format binary as 'img'
use16
org 7c00h
                cli
                mov     ax,0b800h
                mov     es,ax
                mov     ax,cs
                mov     ds,ax

                mov     dx,1f7h
            @@: in      al,dx
                and     al,0c0h                 ; Check disk to have no errors
                or      al,40h                  ; and ready
                jz      @b
                
                mov     al,0a0h                 ; Select master 0 head 0
                mov     dx,1f6h
                out     dx,al

                mov     al,1                    ; Read just one sector
                mov     dx,1f2h
                out     dx,al

                mov     al,2                    ; Starting at second
                mov     dx,1f3h
                out     dx,al

                mov     al,0                    ; Locate the head...
                mov     dx,1f4h
                out     dx,al

                mov     al,0                    ; ...at cylinder zero
                mov     dx,1f5h
                out     dx,al

                mov     al,20h                  ; Send read command
                mov     dx,1f7h
                out     dx,al

            @@: in      al,dx
                test    al,8                    ; Wait drive to gather data
                jz      @b

                cld
                mov     di,7c00h+512            ; Use adjacent boot load zone as buffer
                mov     cx,512/2
                mov     dx,1f0h
                rep     insw

                xor     di,di
                mov     ah,74h          
                mov     si,7c00h+512
            @@: mov     al,[si]
                or      al,al
                jz      @f
                mov     [es:di],ax              ; Show data on screen
                add     di,2
                inc     si
                jmp     @b

            @@: jmp     $


times 510-($-$$) db 0
                 dw 0aa55h
db 'This is the data to be loaded from RAM code. There is something hidden: ',0x53,0x45,0x43,0x52,0x45,0x54
times 2*1000000-($-$$) db 0
    

Code:

              mov     ax,cs
               mov     ds,ax    

xor ax,ax
mov ds,ax