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Add explanation about -2

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Eric Semeniuc 2018-12-23 18:34:20 -08:00 committed by GitHub
parent 7aff64740e
commit 910ada89f0
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1 changed files with 2 additions and 2 deletions
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04-bootsector-stack/boot_sect_stack.asm
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@ -3,12 +3,12 @@ mov ah, 0x0e ; tty mode
mov bp, 0x8000 ; this is an address far away from 0x7c00 so that we don't get overwritten
mov sp, bp ; if the stack is empty then sp points to bp
push 'A'
push 'A' ; pushes 2 bytes onto the top of the stack since the CPU is in 16bit mode
push 'B'
push 'C'
; to show how the stack grows downwards
mov al, [0x7ffe] ; 0x8000 - 2
mov al, [0x7ffe] ; 0x8000 - 2 (each character takes 2 bytes due to 16bit boundaries)
int 0x10
; however, don't try to access [0x8000] now, because it won't work