Custom bootloader not working

Question

I have designed my custom bootloader (which showy my name only.) using assembly language and compiled it using NASM. Now I want to install it in USB.But not able to find any way for burning it. I have tested using different utilities like ISOtoUSB, Universal USB,rufus. Error is coming 'image is not bootable.'

But when I run the same on oracle virtual drive, it works perfectly.

I am doing some college project and strucked, I want to load that bootloader to usb and when I boot from usb, my bootloader should work.

Any idea please?

Here is my code:

[BITS 16]
[ORG 0x7C00]

main:
mov ax, 0x0000
mov ds,ax

mov si, string
call print
jmp $

print:
mov ah,0x0E
mov bh,0x00

.nextchar
lodsb
or al,al
jz .return
int 0x10
jmp .nextchar
.return
ret
string db 'Welcome to the Amul Bhatia Operating System Now Installing....',0
times 510-($-$$) db 0
dw 0AA55h

Answer 1

Even with the signature in place, you may find that some hardware will not boot your image. It seems that some BIOS implementations require a valid BPB (BIOS Parameter Block) to be present in your image.

You might consider replacing the first few lines of your boot loader with something like this:

bits 16

org 0                                   ; BIOS will load the MBR to this location.

bootStart:
                jmp             _start
                nop
                bootDrive       db      'MSDOS6.0'
                bpb
                bps                     dw      512
                spc                     db      8
                rs                      dw      1
                fats            db      2
                re                      dw      512
                ss                      dw      0
                media           db      0xf8
                spfat           dw      0xc900
                spt                     dw      0x3f00
                heads           dw      0x1000
                hidden          dw      0x3f00, 0
                ls                      dw      0x5142,0x0600
                pdn                     db      0x80
                cheads                  db      0
                sig                     db      0x29
                serialno        dw      0xce13, 0x4630
                label           db      'NO NAME'
                fattype         db      "FAT32"

_start:
                                                        ; set up the registers
                mov     ax, 0x07c0
                mov     ds, ax

Answer 2

There's nothing wrong with your bootloader, except this:

times 512-($-$$) db 0

Replace by:

times 510-($-$$) db 0

The way you are doing, your bootloader will be 514 bytes instead of 512. ;-)