banyak teknik/format boleh digunakan dalam flat assembler..
ini kerana fasm amat fleksibel dan mempunyai sistem macro yg powerful
untuk newbie, terdapat 2 teknik yg sesuai, iaitu

;hello.asm
; example of simplified Win32 programming using complex macro features

include '%fasminc%/win32ax.inc'

.code

  start:
    invoke  MessageBox,HWND_DESKTOP,"Hi! I'm the example program!","Win32 Assembly",MB_OK
    invoke  ExitProcess,0

.end start


;hello2.asm
; lebih fleksibel

format PE GUI 4.0
entry start                     ; entry point at label start:

include '%fasminc%/win32a.inc'


section '.text' code readable executable
  start:
        invoke  MessageBox,HWND_DESKTOP, Mesej, Tajuk, MB_OK
        invoke  ExitProcess,0


section '.data' data readable writeable

  Mesej db "Hi! I'm the example program!"
  Tajuk db "Win32 Assembly"

section '.idata' import data readable

  library kernel,'KERNEL32.DLL',\
          user,'USER32.DLL'

  import kernel,\
         ExitProcess,'ExitProcess'

  import user,\
         MessageBox,'MessageBoxA'  



; example of simplified Win32 programming using complex macro features

include '%fasminc%\win32ax.inc'

section '.data' data readable writeable

  mainhwnd dd ?
  hinstance dd ?
  _title db 'Win32 program template',0
  _class db 'FASMWIN32',0

  msg MSG
  wc WNDCLASS

.code

  mula:
        invoke  GetModuleHandle,0
        mov     [hinstance],eax
        invoke  LoadIcon,0,IDI_APPLICATION
        mov     [wc.hIcon],eax
        invoke  LoadCursor,0,IDC_ARROW
        mov     [wc.hCursor],eax
        mov     [wc.style],0
        mov     [wc.lpfnWndProc],WindowProc
        mov     [wc.cbClsExtra],0
        mov     [wc.cbWndExtra],0
        mov     eax,[hinstance]
        mov     [wc.hInstance],eax
        mov     [wc.hbrBackground],COLOR_BTNFACE+1
        mov     [wc.lpszMenuName],0
        mov     [wc.lpszClassName],_class
        invoke  RegisterClass,wc

        invoke  CreateWindowEx,0,_class,_title,WS_VISIBLE+WS_DLGFRAME+WS_SYSMENU,128,128,192,192,NULL,NULL,[hinstance],NULL
        mov     [mainhwnd],eax

  msg_loop:
        invoke  GetMessage,msg,NULL,0,0
        or      eax,eax
        jz      end_loop
        invoke  TranslateMessage,msg
        invoke  DispatchMessage,msg
        jmp     msg_loop

  end_loop:
        invoke  ExitProcess,[msg.wParam]

proc WindowProc, hwnd,wmsg,wparam,lparam
        push    ebx esi edi
        cmp     [wmsg],WM_DESTROY
        je      wmdestroy
  defwndproc:
        invoke  DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
        jmp     finish
  wmdestroy:
        invoke  PostQuitMessage,0
        xor     eax,eax
  finish:
        pop     edi esi ebx
        return
 endp

.end mula


; template for program using standard Win32 headers

format PE GUI 4.0
entry start

include '%fasminc%\win32a.inc'

section '.data' data readable writeable

  _title db 'Win32 program template',0
  _class db 'FASMWIN32',0

  mainhwnd dd ?
  hinstance dd ?

  msg MSG
  wc WNDCLASS

section '.code' code readable executable

  start:
        invoke  GetModuleHandle,0
        mov     [hinstance],eax
        invoke  LoadIcon,0,IDI_APPLICATION
        mov     [wc.hIcon],eax
        invoke  LoadCursor,0,IDC_ARROW
        mov     [wc.hCursor],eax
        mov     [wc.style],0
        mov     [wc.lpfnWndProc],WindowProc
        mov     [wc.cbClsExtra],0
        mov     [wc.cbWndExtra],0
        mov     eax,[hinstance]
        mov     [wc.hInstance],eax
        mov     [wc.hbrBackground],COLOR_BTNFACE+1
        mov     [wc.lpszMenuName],0
        mov     [wc.lpszClassName],_class
        invoke  RegisterClass,wc

        invoke  CreateWindowEx,0,_class,_title,WS_VISIBLE+WS_DLGFRAME+WS_SYSMENU,128,128,192,192,NULL,NULL,[hinstance],NULL
        mov     [mainhwnd],eax

  msg_loop:
        invoke  GetMessage,msg,NULL,0,0
        or      eax,eax
        jz      end_loop
        invoke  TranslateMessage,msg
        invoke  DispatchMessage,msg
        jmp     msg_loop

  end_loop:
        invoke  ExitProcess,[msg.wParam]

proc WindowProc, hwnd,wmsg,wparam,lparam
        push    ebx esi edi
        cmp     [wmsg],WM_DESTROY
        je      wmdestroy
  defwndproc:
        invoke  DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
        jmp     finish
  wmdestroy:
        invoke  PostQuitMessage,0
        xor     eax,eax
  finish:
        pop     edi esi ebx
        return
endp

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          user,'USER32.DLL'

  import kernel,\
         GetModuleHandle,'GetModuleHandleA',\
         ExitProcess,'ExitProcess'

  import user,\
         RegisterClass,'RegisterClassA',\
         CreateWindowEx,'CreateWindowExA',\
         DefWindowProc,'DefWindowProcA',\
         GetMessage,'GetMessageA',\
         TranslateMessage,'TranslateMessage',\
         DispatchMessage,'DispatchMessageA',\
         LoadCursor,'LoadCursorA',\
         LoadIcon,'LoadIconA',\
         PostQuitMessage,'PostQuitMessage'