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; This is a comment
[ORG 0x7C00] ;This just tells the program where it is in the memory. Not important
[BITS 16] ;Not important too.

jmp start		; Jump over BIOS parameter block

start: ;The label for the start of the actual program

push cs ;Put cs onto the stack
pop ds ;Take it out and put it into ds


mov si,Print_loading     ;Print loading message
call printstring		 ;Call is like jump, but it goes back. Like a function


						 ;The complicated bit: Loads the next program
mov ah,02h               ;When ah=, int13 reads a disk sector
mov al,4			 	 ;Al is how many sectors to read
mov ch,0			 	 ;The track to read from
mov cl,2			 	 ;Sector Id
mov dh,0			 	 ;Head
mov dl,0			 	 ;Drive (0 is floppy)
mov bx,0x1000			 ;Es and Bx put together are where to load the program too (see jmp 0x1000:0x00)
mov es,bx
mov bx,0x00
int 13h					;Int 13 is all functions for disks

mov si,putdot           ;Print a ".".
call printstring

jmp 0x1000:0x00         ;Run Bootinit from stack.

printstring:            ;Print string routine.
mov ah,0eh				;Mov ah into 0, so int 10 prints
stringloop:				;The following code loads each seperate charcter so it can be printed
lodsb					
cmp al,00				;If al =0, then the string has all been loaded
je endstring
int 10h					;When int 10 is called, and ah=, it prints
jmp stringloop
endstring:
ret						;Ret returns



putdot        db '.',0
Print_loading db 13,10,'Loading Pure OS v0.01a...',0
times 425 db 0 ;wastes 425 bytes on purpose, so the sector is full (The program must be 512 bytes long)