flat assembler
Message board for the users of flat assembler.
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joachim_neu 06 Aug 2005, 07:47
As far as I know setting up a IDT isn't realy required. There's another step not required by the CPU directly, reprogramming the PIC. Else you'll get all the IRQs in exceptions...
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Dex4u 06 Aug 2005, 11:21
You do not need A20 to go to pmode, but you will not be able to use the full 4GB of memory,
Code: org 0x7C00use16;****************************; Realmode startup code.;****************************start: xor ax,ax mov ds,ax mov es,ax mov ss,ax mov sp,0x7C00;*****************************; Setting up, to enter pmode.;***************************** cli lgdt [gdtr] mov eax, cr0 or al,0x1 mov cr0,eax jmp 0x10: protected;*****************************; Pmode. Th is about the smallist code for go to pmode, you can even take out the turn floppy motor off to make it smaller ![]() |
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SouthernMunk 07 Aug 2005, 00:24
Cool, thanks!
Quote:
So how much memory can you access? Surely more than the 1MB used by Real Mode, as memory addressing is calculated differently. Because setting up the IDT is not necessary for entering PMode, there's less code required to enter Long Mode! Yay! Thanks for the responses, guys! ![]() |
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Dex4u 07 Aug 2005, 12:54
Every other MB.
As for long mode this bit of code may help, as it goes to long mode from real mode, its for yasm not fasm ![]()
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Night Rider 07 Aug 2005, 16:21
Quote:
16 Mb |
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