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assembly language questions.

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sagar474

sagar474

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I found this in an article and I cant understand. why?
"If a valid boot sector is found, it is loaded into memory at location 0:07C0h. "

and I'm trying to understand the code.
Code: 
mov ax, 07C0h		; Set up 4K stack space after this bootloader
	add ax, 288		; (4096 + 512) / 16 bytes per paragraph
	mov ss, ax
	mov sp, 4096

	mov ax, 07C0h		; Set data segment to where we're loaded
	mov ds, ax
but i cant understand why 07C0h , why 288 ,why 4096

please anyone explain me this.
 

$07c0 is the memory location where the BIOS puts the bootloader.

288 = (4096 + 512) / 16 bytes per paragraph = 4k stack + 512 bytes for bootloader divided into 16-bit words.
 

288 = (4096 + 512) / 16 bytes per paragraph = 4k stack + 512 bytes for bootloader divided into 16-bit words.
Click to expand...
The explanation doesn't fit. The stack space is above SS, so the stack size doesn't matter for the register offset. May be an additional 4k data space is provided between code and stack. Or the author was simply confused.
 

Yes, I noticed that too.. I don't pretend to understand the code, but that is certainly how the author came up with the figure 288.
 

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