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Thread: "most useful" Apple II+ cards?

  1. #11

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    Quote Originally Posted by iz8dwf View Post
    Well, of course my //c is the euro version. I have never seen colors out of it But it was free, so I don't complain.
    I could easily make a PAL adapter on the video port, but I've never really needed colors so far. Apple IIe was in my school and that was mostly for programming. At home I had a VIC-20 first then a C64, and these had colors
    What RGB card do you recommend for the ][ anyway?
    Frank
    Ciao. Nowadays I do recommend NTSC monitor because NTSC TVs are scrapped and almost free and are still widespread. I doubt you can make PAL color adapter "easily" on the videoport. The level of complexity would be at least that of the Apple2 PAL card which schematic is published in the literature. I have //e PAL clones and original Apple //e PAL version and I can say I am not impressed by their PAL output. Generally PAL has twice lower color resolution than NTSC as far as I remember and is not good for computer generated images.
    Last edited by george; October 9th, 2019 at 11:51 PM.

  2. #12

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    Quote Originally Posted by george View Post
    Ciao. These days I do recommend NTSC monitor because NTSC TVs are scrapped and almost free and are still widespread. I doubt you can make PAL color adapter "easily" on the videoport. The level of complexity would be at least that of the Apple2 PAL card which schematic is published in the literature. I have //e PAL clones and original Apple //e PAL version and I can say I am not impressed by their PAL output. Generally PAL has twice lower color resolution than NTSC as far as I remember and is not good for computer generated images.
    That level of complexity is what I call easy. After all, I'm an electronic engineer, graduated when university was an harder place to live than today's one
    And well, PAL was invented precisely because NTSC color rendition was let's say "imperfect". However, correct PAL signals need the proper PAL monitors/TVs. I'm not sure a NTSC C64 for example would have better colors than a PAL C64 (since I only have seen PAL ones in my life).
    It only seems to me that Apple cheated with the NTSC color signal in the first place and it wasn't possible to make the more complex PAL color modulation with the same tricks. European versions should have been sold with the additional PAL card as a free option if they really thought it was absolutely vital to have a color output, but at least in Italy, the Apple II was never famous to be a game machine (it was way too expensive for anything at the typical homes). Apple II were machine found in offices, schools and small business. In the '80s I have seen lots of them (and even asked to make some programs for it) and I have never seen one connected to a color monitor.
    Frank

  3. #13

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    I am an engineer too. If I were you I would have called that "easy" when I had successfully built a working prototype. Do you presently FULLY understand how this PAL card schematics works even being an engineer yourself? I doubt it. Yes, to repeat someone else's published schematic is usually easy. But one don't have to be an engineer to do that. NTSC has better vertical color resolution but its color is vulnerable to distortions and therefore NTSC TV sets have "hue" controls. That was corrected in PAL via it's alternating phase and vector summing from two consecutive scan lines (previous line is memorized in a 64 uS delay line in decoders).

    Here is wiki more popular explanation concerning PAL's resolution...

    The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, which automatically corrects phase errors in the transmission of the signal by cancelling them out, at the expense of vertical frame colour resolution.
    A minor drawback is that the vertical colour resolution is poorer than the NTSC system's, but since the human eye also has a colour resolution that is much lower than its brightness resolution, this effect is not visible.
    (https://en.wikipedia.org/wiki/PAL)

    I dare say PAL artifacts are quite visible on computer generated screens especially when these screens are as usually watched at much shorter distances compared to TV broadcasts. In addition many NTSC artifacts were exploited by Apple2 programmers to realize some visual effects of their taste which are not displayed as intended with PAL.
    Last edited by george; October 10th, 2019 at 12:24 AM.

  4. #14

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    You're missing my point: to me an Apple II of any kind has been always been a monochrome machine. And yes, I do know quite a bit on how PAL works (having for example fully restored a Philips PM-5508 ).
    We also can't debate much if PAL or NTSC look better as I've really never seen a NTSC output computer and having one isn't on my list at the moment. There're probably different artifacts and programmers have been known for exploiting every one they could.
    Frank

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