tablero

format binary as 'img'
ORG 7C00h

  MOV AX, 13h
  INT 10h

  MOV AX, 0xA000
  MOV ES, AX

  CALL bg_draw

  JMP $

  bg_draw:
    MOV CX, 64000
    MOV DI, 0
    MOV AL, [verde]

    bg_draw_loop:
      MOV [ES:DI], AL
      INC DI
    LOOP bg_draw_loop

    CALL tablero
    RET

  tablero:
    MOV CX, 5
    cuadrado_filas_loop:
      XOR AX, AX
      MOV AL, [blanco]
      PUSH CX
      MOV CX, 4
      cuadrado_loop:
        PUSH CX
        MOV DI, [aux]
        CALL cuadrado
        POP CX
        MOV BX, [offset_x]
        ADD [aux], BX
      LOOP cuadrado_loop

      ADD [row], 1

      MOV AX, [offset_y]
      MOV BX, [row]
      MUL BX

      MOV BX, 320
      MUL BX
      MOV [aux], AX

      MOV AX, [row]
      AND AX, 00000001b
      JZ par

      impar:
        ADD [aux], 40

      par:

      POP CX
    LOOP cuadrado_filas_loop
    RET

  cuadrado:
    MOV CX, [n]

    pintar_filas:
      PUSH CX

      MOV CX, [n]
      pintar_cols:
        MOV [ES:DI], AL
        INC DI
      LOOP pintar_cols
      ADD DI, 320-40
      POP CX
    LOOP pintar_filas
  RET

blanco db 00001111b
negro db 00000000b
verde db 00000010b
n dw 40
offset_x dw 80
offset_y dw 40
aux dw 0
row dw 0

times 510-($-$$) db 0
  dw 0xAA55