; Boot sector for floppy disk (720k/1.44M, FAT12);%define KERNEL_START_SEG	0x2000[BITS 16][ORG 0x7C00]Base:	jmp short Begin	nopoem             db 'OrzMicro' 		; OEM IDbytesPerSector  dw 0x0200		; Bytes per sectorsectPerCluster  db 0x02			; Sectors per clusterresSectors      dw 0x01			; Reserved sectors at beginningfatCopies       db 0x02			; Fat copiesrootEntCnt      dw 0x0070		; Root directory entriestotalSectors    dw 0x05A0		; Total sectors on diskmedia           db 0xF9			; Media descriptor bytesectPerFat      dw 0x0003		; Sectors per FATsectPerTrack    dw 0x0009		; Sectors per trackheads           dw 0x0002		; HeadshiddenSectors   dd 0			; Special hidden sectorssectorHuge      dd 0drive           db 0			; Physical drive number		db 0extendedBPB     db 0x29			; Extended boot record signaturevolumeID        dd 0			; Volume serial numbervolumeLabel     db 'Orz Disk   '	; Volume labelfileSys         db 'FAT12   '		; File system ID;------------------------------------------------------------------------Begin:	cli			; Init	cld	mov ax,cs	mov ds,ax	mov ss,ax	mov sp,7c00h	sti	mov [curDrive],dl   	; get current drive from BIOS;----------------------------------------------- 	mov ax,$03	int $10	mov ax,$0B800	mov es,ax	xor di,di	mov si,fname	mov ah,$2F	call Print;-----------------------------------------------; Get Drive Params;-----------------------------------------------		mov si,[hiddenSectors]		mov di,[hiddenSectors+2]		add si,[resSectors]		adc di,0		; DI:SI = first FAT sector		mov [fatStart],si		mov [fatStart+2],di		mov al,[fatCopies]		xor ah,ah		mul WORD [sectPerFat]	; DX:AX = total sectors in FATs		add si,ax		adc di,dx		; DI:SI = first ROOT sector		mov [rootStart],si		mov [rootStart+2],di		mov ax,[rootEntCnt]		mov cl,5		; TODO: reminding yet?		shl ax,5		xor dx,dx		div WORD [bytesPerSector]		mov [secPerRoot],ax		add si,ax		adc di,0		; DI:SI = first data sector		mov [dataStart],si		mov [dataStart+2],di;-----------------------------------------------; Find File;-----------------------------------------------		mov ax,$1000		mov es,ax		mov ax,[rootStart]		mov dx,[rootStart+2]		mov cx,[secPerRoot]		xor bx,bx		call ReadSectors		xor di,di		; ES:DI, DS:SIFindFile0:	mov cx,11		mov si,fname		push di		repe cmpsb		pop di		mov ax,[es:di+$1A]	; cluster number		jz FindFile1		add di,$20		; next dir entry		cmp BYTE [es:di],0	; this is end of root?		jnz FindFile0		jmp PrintErrorFindFile1:;-----------------------------------------------; Get FAT Chain;-----------------------------------------------		push ax		mov ax,$1000		mov es,ax		xor bx,bx		mov cx,[sectPerFat]		mov ax,[fatStart]		mov dx,[fatStart+2]		call ReadSectors		pop ax		push ds		;		push es		; swap (DS, ES)		pop ds		;		pop es		;		mov di,fatBufGetFatChain0:	stosw		; WORD [ES:DI] = AX, DI += (DF==0)?(2):(-2)		; use following code only for FAT12		mov si,ax		add si,si		add si,ax		shr si,1	; SI = (AX * 3) / 2, (-*-)		lodsw		; AX = WORD [DS:SI], SI += (DF==0)?(2):(-2)		jnc GetFatChain1	; (-*-)		mov cl,4		shr ax,clGetFatChain1:	and ah,$0F		cmp ax,$0FF8	; This is EOC? (>= 0x0FF8)		jc GetFatChain0		xor ax,ax		stosw		push cs		; Restore DS		pop ds;-----------------------------------------------; Load File;-----------------------------------------------		mov ax,KERNEL_START_SEG		mov es,ax		xor bx,bx		mov si,fatBufLoadFile0:	lodsw		; AX = WORD [DS:SI], SI += (DF==0)?(2):(-2)		and ax,ax		jz RunemAll		dec ax		dec ax		; clusters numbers start from 2		mov cl,[sectPerCluster]		xor ch,ch		mul cx		add ax,[dataStart]		adc dx,[dataStart+2]		call ReadSectors		push es		mov ax,$0B800		mov es,ax		mov di,160ll0:   		mov WORD [es:di], $072E    		inc di    		inc di    		mov [cs:ll0-2], di		pop es		jmp short LoadFile0;-----------------------------------------------RunemAll:	mov ax,$0B800		mov es,ax		mov di,320		mov si,msg_ok		mov ah,14		call Print		mov dl,[drive]		mov ax,KERNEL_START_SEG		mov ds,ax		mov es,ax		jmp WORD KERNEL_START_SEG:0000;------------------------------------------------------------------------PrintError:    	mov si,err_notfound		mov ax,$0B800		mov es,ax		mov di,160		mov ah,$4C		call PrintPrintError1:	jmp short PrintError1;------------------------------------------------------------------------; SI = szText, ES:DI = screen_address, AH = colorPrint:		mov al,[cs:si]		and al,al		jz Print0		mov [es:di],al		inc di		mov [es:di],ah		inc di		inc si		jmp short PrintPrint0:		ret;------------------------------------------------------------------------; DX:AX = first_sector_LBA, ES:BX = buffer, CX = numReadReadSectors:	push ax		push dx		push cx		push es		push bx		call ReadSector		pop bx		pop es		add bx,[bytesPerSector]		jnc ReadSectors1		mov ax,es		add ah,$10		mov es,axReadSectors1:	pop cx		pop dx		pop ax		add ax,1		adc dx,0		loop ReadSectors		ret; DX:AX = sector_LBA, ES:BX = bufferReadSector:	div WORD [sectPerTrack]		inc dl			; sector = 1 + sector_LBA % sectPerTrack		mov cl, dl     		; CL = sector		xor dx,dx		div WORD [heads]	; head = (sector_LBA/sectPerTrack) % heads		mov dh,dl		; DH = head		mov ch,al		; cyl = (sector_LBA/sectPerTrack) / heads, CH = cyl		mov dl,[curDrive]	; DL = drive		mov ax,$0201		int $13		jc PrintError		ret;------------------------------------------------------------------------		;   12345678extfname		db "ORZKERNL   ",0err_notfound	db "Err",0msg_ok		db "OK",0;------------------------------------------------------------------------EndOfBase		times (0x01FE-(EndOfBase-Base)) db 0		dw 0xAA55curDrive  	equ $		; db 0fatStart	equ $+1		; dd 0rootStart	equ $+5		; dd 0secPerRoot	equ $+9		; dw 0dataStart	equ $+11	; dd 0fatBuf		equ $+15