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Error Executing FAT16 bootsector
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ata0-master: type=disk, path="D:\Stuff\projs\Nasm\FAT\fat16_6.img", mode=flat, cylinders=40, heads=16, spt=63, model="Generic 1234", biosdetect=auto, translation=auto

; Skip over the data portion of the "DOS BOOT RECORD". The install method
; must merge the code from this ASM with the data put in the boot record
; by the FAT16 formatter.
;
;times 0x3B db 0

;minimal, default BIOS Parameter Block (BPB)

oem_id: ; 03h not used by this code
db "GEEZER", 0, 0

bytes_per_sector: ; 0Bh
dw 512

sc_p_clu: ; 0Dh
db 64 ; maximum (2 gig partition)

sc_b4_fat:; 0Eh
dw 1

fats: ; 10h
db 2

dir_ent: ; 11h
dw 512

total_sectors: ; 13h not used by this code
dw 0

media_id: ; 15h not used by this code
db 0F8h

sc_p_fat: ; 16h
dw 256 ; maximum (2 gig partition)

sc_p_trk: ; 18h
dw 63 ; maximum (2 gig partition)

heads:; 1Ah
dw 255 ; maximum (2 gig partition)

sc_b4_prt: ; 1Ch
dd 16065 ; partition 1 (CHS=1:0:1)

total_sectors_large: ; 20h not used by this code
dd 4192965 ; CHS=261:255:63 (2 gig partition)

drive: dw 80 ; 0x24
Signiture: db 0 ; 0x26
VolSerial: dd 0 ; 0x27
VolLabel: db "12345678901" ; 0x2B
SysId: db "12345" ; 0x36

vbguyny wrote:After putting some "magic breakpoints" into the boot loader I see that the int 13h call doesn't error but it isn't populating the memory with the sector from the disk. Instead the segment that I expect to be populated contains all zeros. This causes the boot loader to not find my kernel.

read_32:
;
; Input:
; dx:di = sector within partition
; bl = sector count (max 0x80)
; es = destination segment
;
; The sector number is converted from a partition-relative to a whole-disk
; (LBN) value, and then converted to CHS form, and then the sectors are read
; into ES:0.
;
; Output:
; di = input di + input bx
; bx = 0
; dl = drive
; si, bp and seg regs unchanged
; other registers modified

lea ax, [di+bx] ;Compute di+bx (needed by two caller's
push ax ; of read_16)

add di, [sc_b4_prt] ;Convert to LBN
adc dx, [sc_b4_prt+2]

xchg ax, dx ;AX = (high) LBN
cwd
div word [sc_p_trk] ; / Sectors per track
xchg ax, di ;AX = (low) LBN ;DI = (high) track
div word [sc_p_trk] ;AX = (low) track ;DX = sector-1
inc dx
mov cl, dl ;CL = sector
mov dx, di ;DX = (high) track
div word [heads] ; / Number of heads
mov dh, dl ;DH = head

mov ch, al ;CH = (low) cylinder
ror ah, 1 ;rotate (high) cylinder
ror ah, 1
add cl, ah ;CL = combine sector, (high) cylinder
mov dl, [drive] ;DL = Drive number
xchg ax, bx ;AL = Sector count
mov ah, 2 ;AH = Read command
xor bx, bx ;ES:BX = address
xchg bx, bx ; Magic breakpoint
int 13h ;Do it
jc error.2
pop di ;DI = Input DI + Input BX
ret

vbguyny wrote:cylinders=40, heads=16, spt=63,

vbguyny wrote:@SpyderTL: I would like to write it myself however I am not able to find any good tutorials on this. It seems that the internet favors FAT12 for hobbyist boot loaders. Do you have any suggestions?

vbguyny wrote:@Octocontrabass: Thanks for your suggestions. The problem is that I don't know what the correct values need to be in the BPB in order to get this working. In my previous post I tried to hard code them to 2GB but it didn't make a difference (Although this was copied from something I found on the internet).

Also I tried 4 other boot loaders and none of them work so I think that there is something wrong with the formatting of the drive or the BPB. Does anyone know of a good utility that I can use to create hard drive images? I am using bximage right now.

ata0-master: type=disk, path="D:\Stuff\projs\Nasm\FAT\fat16_9.img", mode=flat, cylinders=65, heads=16, spt=63, model="Generic 1234", biosdetect=auto, translation=auto

partcopy boot16.bin 0 3 -ai
partcopy boot16.bin 3e 1c2 -ai 3e