4 ms·
>> they only work in the real-address mode Presumably it would work just fine in the "Unreal mode"[1] - one which is very similar to real, with the added benef
by dexen 7y ago
>> they only work in the real-address mode
Presumably it would work just fine in the "Unreal mode"[1] - one which is very similar to real, with the added benefit of being 32bit address space, and 32bit instructions by default
[1] https://en.wikipedia.org/wiki/Unreal_mode https://en.wikipedia.org/wiki/Unreal_mode
- qx89l4 7y agoI'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 agoYou 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.