We need precise control over Hz and kHz and also monitor specs

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Don't Panic. Please wash hands.

    Using a CVisionPPC here.

    I need to have precise control over frequencies in order have a resolution without screen tearing. Can this be done?


    Quote

    59.94005233 for NTSC and 50.00028194 for PAL


    In order to have a stable resolution without screen tearing and jumpy mouse & solid window movement on an Amiga with Pal timings, the rtg resolution needs to be multiples of 50.00028194 Hz. But the only way to change vertical freq is to use the clock slider and that is not very precise. It increases the number in huge chunks and even then, we can not see the precise frequencies.

    Also it would be very helpful if there was a way to input the specs of our monitors. For example my Philips 201B4 has the following:


    • Horizontal Scanning 30 - 115 kHz
    • Vertical Scanning 50 - 160 Hz

    • Video Dot Rate 261 MHz

    • Input Impedance
    -Video 75Ω
    -Sync 2.2kΩ
    • Input Signal Levels 0.7 Vp-p

    So in order have the perfect resolution with smooth moving objects and without screen tearing, I need to have a rtg resolution with one of the following horizontal frequencies:


    50,00028194 Hz

    100,00056388 Hz

    150,00084582 Hz

    The 50,00028194hz flickers too much on VGA monitors. So this leaves me with 100,xxx for high resolutions and 150,xxx for low ones.

    We won't be able to deliver on this request, as the crystals on the gfx card and the Amiga crystal are not synchronized. You'd only be able to sync the two outputs if one of them uses a PLL to lock to the other one. What would be the application?

    Unfortunately, VGA chips of the time are not as flexible as what we can do with Indivision AGA MK3 and Indivision ECS V2. Precision is not limited by software, but by the VGA hardware - there's nothing we can so about a limited choice of pixel clock. It's just not in the VGA standard.

    I found the time to reassemble my Amiga (no time too much work) and used my iphone to upload a 60hz video to show what happens;

    the screenmode is 1024x768 at 59hz. (64.431810Mhz) and screen tearing can be observed when moving stuff around. If I decrease pixel clock with one click to 63,984366 Mhz the screen tearing movement changes direction to upwards.

    https://drive.google.com/file/…TM0uN/view?usp=drive_link