HI!
I have a big problem. I found this asm-code on a site, and want to run it.
---- CODE ----
; NYAOS Boot Sector (C) Copyright Sean Tash 1998
; assemble with:
; nasm -f bin -o bootsect.bin bootsect.asm
bits 16
org 0x7C00
start: jmp short begin
nop
bsOEM db "NYAOS1.0" ; OEM String
bsSectSize dw 512 ; Bytes per sector
bsClustSize db 1 ; Sectors per cluster
bsRessect dw 1 ; # of reserved sectors
bsFatCnt db 2 ; # of fat copies
bsRootSize dw 224 ; size of root directory
bsTotalSect dw 2880 ; total # of sectors if < 32 meg
bsMedia db 0xF0 ; Media Descriptor
bsFatSize dw 9 ; Size of each FAT
bsTrackSect dw 18 ; Sectors per track
bsHeadCnt dw 2 ; number of read-write heads
bsHidenSect dd 0 ; number of hidden sectors
bsHugeSect dd 0 ; if bsTotalSect is 0 this value is
; the number of sectors
bsBootDrv db 0 ; holds drive that the bs came from
bsReserv db 0 ; not used for anything
bsBootSign db 29h ; boot signature 29h
bsVolID dd 0 ; Disk volume ID also used for temp
; sector # / # sectors to load
bsVoLabel db "NO NAME " ; Volume Label
bsFSType db "FAT12 " ; File System type
begin: cli ; disable interrupts
mov [bsBootDrv],dl ; save drive number
mov ax,0x9000 ; put stack at 0x98000
mov ss,ax
mov sp,0x8000
mov cx,[bsTrackSect] ; update int 1E FDC param table
mov bx,0x0078
lds si,[ds:bx]
mov byte [si+4], cl
mov byte [si+9], 0x0F
sti ; enable interrupts
push ds
mov dl,[bsBootDrv] ; reset controller
xor ax,ax
int 0x13
pop ds
jc bootfail2 ; display error message
jmp _l1
bootfail2: jmp bootfail
_l1:
mov ax,0x0000
mov es,ax
mov ds,ax
mov si,MsgLoad ; display load message
call putstr
; find the root directory
xor ax,ax
mov al,[bsFatCnt]
mov bx,[bsFatSize]
mul bx
add ax,word [bsHidenSect]
adc ax,word [bsHidenSect+2]
add ax,word [bsRessect] ; ax holds root directory location
mov word [BootSig],ax
call checkroot
xor ax,ax
add ax,word [start]
add ax,word [bsVolID] ; sector number
add ax,word [BootSig]
sub ax,2 ; correction for a mis-calc
mov cx,word [bsVolID+2] ; number of sectors
mov bx,0x8000
mov es,bx
nextsector: push ax ; save registers
push cx
push dx
push es
xor bx,bx ; set zero offset
call readsect ; read a sector
mov si,MsgDot ; display a dot
call putstr
pop es ; restore registers
pop dx
pop cx
pop ax
mov bx,es
add bx,20h ; increment address 512 bytes
mov es,bx
inc ax ; read next sector
loopnz nextsector
mov ax,0x8000 ; set segment registers and jump
mov es,ax
mov ds,ax
push ax
mov ax,0
push ax
retf
checkroot:
push ax ; save registers
push bx
push cx
push dx
push si
push di
mov ax,0x8000 ; put root directory at 0x80000
mov es,ax
mov ax,32 ; AX = ((32*RootSize)/512) + 2
mul word [bsRootSize]
div word [bsSectSize]
mov cx,ax ; cx holds # of sectors in root
mov word [start],ax
mov ax,word [BootSig] ; get prev. saved loc. for root dir
r1: xor bx,bx
push cx ; save count
push ax ; save sector number
push es
push dx
call readsect
xor bx,bx
l_1: mov di,bx ; set address to check from
mov cx,11 ; check 11 bytes
mov si,FileName ; address of string to check with
repz cmpsb
je foundit
add bx,32 ; check next entry
cmp bx,[bsSectSize] ; end of sector?
je l_2
jmp l_1
l_2: pop dx ; restore registers
pop es
pop ax
pop cx
inc ax ; read next sector
loopnz r1
jmp bootfail
foundit: pop dx ; get these off the stack
pop es
pop ax
pop cx
mov di,0x1A ; get clustor #
add di,bx
push bx ; save bx for finding # of sectors
mov ax,[es:di]
xor bx,bx ; calculate sector #
mov bl,[bsClustSize]
mul bx ; ax holds sector #
mov word [bsVolID],ax
pop bx ; get location of directory entry
mov di,0x1C
add di,bx
mov ax,[es:di] ; put number of bytes in ax
xor dx,dx
mov bx,[bsClustSize] ; # of bytes / 512
div bx
inc ax
mov word [bsVolID+2],ax ; save number of sectors to load
pop di ; restore registers
pop si
pop dx
pop cx
pop bx
pop ax
ret ; return to caller
putstr: ; SI = address of string to display
lodsb
or al,al
jz short putstrd
mov ah,0x0E
mov bx,0x0007
int 0x10
jmp putstr
putstrd: retn ; return to caller
bootfail: ; display failure message
mov si,MsgBad ; display error message
call putstr
xor ax,ax ; wait for keypress
int 0x16
int 0x19 ; reboot
readsect: ; ES:BX = Location ; AX = Sector
mov si,[bsTrackSect]
div si ; divide logical sect by track size
inc dl ; sector # begins at 1
mov [bsReserv],dl ; sector to read
xor dx,dx ; logical track left in ax
div word [bsHeadCnt] ; leaves head in dl, cyl in ax
mov dh, [bsBootDrv] ;
xchg dl,dh ; head to dh, drive to dl
mov cx,ax ; cyl to cx
xchg cl,ch ; low 8 bits of cyl to ch, hi 2 bits
shl cl,6 ; shifted to bits 6 and 7
or cl, byte [bsReserv] ; or with sector number
mov al,1 ; number of sectors
mov ah,2 ; use read function of int 0x13
int 0x13 ; read sector
jc bootfail ; display error message
ret ; return to caller
padding times 45 db 0
FileName db "OSLOADERCOM"
MsgBad db "Disk Error...",13,10,0
MsgDot db ".",0
MsgLoad db "doors loading",0
BootSig db 0x55, 0xAA
---- CODE ----
It load the file osloader.com on the floppy disk. It function with a demo pogram. I have programmed a lot of com-programms, but my programms don't function with this bootloader. Can anybody help me? Thank you very much.
big thx Turbo24prg
FAT12 bootloader loads com-program
-
carbonBased
RE:FAT12 bootloader loads com-program
Is your com program OS independant? Does it use DOS interrupts?
Could you be more specific as to the problem you're having? Is there an error message, does it reboot? If so, where? etc, etc
Jeff
Could you be more specific as to the problem you're having? Is there an error message, does it reboot? If so, where? etc, etc
Jeff
-
Turbo24prg
RE:FAT12 bootloader loads com-program
the bootloader normaly does load the prog osloader.com. I have a demo programm that prints a lot of colors on the screen. it is written in asm. my c programm that i wrote is a totorial on the "bonafide os development site". the tutorial "making a simple c kernel" doesn't function. I have written a simple c prog that use the adress 0x8b000 to print a text on screnn.
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DRF
RE:FAT12 bootloader loads com-program
Could you please paste the code for the demo program and the code your program (kernel) so we can compare and point out any errors.
If you are using a C compiler you may be having problems with using pmode commands within a real mode booted system.
(Using 32bit commands in a 16bit initlising boot sector)
Also double check that you don't try to use a DOS/linux/Windows specific interrupt or command.
Hope this helps, unfortunatly I don't have time to look over the boot loader in detail to point out ant more hints.
Daniel aka DRF
If you are using a C compiler you may be having problems with using pmode commands within a real mode booted system.
(Using 32bit commands in a 16bit initlising boot sector)
Also double check that you don't try to use a DOS/linux/Windows specific interrupt or command.
Hope this helps, unfortunatly I don't have time to look over the boot loader in detail to point out ant more hints.
Daniel aka DRF