TTL monochrome video output

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  • April 18, 2012 at 4:52 am #434
    quarterturn
    Member

    I see the sync chip has H and V sync outputs, and TTL video is otherwise pretty similar to NTSC… so how difficult would it be to use the video experimenter to drive a TTL 15 kHz monitor?

    I have a nice 5″ Kristel TTL monitor from http://www.timeline-inc.com I’d like to use.

    Thank you!

    April 19, 2012 at 1:14 pm #876
    Michael
    Keymaster

    I’m afraid I have no experience with TTL video (never heard of it). If the timings are the same as NTSC, then maybe it will work.

    April 19, 2012 at 1:53 pm #877
    quarterturn
    Member

    The monitor I have is 15 kHz horizontal scan rate so I guess that’s basically the CGA standard, only in monochrome (640×200). I think that’s also NTSC in non-interlaced mode.

    April 24, 2012 at 6:29 pm #893
    quarterturn
    Member

    I think I have found the answer:
    http://www.epanorama.net/documents/vga2rgb/vgamonitor.html

    It describes the LM1881N plus a few log gates to get a true hsync. With that I should be able to drive my TTL monitor using a composite video signal.

    I have a teensy++ 2.0 which has 8k RAM. Timing issues aside, that ought to be good for at least 256×192. That will allow for a 40×24 line display, assuming 5×7 characters with 1 pixel spacing between them.

    July 16, 2012 at 7:43 am #961
    FidelStokes
    Member

    I think that’s also NTSC in non-interlaced mode.

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