Parallel Port I/O Using Delphi V 6.0

(With thanks to Ken Hopkins for the techniques ...)

NOTE: Delphi 6 Personal may be downloaded from: http://www.borland.com/delphi/tryitnow.html 

STEP 1    Copy Fred Bulback's io.dll into the default Project Folder.   
 See: http://geekhideout.com/downloads/io.dll

STEP 2    Create a Form with eight buttons for the Output Lines (D0 to D7), one button to turn all lines off, one button to read Input and a Label to display the value read at the Input lines.

STEP 3    Insert the following lines of code into the Unit script...

procedure PortOut(Port : Word; Data : Byte); stdcall; external 'io.dll';
function PortIn(Port:Word):Byte; stdcall; external 'io.dll';

STEP  4    Enter code for each of the Output buttons as below ...

procedure TForm1.Button1Click(Sender: TObject);
begin
   PortOut(888,1);
end;

STEP 5     Enter code for the Input button as below ...   

procedure TForm1.Button3Click(Sender: TObject);
var
   InValue : Byte;
begin
   InValue := PortIn(889);
   label1.Caption := IntToStr(InValue); { Converts InValue from Type Byte to Type String.}
end;

The full code is here if you want to download it.

NOTE: On some systems the addresses are: 956 and 957 rather than 888 and 889.

STEP 6     Attach an interface, or launch Fred Bulback's "parmon.exe" and Run your program ...