Uses Crt, Dos;


Const
  BaseAddress : Word = $350;
  IRQ = 5;

Var
  IDIntVec : Procedure;
  IntOccurred : Boolean;
  Key : Char;
  LoopVar : Byte;
  ValueRead, ValueMask : Word;

Function Deci(DS : String) : Word;
Var
 BS : String;
 Er : Integer;
 DI : Word;
Begin
 BS := '$' + DS;
 Val(BS, DI, Er);
 Deci := DI;
End;

Function Hex(BB : Word) : String;
Var
 AA, CC : Byte;
 DD : String;
 HexTable : String;
Begin
 HexTable := '0123456789ABCDEF';
 DD := '000';
 DD[3] := HexTable[(BB AND $00F) + 1];
 DD[2] := HexTable[((BB AND $0F0) SHR 4) + 1];
 DD[1] := HexTable[((BB AND $F00) SHR 8) + 1];
 Hex := DD;
End;

Procedure ExitProgram(errorCode : Integer);
Begin
  ClrScr;
  WriteLn('A fatal error occured, program halted!');
  WriteLn('Error code returned was ', errorCode);
End;

function AskForBaseAddress(OldOne : String) : Word;
const
   Msg : string[4] = '0';
var
   NewOne, Success, Dummy, Error : Word;
   AddrInputPosX, AddrInputPosY : Word;
begin
   if (OldOne = 'OLD') then OldOne := Msg;
   WriteLn('Please enter the Base Address (0000-FFFF) for your card (in hex)');
   WriteLn('or press ENTER for ', OldOne, '.  ');
   Write('>');
   AddrInputPosX := WhereX; AddrInputPosY := WhereY;
   repeat
      GotoXY(AddrInputPosX, AddrInputPosY);
      ClrEol;
      Readln(Msg);
      Val('$' + Msg, NewOne, Error);
      if (error=0) then begin
         Success := 1;
         Dummy := NewOne;
      end else if (Msg = '') then begin
         GotoXY(AddrInputPosX, AddrInputPosY);
         WriteLn(OldOne);
         Msg := OldOne;
         Success := 1;
         Val('$' + Msg, Dummy, Error);
      end;
   until (Success = 1);
   AskForBaseAddress := Dummy;
end;  { end of AskForBaseAddress }

Procedure EnableMicroprocessor;
Begin
   Port[BaseAddress + 5] := 0;
End;

Procedure DisableMicroprocessor;
Var
  Hold : Byte;
Begin
   Hold := Port[BaseAddress + 1];
End;

{$F+}
Procedure IDIInterrupt; interrupt;
Begin
  IntOccurred := True;
  Port[$20] := $20;
End;
{$F-}


Begin

  ClrScr;
  BaseAddress := AskForBaseAddress('350');     { Prompt for base addr }
  WriteLn('Pascal Language Sample for IDI-48 Option C.  Version 1.00');
  WriteLn;
  WriteLn;
  WriteLn('This sample will show option C''s functionality.');
  WriteLn;
  WriteLn('IDI-48 Card setup:');
  WriteLn('  Card is at base address ', Hex(BaseAddress), ' Hex.');
  WriteLn('  Card is set at IRQ5.');
  WriteLn('  MODE switch has switch 1 OFF and 2-5 ON.');
  WriteLn;
  WriteLn('Press any key to continue...                                    ');
  WriteLn;
  Key := ReadKey;

  Port[$21] := Port[$21] AND NOT(1 SHL IRQ); { Enable IRQ5 on motherboard }
  Port[$20] := $20;                          { Clear interrupts }
  GetIntVec(IRQ + 8, @IDIntVec);             { Save old interrupt routine }
  SetIntVec(IRQ + 8, Addr(IDIInterrupt));    { Set to new interrupt routine }

  EnableMicroprocessor;

  ClrScr;

  Repeat

     GotoXY(1, 1);
     WriteLn('Toggle a bit on digital port 0.  The microprocessor will');
     WriteLn('detect a change of state and generate an interrupt on');
     WriteLn('IRQ5.  Press ESC to exit the program.');

     Repeat Until (IntOccurred OR KeyPressed);

     If NOT IntOccurred Then                            { If no interrupt }
       Begin                                            { check for exit }
         Key := ReadKey;
         If Key = #27 Then                              { If exit then. . . }
           Begin
             ClrScr;
             WriteLn('Exiting Sample 0 Program...');    { notify and. . . }
             Port[$21] := Port[$21] OR (1 SHL IRQ);     { Disable IRQ5 }
             SetIntVec(IRQ+8,Addr(IDIntVec));           { Restore ISR }
             DisableMicroprocessor;                     { Disable processor }
             Exit;                                      { Exit }
           End;
       End

     Else

       Begin                                            { If one did occur }
          Sound(500);
          Delay(100);
          Nosound;
          GotoXY(1, 5);
          WriteLn('A bit of data port zero was toggled!');
          WriteLn('It is now: ');
          ValueRead := PortW[BaseAddress];
          For LoopVar := 0 To 15 Do
            Begin
               ValueMask := 1 SHL LoopVar;
               WriteLn('  Bit ', LoopVar, ' = ',
                       Ord((ValueRead AND ValueMask) = ValueMask));
            End;
          WriteLn;
          IntOccurred := False;
          EnableMicroprocessor;
       End;

  Until KeyPressed;

End.