Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
Dont' assume it's already set, some never bioses have an option to enable the a20 by default, but never assume that this will be set, always check it and set it appropriately, there are plenty of tutorials on how to do this.
Lprogster wrote:In 16bit (real) mode can you use EAX?
No, not in real mode. In 16 bit protected mode you can. But just replace it with AX. It should work.
Yes, in real mode you can use 32-bit instructions. The assembler will simply add prefixes to tell the processor that the next instruction uses 32-bit operands instead of the standard 16 bit ones.
Some bios functions return values in EAX and other 32-bit registers, and Unreal mode wouldnt exist if you couldnt use 32-bit addresses in real mode.
"Certainly avoid yourself. He is a newbie and might not realize it. You'll hate his code deeply a few years down the road." - Sortie
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Lprogster wrote:In 16bit (real) mode can you use EAX?
No, not in real mode. In 16 bit protected mode you can. But just replace it with AX. It should work.
Yes, in real mode you can use 32-bit instructions. The assembler will simply add prefixes to tell the processor that the next instruction uses 32-bit operands instead of the standard 16 bit ones.
Some bios functions return values in EAX and other 32-bit registers, and Unreal mode wouldnt exist if you couldnt use 32-bit addresses in real mode.
Okay, my fault, I thought it was only for 16 bit protected mode. Very nice indeed.
