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I'm not sure if defaulting to 32-bit instructions would still allow calling BIOS, but good point! In this case the design goal was to show the easiest way to j

by qx89l4 7y ago

I'm not sure if defaulting to 32-bit instructions would still allow calling BIOS, but good point! In this case the design goal was to show the easiest way to jump into C and start building the actual application, so I just tried to avoid any trickery (even enabling the A20 line)

PixelOfDeath 7y ago
You just set your chosen segment register(s) in protect mode, jump back to real mode, and then can use this segment register(s) in combination with the 32bit prefix to make a 32 bit memory access. All other segment registers are untouched and you can call into the bios just fine.