Using a PC's parallel port for more than printers... with old systems and software

PLEASE NOTE: You CAN damage your computer if you make ill-advised connections to it.
Any use you make of anything you find here must be AT YOUR OWN RISK

Here you will find information about......

• How to send and receive data to/ from the parallel port.
  
• Help on the software issues, with Basic, Pascal and Delphi addressed.
• and a way to email me, for whatever I've missed!

Software...

For a simple program to turn bits on or off just by clicking a button, go to my shareware site. There are free programs there... some for toggling or reading bits, including one for electronic time measurement via the parallel port, or via a joystick's "fire" buttons. There are some for Windows 98, which may even work on earlier systems, in addition to versions for later systems.

To send 123 to the parallel port....

    port[888]:=123;

    procedure PortOut(IOport:word; Value:byte); assembler;
    asm
      xchg ax,dx
      out dx,al
    end;

   PortOut(888,123);

    Out &h378,123

Hardware

Bit Pin Name
3   15   Error
4   13   Select In
5   12   Paper Empty
6   10   Acknowledge
7   11   Busy

Bit Pin Name
0    1   Strobe
1   14   Auto Linefeed
2   16   Initialize
3   17   Select Out

The rest of this page is rough.... but ready.

procedure TForm1.FormCreate(Sender: TObject);
begin
  (*initialize*)
   button1.caption:='255';
   port[888]:=255;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
if button1.caption='255' then begin
      button1.caption:='0';
      port[888]:=0;
      (*Makes outputs 0v*)
     end(*no ; here*)
  else begin
      button1.caption:='255';
      port[888]:=255;
      (*Makes outputs 5v*)
      end;
end;

implementation

{$R *.DFM}
{$R+} {nothing to do with previous $R}

(*The Delphi 2 on-line help has an entry for Mem[<seg>:<offset>], but
  the compiler does not seem to recognize it, not does it appear in the
  Reference Library Guide. Various postings in usergroups
  seem to say that Win95 will not let programs access physical memory.
  There was also an entry for something called ExtEscape which looked
  promising for sending something to the port, but I haven't explored
  that yet, and it didn't appear in Reference Library Guide either.

 Peter Below (TeamB) provided the following port access routines
 in a newsgroup post. He said push and pop were not needed, that
 they were in fact bad ideas. He pointed out that the function uses
 the normal Delphi 2/3 register calling convention and thus will get
 the first parameter (e.g. IOPort) in eax, the second in edx.

 In addition, he said...
 This will not work on NT; it works on Win9x only because the OS has a
 generic port driver. For NT you need to install such a driver first.
 Here are a few URLs worth checking:
    TVicHW32       http://www.entechtaiwan.com/tools.htm
    DriverX        Tinyport (NT only)

    procedure PortOut(IOport:word; Value:byte); assembler;
    asm
      xchg ax,dx
      out dx,al
    end;

(*More, similar, routines from Peter Blow. They are not needed
  in this simple demo program...

    function PortIn(IOport:word):byte; assembler;
    asm
      mov dx,ax
      in al,dx
    end;

    function PortInW(IOport:word):word; assembler;
    asm
      mov dx,ax
      in ax,dx
    end;

    procedure PortOutW(IOport:word; Value:word); assembler;
    asm
      xchg ax,dx
      out dx,ax
    end;

End of material from Peter Blow*)

procedure TForm1.Timer1Timer(Sender: TObject);
begin
if bPoke<>0 then begin
   Label1.caption:='0';
   bPoke:=0;
   PortOut(888,bPoke);
 end(*no ; here*)
 else begin
   Label1.caption:='255';
   bPoke:=255;
   PortOut(888,bPoke);
 end;(*else*)
end;

end.

Name: TDLPortIO 1.3 Date: 12/7/99
Environment: Delphi 3.0, Delphi 4.0, C++ Builder 3.0, C++ Builder 4.0 Download
Type: Freeware with Source Size: 851 Kb
Description:
TDLPortIO is a wrapper for the free DriverLINX kernel mode driver (included).
It allows full port IO under Windows 95/98/NT.
Comes with a C++ Builder and Delphi components,
ActiveX control (for Visual BASIC) and DLL version.
Compatible with the shareware package TVicPort.

Haven't found what you wanted? Click here to go to a further page consisting mainly of links to other resources.

Ad from page's editor: Yes.. I do enjoy compiling these things for you... hope they are helpful. However.. this doesn't pay my bills!!! If you find this stuff useful, (and you run an MS-DOS or Windows PC) please visit my freeware and shareware page, download something, and circulate it for me? At least (please) send an 'I liked the parallel port use page, and I'm from (country / state)' email? (No... I don't do spam) Links on your page to this page would also be appreciated!

Don't forget to check out the programs for writing to or reading from the parallel port at my freeware and shareware site. All of the software is only for Windows, I fear. Most of my software will run on anything from Windows 3.1 to Vista and probably beyond... but the ones that interact with ports tend to be restricted to "before NT (pr XP)" and "after Win98" because of OS issues determined in Redmond.

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