TV for ZX Spectrum

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  • Nothing beats a CRT TV for authenticity and “feel.” A CRT monitor works fine, but seems a little bit like cheating.

    From a developer’s perspective, a CRT TV is especially useful, as most (all?) emulators don’t reproduce the colors and brightness levels correctly, so testing your game on an actual Spectrum hooked up to a CRT TV is a must. Kind of like a pair of good near-field monitors in a treated room for sound mixing.
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
  • "What TV or monitor you use with your ZX Spectrum ?"

    Are your assuming that I have my original ZX hooked up?
    Or do you mean, when I fire up an emu, what sort of a screen do I use?
    What now?
  • I need know how much users use LCD/LED TV with real ZX Spectrum/clones
  • Well, for 128k machines I go for RGB (digital or analogue) on an old CRT monitor.

    48K machines I have them linked to CRT monitor or CRT TV via s-video because I can't stand dot crawl anymore. Plus, it is ideal to have luma connected to green/cyan/amber monitors rather than CVBS for dealing with text.
  • Please test also this files on ZX:
    https://velesoft.speccy.cz/other/hiexol.zip (if hi-res graphic is incorrect then press and release key)
    https://velesoft.speccy.cz/other/dizzy8gigascreen.zip

    If may test your ZX with LCD/LED TV then may be both pictures without flickering/stable. Please test if it's possible and inform me is graphic is stable on TV.
  • I don’t believe your program does what you intend it to do. First, you’re toggling the wrong bit. Second, that’s not the correct way of paging in RAM banks (you’re not updating the system variable at 23388). Third, BASIC is probably too slow for this. Fourth, in principle, you won’t be able to avoid flicker no matter how hard you try using this method.
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
  • edited May 2018
    I don’t believe your program does what you intend it to do. First, you’re toggling the wrong bit. Second, that’s not the correct way of paging in RAM banks (you’re not updating the system variable at 23388). Third, BASIC is probably too slow for this. Fourth, in principle, you won’t be able to avoid flicker no matter how hard you try using this method.

    1) no, I use correct bit D3 on port 7FFD for videoram switching. Tested and work. On real ZX with LCD TV
    2) sorry, program must be loaded in USR0 mode (or from DIVIDE/DIVMMC - this device use USR0 mode)
    3) no, this way use only easy videoram switching each interrupt (= 50x per second) then in basic is all ok, same as play AY music routines from basic.
    4) no, some tested pieces of LCD TV show ZX screens only at 25Hz. Each two zx screens are used as EVEN+ODD screen frame and visible as one stable picture on LCD. Both zx screens are visible parallel on TV screen, only interlaced (second screen is about 0.5pixels shifted down). This way enable also stable HI-RES mode 256x384...

    All is tested with more users and on real hardware.

    Screen flickering is often visible on CRT TV or small LCD panels with low resolution. Ideal is TV in full-hd or 720p

    Post edited by velesoft on
  • edited May 2018
    velesoft wrote: »
    2) sorry, program must be loaded in USR0 mode (or from DIVIDE/DIVMMC - this device use USR0 mode)
    Okay. You probably should have specified this in your post with the tests. It’s kind of a game changer. ;)
    Post edited by Ast_A_Moore on
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
  • More info on Facebook group "Spectrum For Everyone"
    https://facebook.com/groups/spectrumforeveryone/permalink/616854665327675/

    Or search on some ZX groups on FB this "show on LCD TV full static picture without flickering"

    On FB you can see more photos and videos.
  • I’m not on Facebook.
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
  • I will today upload all photos on my website and release here
  • EXAMPLE OF GRAPHIC ON LCD TV (don't need any CPU time !!!)

    Modified game graphic in Dizzy 8 (sprite without attribute collisions)
    IMG_20180428_205437.jpg

    Small color text with outline
    IMG_20180402_152108.jpg
    IMG_20180402_152104.jpg
    IMG_20180403_172846.jpg

    up to 128 colors on screen
    IMG_20180331_130402.jpg

    interlaced screen on LCD TV
    IMG_20180402_011557.jpg

    example of color pixels without attribute collisions
    IMG_20180402_185703.jpg

  • Example of HI-RES graphic in mode 256x384
    IMG_20180501_160610.jpg
    IMG_20180501_160555.jpg
  • I've just bought myself a new TV! And by "new", I mean "eight years old from the British Heart Foundation shop". Fact is, my old 37" flat-screen had only one HDMI port and it failed about four years ago, so I've only been able to watch the few HD channels I have through a SCART port in SD - though that's still better than watching the SD channels with all the blocky MPEG artifacts. The new TV is a mere 32" but has four HDMI ports... and two RGB-capable SCARTs.

    This is, so I would think, good news for my collection of Spectrums. I can have the +2 in one port and the black models in the other port, seeing as they need a different RGB lead. Or, at least, that was the idea. The black models all work fine in either port... but the +2 doesn't. On the old 37" TV I'd get a reasonably static picture, only I'd notice that it would occasionally jump from side to side, only by a pixel or so. This was quite annoying, but tolerable if it didn't do it too much. On the new 32" TV, it's thrashing around all over the place - the picture's obviously sharp, but it's completely unusable. As I only have the one +2 I can't test whether it's the RGB cable that's at fault, or the +2 itself - though, knowing that the +2 has rather more faults than I'd previously thought after all the investigations I did last year, I'd assume it was the +2 playing up.
  • Some flat screens cannot handle the RGB from the scart lead, my Matsui screens (HD ready) gives the same results as you describe, jumping all over the place. Testing it with a Samsung Full HD, it is perfect. The Bush Full HD is also perfect and also gives sound over the RGB lead when the sound lead is not plugged in!
    If you've already done the composite fix in the grey +2 then make a lead and use that instead, I know it is not as good as RGB, but it is a whole lot better than the RF.

    Glad to know that I'm not the only one that buys second hand stuff and will make do with what is available.

    Back to the original post....
    Tested on my grey +2 in USR 0 mode.
    Great as the pictures are, they do have a slight flicker to them on all the screens as listed above, both in RGB and Composite mode. Maybe it is refresh rate of my screens or just something more. I'll have to dig around the TV settings and see if they can be changed.
  • edited May 2018
    I use a Philips LED TV however my zx spectrum is modified to use RCA video cable
    and not RF.
    The image is really good
    Post edited by hillelr on
  • Tried again on my Samsung HD TV with RGB scart lead and managed to get a flicker free image for the 'kick-ass' image. The Dizzy image works, but I'm not a fan of the black scan lines on the picture, I'm not keen with them on emulation either, so it's the first thing I switch off.
    Congratulations. Maybe it will work in games, but the overhead of writing to 2 screens and keeping things in sync might be a performance hit. Lets see how it goes.
  • edited May 2018
    MatGubbins wrote: »
    Tried again on my Samsung HD TV with RGB scart lead and managed to get a flicker free image for the 'kick-ass' image. The Dizzy image works, but I'm not a fan of the black scan lines on the picture, I'm not keen with them on emulation either, so it's the first thing I switch off.
    Congratulations. Maybe it will work in games, but the overhead of writing to 2 screens and keeping things in sync might be a performance hit. Lets see how it goes.

    What TV model you use ?
    Yes, true, on dizzy screen you see similar effect as scanlines, but this picture is only for testing. Games may be without defects and with high resolution. :-)
    Post edited by velesoft on
  • The black models all work fine in either port... but the +2 doesn't. On the old 37" TV I'd get a reasonably static picture, only I'd notice that it would occasionally jump from side to side, only by a pixel or so. This was quite annoying, but tolerable if it didn't do it too much. On the new 32" TV, it's thrashing around all over the place - the picture's obviously sharp, but it's completely unusable.

    Have you changed the motherboard links over to SCART compatible mode to make it use the same pinout as the black +2, and changed the appropriate resistors? If not, do that, and I'm 99% confident that will cure any problems you have with SCART.
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • Next example of static screen on LCD TV
    interlace2.jpg

    Sprite in editor
    interlace1.jpg
  • And here is snapshot with small graphic example:
    https://velesoft.speccy.cz/other/scrmix2.Z80
  • edited May 2018
    velesoft wrote: »
    Please test also this files on ZX:
    https://velesoft.speccy.cz/other/hiexol.zip (if hi-res graphic is incorrect then press and release key)
    https://velesoft.speccy.cz/other/dizzy8gigascreen.zip

    If may test your ZX with LCD/LED TV then may be both pictures without flickering/stable. Please test if it's possible and inform me is graphic is stable on TV.

    I've tested the Dizzy image on a 32" LCD-TV and on a 24" LED-TV, using ZXBaremulator with HDMI mode 576i@50 Hz. The image is stable and without flickering on both TV sets:

    LED-TV

    LCD-TV
    Post edited by zx81 on
  • edited May 2018
    Post edited by velesoft on
  • there's a game for gigascreen if you wanna check
    http://www.worldofspectrum.org/infoseekid.cgi?id=0027929
    TRD only though
  • Next example of modified game screen:
    lcd2.png

    Z80 snapshot for testing on real ZX with LCD TV
    https://velesoft.speccy.cz/other/lcd2.zip
  • velesoft wrote: »
    Next example of modified game screen:
    Nope, won't work for the real game, too much colours for such a tiny sprite. Two colours per background tile, just white for the sprites, that will do. That's beside the fact the actual game, being made with AGD, uses xored sprites.
  • In interlaced mode (gigascreen) is possible in each area 8x8 pixels place 4 colors. LCD TV show this as stable picture. Main player sprite is in original game xored and is white, but here I use all 4 colors as example what is possible with interlaced screen... And is not so big problem with small software support place up to 6 colors to one area 8x8 without any drastic CPU timing...
  • edited May 2018
    Here is photo of my LCD TV:
    lcd2-final.jpg

    And here is previous version with white/original sprite
    lcd2-test.jpg
    Post edited by velesoft on
  • @velesoft: well done & keep going.
  • And photo of two russian games:
    IMG_20180527_160819.jpg
    IMG_20180527_160252.jpg
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