4 ms·

A lot of those CRT screens had a pretty low refresh frequency, you were basically sitting in front of a giant stroboscope. That was particular bad for computer

by cm2187 10mo ago

A lot of those CRT screens had a pretty low refresh frequency, you were basically sitting in front of a giant stroboscope. That was particular bad for computer screens where you were sitting right in front of them. I think they pretty much all displayed at 30Hz. I can imagine how a gigantic screen can get pretty uncomfortable.

sprayk 10mo ago
all CRTs televisions were either 60Hz or 50Hz depending on where you are in the world
- cm2187 10mo ago
  Yes and no. Half of the screen was refreshing at a time, so it was really flashing at 30Hz. You still had a visible stroboscopic effect. True 60Hz and 100Hz screen appeared in the late 90s and made a visible difference in term of comfort of viewing.
  - mabster 10mo ago
    I'm guessing you're talking about interlacing? I've never really experienced it because I've always watched PAL which doesn't have that. But I would have thought it would be perceived as flashing at 60 Hz with a darker image?
    - pledg 10mo ago
      PAL had interlacing
      - walkerbrown 10mo ago
        For anyone this deep on the thread, check out this video (great presenter!) explaining TV spectrum allocation, NTSC, PAL, and the origin of 29.97 fps. https://youtu.be/3GJUM6pCpew https://youtu.be/3GJUM6pCpew
        DonHopkins 10mo ago
        TIL NTSC: He explained that NTSC stands for Not The Smartest Choice, but I always assumed it meant Never The Same Color.
      - mabster 10mo ago
        Memories shattered. Yeah, you're right and I would have watched interlaced broadcast content. I saw interlaced NTSC video in the digital days where the combing was much more obvious and always assumed it was only an NTSC thing!
  - SoftTalker 10mo ago
    Yeah I remember I could not use a CRT computer monitor at 60Hz or less for any length of time, as the strobing gave me a headache.
  - ntoskrnl_exe 10mo ago
    I think you're mixing monitors and TVs together. CRT TVs only supported vertical refresh rates of 50Hz or 60Hz, which matched the regional mains frequency. They used interlacing and technically only showed half the frame at a time, but thanks to phosphor decay this added a feeling of fluidity to the image. If you were able to see it strobe, you must have had an impressive sight. And even if they supported higher refresh rates, it wouldn't matter, as the source of the signal would only ever be 50/60Hz. CRT monitors used in PCs, on the other hand, supported a variety of refresh rates. Only monitors for specific applications used interlacing, customer grade ones didn't, which means you could see a strobing effect here if you ran it at a low frequency. But even the most analog monitors from the 80s supported atleast 640x480 at 60Hz, some programs such as the original DOOM were even able to squeeze 70Hz out of them by running at a different resolution while matching the horizontal refresh rate.
    - myself248 10mo ago
      For some reason I remember 83Hz being the highest refresh rate supported by my XGA CRT, but I think it was only running at SVGA (800x600) in order to pull that rate. Some demos could throw pixels into VRAM that fast, and it was wild looking. Like the 60Hz soap-opera effect but even more so. I still feel that way looking at >30fps content since I really don't consume much of it.
    - pezezin 10mo ago
      > some programs such as the original DOOM were even able to squeeze 70Hz out of them by running at a different resolution while matching the horizontal refresh rate. 400p at 70 Hz was the default resolution of the VGA, pretty much all the classic mode 13h games ran at 70 Hz.
numpad0 10mo ago
Did they really do that, or did the tubes just ran at 2x vertically stretched 640x240 with vertical pixel shift? A lot of technical descriptions of CRTs seem to be adapted from pixel addressed LCDs/OLEDs, and they don't always seem to capture the design well
- wkat4242 10mo ago
  They did exactly what you say. Split the image and pixel shift. It was not like 30Hz at all.
  - numpad0 10mo ago
    Thanks, I wonder if the phosphor stripes are giving people false impression that those would be pixels...
ssl-3 10mo ago
Except CRT televisions weren't like that at all. The only time the electron gun was not involved in producing visible light was during overscan, horizontal retrace, and the vertical blanking interval. They spent the entire rest of their time (the very vast majority of their time) busily drawing rasterized images onto phosphors (with their own persistence!) for display. This resulted in a behavior that was ridiculously dissimilar to a 30Hz strobe light.
mjg59 10mo ago
The limiting factor is the horizontal refresh frequency. TVs and older monitors were around 15.75kHz, so the maximum number of horizontal lines you could draw per second is around 15750. Divide that by 60 and you get 262.5, which is therefore the maximum vertical resolution (real world is lower for various reasons). CGA ran at 200 lines, so was safely possible with a 60Hz refresh rate. If you wanted more vertical resolution then you needed either a monitor with a higher horizontal refresh rate or you needed to reduce the effective vertical refresh rate. The former involved more expensive monitors, the latter was typically implemented by still having the CRT refresh at 60Hz but drawing alternate lines each refresh. This meant that the effective refresh rate was 30Hz, which is what you're alluding to. But the reason you're being downvoted is that at no point was the CRT running with a low refresh rate, and best practice was to use a mode that your monitor could display without interlace anyway. Even in the 80s, using interlace was rare.
- cm2187 10mo ago
  The irony is that most of those who downvote didn't spend hours in front of those screens as I did. And I do remember these things were tiring, particularly in the dark. And the worst of all were computer CRT screens, that weren't interlaced (in the mid 90s, before higher refresh frequency started showing up).
  - adrianmonk 10mo ago
    I spent literally thousands of hours staring at those screens. You have it backwards. Interlacing was worse in terms of refresh, not better. Interlacing is a trick that lets you sacrifice refresh rates to gain greater vertical resolution. The electron beam scans across the screen the same number of times per second either way. With interlacing, it alternates between even and odd rows. With NTSC, the beam scans across the screen 60 times per second. With NTSC non-interlaced, every pixel will be refreshed 60 times per second. With NTSC interlaced, every pixel will be refreshed 30 times per second since it only gets hit every other time. And of course the phosphors on the screen glow for a while after the electron beam hits them. It's the same phosphor, so in interlaced mode, because it's getting hit half as often, it will have more time to fade before it's hit again.
bob1029 10mo ago
I recall a lot of people playing counterstrike at 640x480 to get at 100+hz refresh rates. The lower the resolution, the faster you can refresh. I don't recall the absolute limit but it would give the latest LCD gaming panels a serious run for their money.
- utopcell 10mo ago
  In the meanwhile, oled monitors can go to 480hz.
  - db48x 10mo ago
    If you pay extra for that. Meanwhile _any_ CRT could trade off resolution for refresh rate across a fairly wide range. In fact the standard resolutions for monitors were all just individual points in a larger space of possibilities. They could change aspect ratio as well. This can be quite extreme. Consider the 8088 MPH demo from a few years back (<https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-all-your-emulators/ https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-al...>). See the part near the end with the pictures of 6 of the authors? That video mode only had 100 lines, but scrunched up to make a higher resolution.
    - utopcell 10mo ago
      Well, we are discussing a CRT TV that was $40k new a life time ago, so perhaps the fact that it costs $599 to get a 480Hz OLED today is not a consideration. To the point though: it is a fallacy to believe that CRTs could arbitrarily shape their resolution. While the input signal could cover a wide range of possible resolutions and refresh rates depending on the bandwidth supported, the existence of apperture grilles or shadow masks imposed a fixed digital reality that limited the maximum possible resolution to much lower values than the typical 4k panels that we have today. The "pixels" didn't become larger on lower resolutions: they just covered more dots on the mask. We can get much better results today with scaling than we ever could on CRTs, as awesome a technology as they were 40 years ago.
      - 10mo ago
anthk 10mo ago
I did 1024x768@85 just fine.
- Sunspark 10mo ago
  If it supported it, 100 Hz paired with a mouse set for 200 Hz was nice and smooth.

by cm2187 10mo ago

sprayk 10mo ago

all CRTs televisions were either 60Hz or 50Hz depending on where you are in the world

cm2187 10mo ago
Yes and no. Half of the screen was refreshing at a time, so it was really flashing at 30Hz. You still had a visible stroboscopic effect. True 60Hz and 100Hz screen appeared in the late 90s and made a visible difference in term of comfort of viewing.
- mabster 10mo ago
  I'm guessing you're talking about interlacing? I've never really experienced it because I've always watched PAL which doesn't have that. But I would have thought it would be perceived as flashing at 60 Hz with a darker image?
  - pledg 10mo ago
    PAL had interlacing
    - walkerbrown 10mo ago
      For anyone this deep on the thread, check out this video (great presenter!) explaining TV spectrum allocation, NTSC, PAL, and the origin of 29.97 fps. https://youtu.be/3GJUM6pCpew https://youtu.be/3GJUM6pCpew
      - DonHopkins 10mo ago
        TIL NTSC: He explained that NTSC stands for Not The Smartest Choice, but I always assumed it meant Never The Same Color.
    - mabster 10mo ago
      Memories shattered. Yeah, you're right and I would have watched interlaced broadcast content. I saw interlaced NTSC video in the digital days where the combing was much more obvious and always assumed it was only an NTSC thing!
- SoftTalker 10mo ago
  Yeah I remember I could not use a CRT computer monitor at 60Hz or less for any length of time, as the strobing gave me a headache.
- ntoskrnl_exe 10mo ago
  I think you're mixing monitors and TVs together. CRT TVs only supported vertical refresh rates of 50Hz or 60Hz, which matched the regional mains frequency. They used interlacing and technically only showed half the frame at a time, but thanks to phosphor decay this added a feeling of fluidity to the image. If you were able to see it strobe, you must have had an impressive sight. And even if they supported higher refresh rates, it wouldn't matter, as the source of the signal would only ever be 50/60Hz. CRT monitors used in PCs, on the other hand, supported a variety of refresh rates. Only monitors for specific applications used interlacing, customer grade ones didn't, which means you could see a strobing effect here if you ran it at a low frequency. But even the most analog monitors from the 80s supported atleast 640x480 at 60Hz, some programs such as the original DOOM were even able to squeeze 70Hz out of them by running at a different resolution while matching the horizontal refresh rate.
  - myself248 10mo ago
    For some reason I remember 83Hz being the highest refresh rate supported by my XGA CRT, but I think it was only running at SVGA (800x600) in order to pull that rate. Some demos could throw pixels into VRAM that fast, and it was wild looking. Like the 60Hz soap-opera effect but even more so. I still feel that way looking at >30fps content since I really don't consume much of it.
  - pezezin 10mo ago
    > some programs such as the original DOOM were even able to squeeze 70Hz out of them by running at a different resolution while matching the horizontal refresh rate. 400p at 70 Hz was the default resolution of the VGA, pretty much all the classic mode 13h games ran at 70 Hz.

numpad0 10mo ago

Did they really do that, or did the tubes just ran at 2x vertically stretched 640x240 with vertical pixel shift? A lot of technical descriptions of CRTs seem to be adapted from pixel addressed LCDs/OLEDs, and they don't always seem to capture the design well

wkat4242 10mo ago
They did exactly what you say. Split the image and pixel shift. It was not like 30Hz at all.
- numpad0 10mo ago
  Thanks, I wonder if the phosphor stripes are giving people false impression that those would be pixels...

ssl-3 10mo ago

Except CRT televisions weren't like that at all. The only time the electron gun was not involved in producing visible light was during overscan, horizontal retrace, and the vertical blanking interval. They spent the entire rest of their time (the very vast majority of their time) busily drawing rasterized images onto phosphors (with their own persistence!) for display. This resulted in a behavior that was ridiculously dissimilar to a 30Hz strobe light.

mjg59 10mo ago

The limiting factor is the horizontal refresh frequency. TVs and older monitors were around 15.75kHz, so the maximum number of horizontal lines you could draw per second is around 15750. Divide that by 60 and you get 262.5, which is therefore the maximum vertical resolution (real world is lower for various reasons). CGA ran at 200 lines, so was safely possible with a 60Hz refresh rate. If you wanted more vertical resolution then you needed either a monitor with a higher horizontal refresh rate or you needed to reduce the effective vertical refresh rate. The former involved more expensive monitors, the latter was typically implemented by still having the CRT refresh at 60Hz but drawing alternate lines each refresh. This meant that the effective refresh rate was 30Hz, which is what you're alluding to. But the reason you're being downvoted is that at no point was the CRT running with a low refresh rate, and best practice was to use a mode that your monitor could display without interlace anyway. Even in the 80s, using interlace was rare.

cm2187 10mo ago
The irony is that most of those who downvote didn't spend hours in front of those screens as I did. And I do remember these things were tiring, particularly in the dark. And the worst of all were computer CRT screens, that weren't interlaced (in the mid 90s, before higher refresh frequency started showing up).
- adrianmonk 10mo ago
  I spent literally thousands of hours staring at those screens. You have it backwards. Interlacing was worse in terms of refresh, not better. Interlacing is a trick that lets you sacrifice refresh rates to gain greater vertical resolution. The electron beam scans across the screen the same number of times per second either way. With interlacing, it alternates between even and odd rows. With NTSC, the beam scans across the screen 60 times per second. With NTSC non-interlaced, every pixel will be refreshed 60 times per second. With NTSC interlaced, every pixel will be refreshed 30 times per second since it only gets hit every other time. And of course the phosphors on the screen glow for a while after the electron beam hits them. It's the same phosphor, so in interlaced mode, because it's getting hit half as often, it will have more time to fade before it's hit again.

bob1029 10mo ago

I recall a lot of people playing counterstrike at 640x480 to get at 100+hz refresh rates. The lower the resolution, the faster you can refresh. I don't recall the absolute limit but it would give the latest LCD gaming panels a serious run for their money.

utopcell 10mo ago
In the meanwhile, oled monitors can go to 480hz.
- db48x 10mo ago
  If you pay extra for that. Meanwhile _any_ CRT could trade off resolution for refresh rate across a fairly wide range. In fact the standard resolutions for monitors were all just individual points in a larger space of possibilities. They could change aspect ratio as well. This can be quite extreme. Consider the 8088 MPH demo from a few years back (<https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-all-your-emulators/ https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-al...>). See the part near the end with the pictures of 6 of the authors? That video mode only had 100 lines, but scrunched up to make a higher resolution.
  - utopcell 10mo ago
    Well, we are discussing a CRT TV that was $40k new a life time ago, so perhaps the fact that it costs $599 to get a 480Hz OLED today is not a consideration. To the point though: it is a fallacy to believe that CRTs could arbitrarily shape their resolution. While the input signal could cover a wide range of possible resolutions and refresh rates depending on the bandwidth supported, the existence of apperture grilles or shadow masks imposed a fixed digital reality that limited the maximum possible resolution to much lower values than the typical 4k panels that we have today. The "pixels" didn't become larger on lower resolutions: they just covered more dots on the mask. We can get much better results today with scaling than we ever could on CRTs, as awesome a technology as they were 40 years ago.
    - 10mo ago

anthk 10mo ago

I did 1024x768@85 just fine.

Sunspark 10mo ago
If it supported it, 100 Hz paired with a mouse set for 200 Hz was nice and smooth.