8255 interfacing with 8086 DAC

Problem Statement: 8255
Write 8086 ALP to interface DAC and generate following waveforms on oscilloscope,

(i) Square wave - Variable Duty Cycle and Frequency.
(ii) Ramp wave - Variable direction
(iii) Trapezoidal wave 
(iv) Stair case wave

----------------------------Square wave--------------------------

0000:4000 MOV CL,FF

0000:4002  DEC CL

0000:4004  JNZ 4002

0000:4006 RET

0000:4007  MOV AL, 80

0000:4009  OUT 67, AL

0000:400B  MOV AL, 01

0000:400D  OUT 63, AL

0000:400F  MOV AL, 00

0000:4011  OUT 61, AL

0000:4013  CALL 4000

0000:4016  MOV AL, FF

0000:4018  OUT 61, AL

0000:401A  CALL 4000

0000:401D  JMP 400F

0000:401F  INT 3     

----------------------------Staircase wave-----------------------

0000:2050  MOV AL, 80
0000:2052  OUT 67, AL
0000:2054  MOV AL, 01
0000:2056  OUT 63, AL
0000:2058  MOV AL, 00
0000:205A  OUT 61, AL
0000:205C  CALL 1000
0000:205F  MOV AL, 55
0000:2061  OUT 61, AL
0000:2063  CALL 1000
0000:2066  MOV AL, AA
0000:2068  OUT 61, AL
0000:206A  CALL 1000
0000:206D  MOV AL, FF
0000:206F  OUT 61, AL
0000:2071  CALL 1000
0000:2074  MOV AL, AA
0000:2076  OUT 61, AL
0000:2078  CALL 1000
0000:207B  MOV AL, 55
0000:207D  OUT 61, AL
0000:207F  CALL 1000
0000:2082  MOV AL, 00
0000:2084  JMP 205A
0000:2086  INT 3    

----------------------------Square tooth wave--------------------

0000:5000  MOV AL,80
0000:5002  OUT 67,AL
0000:5004  MOV AL,01
0000:5006  OUT 63,AL
0000:5008  MOV AL,00
0000:500A  OUT 61,AL
0000:500C  INC AL
0000:500E  OUT 61,AL
0000:5010  CMP AL,FF
0000:5012  JNZ 500C
0000:5014  JMP 5008
0000:5016  INT 3                  

  

----------------------------Saw tooth wave----------------------

0000:6000  MOV AL,80
0000:6002  OUT 67,AL
0000:6004  MOV AL,01
0000:6006  OUT 63,AL
0000:6008  MOV AL,FF
0000:600A  OUT 61,AL
0000:600C  DEC AL
0000:600E  OUT 61,AL
0000:6010  CMP AL,00
0000:6012  JNZ 600C
0000:6014  JMP 6008
0000:6016  INT 3  

  

----------------------------Triangular wave----------------------

0000:7000  MOV AL, 80
0000:7002  OUT 67, AL
0000:7004  MOV AL, 01
0000:7006  OUT 63, AL
0000:7008  MOV AL, 00
0000:700A  OUT 61, AL
0000:700C  INC AL
0000:700E  OUT 61, AL
0000:7010  CMP AL, FF                                            
0000:7012  JNZ 700C
0000:7014  DEC AL
0000:7016  OUT 61, AL
0000:7018  CMP AL, 00
0000:701A  JNZ 7014
0000:701C  JMP 7008
0000:701E  INT 3