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Bochs VBE Extensions: Difference between revisions
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== Overview ==
The Bochs emulated graphics hardware (henceforth called BGA for Bochs Graphics Adaptor) is accessed via two 16-bit IO-ports. The first one is an index port, the second one a data port (comparable to how the VGA handles its sets of registers). Via these ports it is possible to enable or disable the VBE extensions, change the screen resolution and bit depth, and manage a larger virtual screen. There are five versions of the BGA (0xB0C0 through 0xB0C4), but if you use the latest version of Bochs you only need to concern yourself with the latest one (0xB0C4). QEMU (with the -std-vga command line argument) also
The Bochs sources define in vga.h, located in the subdirectory iodev/, a number of defines that are useful for programming the BGA. The names of these defines all start with VBE_DISPI. They are used in the sections below, with their numerical value between parentheses.
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