; Flat Assembler uses the Intel syntax.
; Effective for: 
;      Flat assembler version 1.64 
;      emu8086 integrated assembler version 4.00-Beta-20 (or above)           

#fasm#   ; this code is for fasm. 

org 100h

name "fasmcomp"


; === [NOTE 1]  
; calculate the sum of 'a' and 'b' 

jmp start

a dw 5
b dw 7


start:

; this is correct syntax for emu8086 integrated assembler, 
; but it is wrong for fasm: 
mov ax, a
mov bx, b
add ax, bx    ; AX = offset a + offset b  (AX=206)   (correct, but not what we expect) 


; correct syntax for fasm: 
mov ax, [a]
mov bx, [b]
add ax, bx    ; AX = 5 + 7   (AX=000C)     (correct) 


;; to calculate sum of offsets for emu8086 integrated assembler 
;; it is required to use the offset directive, for example: 
;    mov ax, offset a 
;    mov bx, offset b 
;    add ax, bx    ; sum of offsets instead of values.              
;; the offset directive is not supported for fasm (error: extra characters on line) 


; Hello, World example in fasm:         
mov dx, msg
mov ah, 9
int 21h

; for emu8086 integrated assembler: 
;    mov dx, offset msg 
; or 
;    lea dx, msg 
; (syntax of the integrated 8086 assembler is mostly MASM/TASM compatible) 


; wait for any key... 
mov ah, 0
int 16h

ret

msg db "Hello, World!", 0x0D, 0x0A, "$"

; emu8086 compatible declaration is: 
; msg: db "Hello, World!", 0x0D, 0x0A, "$" 
;  (note: there is ":" after msg) 



; === [NOTE 2]   
; fasm does not support the comment directive, for example: 
; comment * 
;    la lalala la... 
; *       

; === [NOTE 3]      
; these precompiler directives are preparsed by the IDE: 
;  NAME 
;  #make... 
;  #AX=... 
;  etc... 


; === [NOTE 4]   
; for fasm it's required to use "byte" and "word" prefixes 
; in places where it may be required to use "byte ptr", "word ptr" 
; or "b.", "w." prefixes for the integrated 8086 assembler.  
; For example: 


mov byte [m1], AL
m1 dw 1234h

;	; for the integrated 8086 assembler it should be: 
;	mov b. m1, AL              
;	; or: 
;	mov byte ptr m1, AL  ; (MASM compatible) 


; === [NOTE 5]  
; uninitialised variables are not added to actual binary file 
; when these variables are located in the bottom of the file 
; and there is no defined data after them (MASM compatible) 
; 8086 assembler always initialises variables as 0 (MASM incompatibility) 
; For example: 

u1 dw ?


; === [NOTE 6]  
; fasm assembler is case sensitive; 
; for example, the following code would cause 
; "symbol redefinition" error for MASM or 8086 integrated assembler, 
; but it is completely legal for fasm: 

mov [d], 9
mov [D], 12
ret
d Dw 5
D dw 7

; === [NOTE 7]    
; there may be other slight syntax incompatibilities, 
; if you find any problem feel free to email.