAM can't make music together. They do perform nicely at 800x600x256 or lower. Happy Hunting. -- Computer Science Center Richard Oppenheimer University of Maryland oppenhei@umd5.umd.edu (office) College Park, Maryland ,USA richard@wam.umd.edu (home) ****** My employer cares not what I think and knows not what I say. ******** -- Computer Science Center Richard Oppenheimer University of Maryland oppenhei@umd5.umd.edu (office) College Park, Maryland ,USA richard@wam.umd.edu (home) ****** My employer cares not what I think and knows not what I say. ********