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Thanks,
Lprogster

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.

Thankyou Ready4Dis.

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Thanks,
Lprogster

You might want to read this: http://osdever.net/tutorials/pdf/a20.pdf

Thankyou for that Walling.

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Thanks,
Lprogster

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.

I hope you figure it out

I think Ive got t working... Thankyou everyone!

Thanks,
Lprogster

Walling wrote:

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.

Combuster wrote:

Walling wrote:

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.