Video            SEGMENT  AT 0400h

CmdReg       DB  ?
DataReg       DB  ?

Video            ENDS


Data              SEGMENT  Para Public  'Data'

Msg               DB  "etrov"

Data              ENDS


Code            SEGMENT  byte Public  'Code'
                      ASSUME cs:Code, ds:Data, es:Video

Start:            mov  ax, Video           ; initialize ES register
                     mov  es, ax
                     mov  ax, Data             ; initialize DS register
                     mov  ds, ax

; Initialize the Display Module,i.e. CLEAR_SCREEN
                     mov  cx, 0FFFFh
z1:                loop  z1                        ; wait
                     mov  CmdReg, 38h    ; Function Set

                     mov  cx, 0FFFFh    
z2:                loop  z2                        ; wait
                     mov  CmdReg, 0Fh    ; Set Display on/off control
   
                     mov  cx, 0FFFFh
z3:                loop  z3                        ; wait
                     mov  CmdReg, 01h    ; Clear Display

                     mov  cx, 0FFFFh
z4:                loop  z4                        ; wait
                     mov  CmdReg, 06h    ; Entry mode set
                     mov  cx, 0FFFFh
z5:                loop  z5                        ; wait
           
; Move cursor at row DH and column DL, i.e. MOVE_CURSOR
                     mov  dh, 0                    ; set the row
                     mov  dl, 0Ah                ; set the column
         
test1:           test  CmdReg, 80h      ; check if Display Module is ready
                     jnz  test1
                     test  dh, 0                     ; check if chosen row is 0
                     jnz  row1                       ; if no then row1
                     mov  bx, 80h
                     jmp  clm                        ; go to get the chosen column
row1:           mov  bx, 0C0h                ; if chosen row is 1 then set the right code
                     mov  bh, 0
clm:              add  bx, dx                   ; set up the addr of the cursor
                     mov  CmdReg, bl        ; send addr to Display Module
test2:            test CmdReg, 80h 
                      jnz  test2
                      
; Put the character from AL on the display,i.e. PUT_CHAR
                     mov  al, 'P'                    ;set the char
                     mov  DataReg, al         ; move the char to the Display Module
                     inc  bx                            ; inc to the next addr on the Display 
test3:           test  CmdReg, 80h       ; check if the Display Module is ready
                     jnz  test3

; Display the rest of the mane,i.e. PUT_ASCIIZ
                    mov  cx, 5                       ; initialize the loop counter  
                    mov  si, OFFSET Msg
                    mov  di, OFFSET DataReg
     
Rest:           test  CmdReg, 80h        ; check if Displey Module is ready
                    jnz  Rest
                    mov  CmdReg, bl           ; send addr to Display Module
test4:          test CmdReg, 80h
                    jnz  test4
                    movsb                              ; move the char to the Dispaly Module
                    dec  di                              ; reset di to point to DataReg
                    inc  bx                               ; inc to the next addr on the Display
                    loop Rest

Done:         jmp  Done                         ; infinite loop to keep message on Display

Code         ENDS
                   END  Start