• Jim
  • Yokemate of Keyboards
    Yokemate of Keyboards
    Jim
    Posts: 4956 from 2009/1/28
    From: Delaware, USA
    Quote:

    Andreas_Wolf wrote:
    > considering the fact that we now have support for cards with 512MB or more
    > (up to 2GB) of vram, this limitation shouldn't exist.

    As I wrote in comment #52 (and if I'm not mistaken), MorphOS still can only use up to 256 MiB VRAM because RAM + VRAM must fit into 31-bit address space. Or has this changed with MorphOS 3.10 or 3.11?


    Interesting issue. We map vram into address space?
    I must admit, I am not that familiar with how Amiga related OS' use RTG cards.

    When we were writing drivers for VGA cards under OS9 68K, graphics were not mapped into processor space.
    But I can see why this would be natural with an Amiga related OS as legacy Amigas mapped video in chipram.

    In fact, I always like memory mapped video, even when it was something crude like the VDG used in Tandy Color Computers.

    VDPs that mapped through a window like the TMS9918 were more difficult to code for.

    Still, I'm left wonder how vram can be mapped like this when it's accessed through a bus (PCI, AGP, PCIe, etc).
    "Never attribute to malice what can more readily explained by incompetence"
  • »06.09.18 - 19:22
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