'===========================================================================
' Subject: PROGRAM THE PARALLEL PORT          Date: 07-13-96 (13:44)       
'  Author: Christoph Kummetat                 Code: QB, QBasic, PDS        
'  Origin: FidoNet QUIK_BAS Echo            Packet: MISC.ABC
'===========================================================================
'> With 8 data lines I have many options and combinations thereof. I am
'> not familair with the bit structure of characters. Any clue as to how
'> to go about deciding the characters to use that would activate line
'> "1" only while leaving the others alone?

'here's some code, which might help you to program the parallel port. 
'Originally it is a programm to set 8 relais via LPT. I shortened it to the 
'important things. If you have more questions about, feel free to ask me...

InitVar:
   DEFINT A-Z
   DIM SHARED Bit(8), BitStatus, Port, RelNr
   DIM SHARED Anzahl(8)

   CONST Blk = 0, Blu = 1, Grn = 2, Zyn = 3, Red = 4  'set colors
   CONST Gry = 7, Yel = 14, Wht = 15, Blink = 16
   CONST TRUE = 1, FALSE = NOT TRUE                   'set boolean

   CLS : Count = 1
   FOR i = 1 TO 8
      Bit(i) = Count                                  'set bits with bit-values
      Count = Count + Count                           'increase values (0,1,2,4,8,16,32,64,128)
   NEXT i

   CALL DATEN.Find.LPT                                'search for LPTs

   BitStatus = 0                                      'switch all lines OFF
   OUT Port, BitStatus                                'send to LPT
   CALL DATEN.Get.Status                              'read LPT


WHILE INKEY$ <> "q"
   CALL DATEN.Set.Status
   FOR i = 1 TO 8
      CALL DATEN.Get.Status
   NEXT i
WEND

      OUT Port, LEDStatus                                      'an par. SN senden

SUB DATEN.Find.LPT
   DEF SEG = 0: DIM Port(4)
   Count = 0: COLOR Wht, Blu
   FOR i = 1032 TO 1036 STEP 2
      IF PEEK(i) + 256 * PEEK(i + 1) > 0 THEN
         Count = Count + 1
         Port(Count) = VAL("&H" + HEX$(PEEK(i) + 256 * PEEK(i + 1)))
         LOCATE 4 + Count, 6
         PRINT "Printerport"; STR$(Count); " : ";
         PRINT "&H" + HEX$(PEEK(i) + 256 * PEEK(i + 1))
      END IF
   NEXT i
   IF Count = 0 THEN                                          'no port found
      PRINT "No parallel port found on your PC !";
      ch$ = INPUT$(1)
      CLOSE : COLOR Wht, Blk: CLS : END
   END IF

GetPrt:                                                        'choose LPT
   LOCATE , 6: PRINT "Which parallel port do you want to use : ";
   v$ = INPUT$(1)                                              'ask for LPT
   IF VAL(v$) < 1 OR VAL(v$) > Count THEN
      SOUND 3200, .3: GOTO GetPrt                              'invalid value
   END IF
   Port = Port(VAL(v$))                                        'define port
END SUB

SUB DATEN.Get.Status
     BitStatus = INP(Port)                                     'read LPT
     FOR i = 1 TO 8
         IF BitStatus AND Bit(i) THEN
            Status = 1
         ELSE
            Status = 0
         END IF
     CALL DISPLAY.Status(i, Status)
     NEXT i
END SUB

SUB DATEN.Relais.Reset
     BitStatus = 0: OUT Port, BitStatus                        'reset all registers at LPT
END SUB

SUB DATEN.Set.Status                                           'send value to LPT
   COLOR Blk, Gry:
   LOCATE 12, 6: PRINT "which line to set ? : "
   LOCATE 13, 6: PRINT "(number 1 - 8 or 0 for all OUT)  "

GetBit:
   v$ = INPUT$(1)                                              'number of LPT
   BitNr = VAL(v$)
   IF ASC(v$) = 27 THEN COLOR Wht, Blk: CLS : END              'Escape, end program
   IF BitNr > 8 THEN SOUND 3200, .3: GOTO GetBit               'hey, you can only choose between 1 and 8
GetSts:
   IF BitNr = 0 THEN
      BitStatus = 0                                            'switch all lines OFF
      OUT Port, BitStatus                                      'send to LPT
      CALL DISPLAY.Status(BitNr, BitStatus)                    'display status
   ELSEIF BitStatus AND Bit(BitNr) THEN                        'is line ON or OFF ?
      BitStatus = BitStatus XOR Bit(BitNr)                     'swith bit/line to OFF
      OUT Port, BitStatus                                      'send to LPT
      CALL DISPLAY.Status(BitNr, BitStatus)                    'display status
   ELSE
      BitStatus = BitStatus + Bit(BitNr)                       'add bit/line
      OUT Port, BitStatus                                      'send to LPT
      CALL DISPLAY.Status(BitNr, BitStatus)                    'display status
   END IF
END SUB

SUB DISPLAY.Status (BitNr, Status)                             'show status of bits/lines
   IF BitNr >= 1 THEN
      IF Status >= 1 THEN
         COLOR Wht, Red                                        'bit/line active
         LOCATE 8, ((BitNr * 8) + BitNr) - 3: PRINT "  ON  "
       ELSE
         COLOR Wht, Grn                                        'bit/line inactive
          LOCATE 8, ((BitNr * 8) + BitNr) - 3: PRINT " OFF  "
      END IF
   ELSE
      COLOR Wht, Grn                                           'all bits/lines OFF
         FOR i = 1 TO 8
         LOCATE 8, ((i * 8) + i) - 3: PRINT " OFF  "
      NEXT i
   END IF
END SUB