OSDev.org

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BITS 16

jmp start			;jump to actual executing code

;------------------------------message set to display on the screen--------------
wellcome_msg db 'welcome to Sagar cool new operating system',13,10,0,
reboot_msg db   'Your system is going to reboot now....',13,10,0,
reboot_key	db 'Press any key to reboot',13,10,0,
resetmsg	db 'Press any key to reset flopy',13,10,0,
reset_success 	db 'reset successful',13,10,0,
read_sectors    db 'Press any key to read sector',13,10,0
read_success  	db 'Sector read successful....',13,10,0,


;------------------------------Main Boot loading process starts hear---------------
	start:
	mov ax, 07C0h		; Set data segment to where we're loaded
	mov ds, ax		; 
	mov ax,9000h		;initlise the stack 
	mov ss,ax		;
	mov sp,100h		;
	
	mov si,wellcome_msg	;source index rigester (SI) ponits to the wellcome_message offset
	call print		;call the print subrotine. 
	
	mov si,resetmsg
	call print
	call getkey
	mov si,reset_success
	call print
	
	mov si,read_sectors
	call print
	call getkey
	call read_sector

	
	mov si,512;
	call print
		
	

	mov si,reboot_key	; SI points to the off set of the string with lable reboot_key
	call print		;call the prit subrotine.
	
	call getkey
	



	mov si,reboot_msg	;SI points to offset of the string with lable reboot_msg
	call print		;call the print subrotine.
	
	call reboot		;reboots the system.
	


	jmp $			; jump hear ie., infinite loop



;------------------------sub rotine---------------------------------------------
;----------------------to print string ------------------------------------------	
	print:			;print subrotine
	mov ah,0eh;		;loads ah with 0eh function for print char in BIOS int 10h
	repet:			;
	lodsb			;al<-----[si] and si=si+1 
	cmp al,0		;compair al and 0
	je done			;if al=0 then jump to lable don
	int 10h;		;call BIOS intrupt 10h video services
	jmp repet		;unconditional jump to lable repit:
	done:
	ret			;return to main program.
;-------------------------------------------------------------------------------------		

;------------------------key board input------------------------------------------------
getkey:
mov ah,0			;functaion for keyboard char input stors ASCII value in al
int 16h				;BIOS keyboard intrupt 
ret
;-------------------------------------------------------------------------------------

;---------------------------reboot-----------------------------------------------------
     reboot:

                db 0EAh                 ; machine language to jump to FFFF:0000 (reboot)
                dw 0000h
                dw 0FFFFh
                ; no ret required; we're rebooting! (Hey, I just saved a byte :)
;--------------------------------------------------------------------------------------

;--------------------------reset flopy-------------------------------------------------
Reset_flopy:
.reset
mov dl,0;drive 0 is flopy drive
mov ah,0;reset flopy disk functation
int 13h; call BIOS
jc .reset
ret

;---------------------------------------------------------------------------------------
;---------------------------read sectors------------------------------------------------

read_sector:
mov ax,0x1000
mov es,ax
xor bx,bx

.read:
mov ah,0x02
mov al,1
mov ch,0
mov cl,2
mov dh,0
mov dl,1
int 0x13

jc  .read

jmp 0x1000:0x0
ret
;---------------------------------------------------------------------------------------
	
times 510-($-$$) db 0	; Pad remainder of boot sector with 0s
	dw 0xAA55		; The standard PC boot signature
jmp sec ;sector 2
newsector db 'Im the new sector',13,10,0,

sec: 
mov si,newsector
	mov ah,0eh;		;loads ah with 0eh function for print char in BIOS int 10h
	re:			;
	lodsb			;al<-----[si] and si=si+1 
	cmp al,0		;compair al and 0
	je did			;if al=0 then jump to lable don
	int 10h;		;call BIOS intrupt 10h video services
	jmp re		;unconditional jump to lable repit:
	did:

Code: Select all

read_sector:
mov ax,0x1000
mov es,ax
xor bx,bx

.read:
mov ah,0x02
mov al,1
mov ch,0
mov cl,2
mov dh,0
mov dl,1
int 0x13

jc  .read