Fixed it. That code is fine, its just that since I don't have a debugger I couldn't see if it read it or not. The part of that code that is supposed to display the read bytes is not working though, but I can live without it.

My problem is solved then.

Don't really know what is wrong, but I do know (you might too if you have the emu8086 debugger) that the last letter is 42H (B in ASCII) and it is adding 1DH to it because the previous conditional statements does not fulfill. As you might know in hex 42 + 1D = 5F and 5F is an ASCII underscore (_).

What I did was to change letter B for a "y" manually. I don't know if all "B"s will always be "y", but if not, I wouldn't know what to do since I don't really understand Caesar Cipher.

Add this in between:
cmp al, ' '
je display2

;Add here

cmp al, 7Ah
jge wrap

cmp al, 'B'
jne noBletter
mov al, 79h
jmp display2
noBletter:

Final code would be:

org 100h

mov cl, 28
mov ah, 0eh
lea si, d1
loop1:
mov al, [si]
inc si
je display1
cmp al, ' '
je display1
display1:
int 10h
loop loop1

mov dh, 2
mov dl, 0
mov bh, 0
mov ah, 2
int 10h

mov cl, 28
mov ah, 0eh
lea si, d1
loop2:
mov al, [si]
inc si
cmp al, 'C'
je display2
cmp al, ' '
je display2
cmp al, 'B'
jne noBletter
mov al, 79h
jmp display2
noBletter:
cmp al, 7Ah
jge wrap
add al, 1dh
jmp display2
wrap:
add al, 37h
display2:
mov ah, 0eh
int 10h
loop loop2

ret

d1 db 'PHHW PH DIWHU WKH WRJD SDUWB'

no2pencil, on 03 April 2012 - 05:46 PM, said:

Ah, now that you mention it, I've always been writing it to a flash drive with an hex editor and booting from the flash drive. I wanted to test it before writing it to the hard disk, but yeah, maybe writing it to the hard disk MBR will make it work. I'll try that. I have already made an application in C++ to backup my current MBR so I don't worry about screwing anything.

GunnerInc, on 03 April 2012 - 05:47 PM, said:

Never read any of that, but now I have read a little of it. Though, I only get a minimal amount of it, there are lots of concepts I'm not familiarized with. I might find something if I keep reading.

This thread wasn't to ask about the code I have, but I'll leave the last one I tried without success for if anyone can spot what I'm doing wrong.

#make_boot#

org 7c00h      ; set location counter.

jmp 0x0000:start     ;
        
start:
buff DW 512
MOV ES,AX
MOV BX,offset buff


;Parameters that will be passed to interrupt 13 to read the hard disk
MOV AH,1     ;Read Sectors
MOV AL,1     ;Sectors To Read Count
MOV CH,0     ;Track 0
MOV CL,0     ;Sector 0
MOV DH,0     ;Head 0
MOV DL,80h   ;1st hard disk
int 13h      ;call interrupt

      
;Procedure to display the read bytes
LEA SI, buff  ; Load bytes into SI to display them
MOV AH, 0Eh   ;teletype function identifier

Print:
MOV AL, [SI]
CMP AL, 0     ;Check if we have reached the end of our message 
JZ Done       ;If the CMP operation before yielded a flag of 0, jump to 'Done', else continue below.
INT 10h       ;print character stored in AL
INC SI        ;To read what is contained in the next position of SI
JMP Print



Done:
MOV AH, 0     ;'Wait for any key press' identifier of INT 16H
INT 16H

MOV AX, 0040h ;Store address to which we will pass a value later to do a cold boot
MOV DS, AX    ;Move to Data Segment the address value
MOV w.[0072h], 0000h ;Store in the segment 0072h of 0040h address the value of 0000h
JMP 0FFFFh:0000h ;Move to that address which contains the data that will reboot the system