; **************************************************************************** ; ; TRDOSB1.ASM ; ; Turkish Rational DOS ; Disk Operation System v1.0 Project ; 1.44 MB Floppy Disk FAT12 Boot Sector (Bootable Disk) Code ; ; Copyright (C) 2005 Erdogan TAN [ Last Modification: 31/07/2011 ] ; ; 13/05/2005 ; ; **************************************************************************** notvalidfmask equ 0018h root_dir_buff equ 0700h rts_segment equ 1010h FAT_Buffer equ 0700h RxDOSBOOT SEGMENT PUBLIC 'CODE' assume cs:RxDOSBOOT, ds:RxDOSBOOT, es:RxDOSBOOT, ss:RxDOSBOOT org 7C00h ;±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±± ;± ;± PROCEDURE proc_start ;± ;±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±± proc_start proc near BootSector: jmp short loc_2 nop ; BootSector Identification (Data) Block bsOemName db 'TRDOS1.0' bsBytesPerSec dw 512 bsSecPerClust db 1 bsResSectors dw 1 bsFATs db 2 bsRootDirEnts dw 224 bsSectors dw 2880 bsMedia db 0F0h bsFATsecs dw 9 bsSecPerTrack dw 18 bsHeads dw 2 bsHidden1 dw 0 bsHidden2 dw 0 bsHugeSectors dd 2880 bsDriveNumber db 0 bsReserved1 db 0 bsBpbSignature db 29h bsVolumeID dd 0 bsVolumeLabel db 'NO NAME ' bsFileSysType db 'FAT12 ' bsReserved2 dw 'RT' loc_2: xor AX, AX push cs pop ds push ds pop es cli push es pop ss mov sp, 0FFFEh sti loc_3: mov DL, byte ptr bsDriveNumber int 13h ; BIOS Service func ( ah ) = 0 ; Reset disk system jc short loc_ioerr ; To print i/o error message ; AX = 0 no error loc_4: mov AX, 19 ; Root Dir Location mov CX, 14 ; Root Directory Sectors mov BX, root_dir_buff ; Destination offset = 700h mov SI, BX call proc_read loc_5: jc short loc_ioerr ; Disk read error message mov BX, 224 ; Number of root dir entries loc_6: cmp Byte Ptr [SI],0 ; Is it null entry? je short loc_filenotfound ; Jump if zero ( = ) mov CX, 0Bh ; Size of file/directory name push SI mov DI, rtsfilename repe cmpsb ; Repeat if ZF = 1, CX > 0 ; Cmp byte at DS:SI to ES:DI pop SI je short loc_rtsfile_found ; If the file name found dec BX jz short loc_filenotfound ; Jump if no next entry add SI, 32 ; To next directory entry jmp short loc_6 ; Jump for next sector loc_filenotfound: mov SI, offset Replace_Msg jmp short loc_10 loc_ioerr: mov SI, offset Error_Msg loc_10: call proc_printmsg xor AX,AX int 16h ; BIOS Service func ( ah ) = 0 ; Read next kbd char ;AH-scan code AL-char code int 19h ; Reboot loc_rtsfile_found: mov AL, Byte Ptr [SI+0Bh] ; Move attributes byte to BL and AL, notvalidfmask ; Is it a file, really? ja short loc_filenotfound ; Jump if above ( > ) mov AX, Word Ptr [SI+1Ah] ; First cluster of the file cmp AX, 2 ; Start cluster jb short loc_ioerr mov Word Ptr [bsReserved2], AX ; Save the first cluster ; for using by the Kernel loc_load_FAT: mov AX, 1 ; FAT Location mov CX, 9 ; FAT Sectors mov BX, FAT_Buffer call proc_read jc short loc_ioerr loc_load_rtsfile: mov si, offset Loading_Msg call proc_printmsg mov AX, word ptr [bsReserved2] ; The First cluster mov BX, rts_segment mov ES, BX xor BX, BX call proc_load_file jc short loc_ioerr loc_launch_rts: mov dl, byte ptr [bsDriveNumber] mov ax, 1000h mov ds, ax mov es, ax cli mov ss, ax mov sp, 0FFFEh sti mov ax, 417 ; MASM.EXE don't accept ; jmp 1000h:0100h ; for OP Code: EA00010010 db 0EAh dw 0100h dw 1000h proc_start endp proc_printmsg proc near loc_9: lodsb ; Load byte at DS:SI to AL and AL, AL jnz short loc_write_char ; If AL = 00h then stop retn loc_write_char: mov AH, 0Eh mov BX, 07h int 10h ; BIOS Service func ( ah ) = 0Eh ; Write char as TTY ;AL-char BH-page BL-color jmp short loc_9 proc_printmsg endp proc_read proc near ; Only for FAT12 Floppy Disks (18 sector/track) mov byte ptr [RetryCount], 4 loop_loc_14: push CX push AX ; PHYSICAL ADRESS CALCULATION mov CL, 18 ; Sectors per track div CL mov CL, AH ; Sector (zero based) inc CL ; To make it 1 based xor AH, AH mov DL, 2 ; Heads div DL ; AL=cyl, AH=head, CL=sector mov DH, AH mov DL, byte Ptr bsDriveNumber mov CH, AL mov AX,0201h int 13h ; BIOS Service func ( ah ) = 2 ; Read disk sectors ;AL-sec num CH-track CL-sec ; DH-head DL-drive ES:BX-buffer ;CF-flag AH-stat AL-sec read pop AX pop CX jc short loc_16 inc AX loc_15: dec CX jz short loc_17 add BX, 512 mov byte ptr [RetryCount], 4 jmp short loop_loc_14 loc_16: dec byte ptr [RetryCount] jnz short loop_loc_14 stc loc_17: retn proc_read endp proc_load_file proc near ; ES:BX = File Buffer ; AX = First Cluster Number ; Only for FAT12 Floppy Disks (1 sector per cluster) loc_load_file_next_cluster: mov word ptr [File_Cluster], ax mov word ptr [File_BufferOff], bx dec ax ; First cluster is cluster 2 dec ax mov cx, 1 ; Sector count add ax, 33 ; Beginning sector of Data call proc_read jc short loc_load_file_retn loc_cont_load_file: mov ax, word ptr [File_Cluster] call proc_get_next_cluster jnc short loc_cont_load_file_2 cmp ax, 1 cmc loc_load_file_retn: retn loc_cont_load_file_2: mov bx, word ptr [File_BufferOff] add bx, 512 jmp short loc_load_file_next_cluster proc_load_file endp proc_get_next_cluster proc near ; INPUT -> AX = Cluster Number ; OUTPUT -> clc -> No Error, AX = Next Cluster ; OUTPUT -> stc & AX=0 -> End Of Cluster Chain ; OUTPUT -> stc & AX>0 -> Error get_FAT12_next_cluster: mov bx, ax mov dx, 3 mul dx shr ax, 1 ; Divide by 2 xchg bx, ax ; BX = Buffer Byte Offset ; AX = Current Cluster mov ax, word ptr [FAT_Buffer][BX] jnc short get_FAT12_nc_even shr ax, 1 shr ax, 1 shr ax, 1 shr ax, 1 loc_gnc_fat12_eoc_check: cmp ax, 0FF7h jc short loc_pass_gnc_FAT12_eoc_check xor ax, ax loc_pass_gnc_FAT12_eoc_check: cmc retn get_FAT12_nc_even: and ah, 0Fh jmp short loc_gnc_fat12_eoc_check proc_get_next_cluster endp File_Cluster: dw 0 File_BufferOff: dw 0 rtsfilename: db 'TRDOS COM' db 0 Error_Msg: db 0Dh, 0Ah db 'TRDOS Loading Error!' Replace_Msg: db 0Dh, 0Ah db 'Replace the disk and press any key to reboot.' db 0Dh, 0Ah,0 Loading_Msg: db 0Dh, 0Ah ; 30/07/2011 db "Loading Operating System TRDOS ..." db 0Dh, 0Ah, 0 RetryCount: db 1 dup(0) org 7DFEh bootsignature: db 55h, 0AAh RxDOSBOOT ends end BootSector