• A2VGA - Pico IIe Card / A2VGA - Pico IIc Card

    From Lukazi@21:1/5 to All on Sun May 28 02:14:50 2023
    Hi all,

    I'm building a budget Apple IIe/IIc VGA card that most people will be able to put together by themselves.

    https://lukazi.blogspot.com/2023/05/a2vga-pico-iie-card.html.

    I'm trying to cement which video signal pins to be used before I build the next revision of the hardware. I prefer to get this correct now then find a surprise later.

    From the IIe Aux port or IIc Video port - Pins needed:
    14M: Apple II video clock
    SEROUT : Luma part of the video signal ie the monochrome pixel bitstream.
    WNDW: Start of the picture being displayed.

    Pins also included:
    GR: Sets up each line to display in colour or monochrome.

    Pins considering:
    SYNC: Start of line at the left hand border. May become useful for VSync. Alternate to WNDW signal.
    LDPS: Helpful to realign 80 and 40 column modes.
    VIDD7: Can be used to implement Combined Colour/Mono mode (was popular on RGB cards). I've just posted details with pictures on this signal here https://www.applefritter.com/content/apple-ii-video-hdmi-using-raspberry-pi-zero-pico.

    Pins excluded:
    CREF: Colour reference. Great for discrete component based video cards but not required on microcontroller based video cards since CREF is just 14M/4.

    For those who have done Apple II video stuff before, is there any other signals which you have used/considered and why?

    Thanks
    Alex.

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