{ sample2.pas   ...for the PIOD24, compile with TP7 }


Uses

  Strings, crt;

Const

  True = 1;
  False = 0;

var

  TempX, TempY: byte;


function AskForBaseAddress(OldOne : String) : integer;
const
   Msg : string[3] = '0';
var
   NewOne, Success, Dummy, Error : Word;
   AddrInputPosX, AddrInputPosY : Word;
begin
   if (OldOne = 'OLD') then OldOne := Msg;
   AddrInputPosX := WhereX; AddrInputPosY := WhereY;
   Success := 0;
   repeat
      GotoXY(AddrInputPosX, AddrInputPosY);
      ClrEol;
      Readln(Msg);
      Val('$' + Msg, NewOne, Error);
      if ((NewOne <= $3F8) AND (NewOne >= $100)) then begin
         Success := 1;
         Dummy := NewOne;
      end else if (Msg = '') then begin
         GotoXY(AddrInputPosX, AddrInputPosY);
         WriteLn(OldOne);
         Msg := OldOne;
         Success := 1;
         Val('$' + Msg, Dummy, Error);
      end else begin
        GotoXY( TempX, TempY); clreol;
        WriteLn(
          'range error, please type a number between 100 and 3f8');
      end;
   until (Success = 1);
   AskForBaseAddress := Dummy;
end;


var

  PromptSpaceX: byte;
  PromptSpaceY: byte;
  IntPromptX: byte;
  IntPromptY: byte;

  Register8, index: byte;
  BaseAddr, done: integer;
  ch: char;

begin
  ClrScr;
  Writeln( 'PIOD24 SAMPLE TWO');
  Writeln( '');
  WriteLn( 'This program initializes the PIOD24 control register at offset 8');
  Writeln( 'note: the client driver for this device must be installed first');
  Writeln( '');
  Writeln( '----------------------------------------------------------------');
  WriteLn( '');

  Register8 := 0;
  PromptSpaceX := WhereX;                   { redundant }
  PromptSpaceY := WhereY;                   { redundant }
  TempX := WhereX; TempY := WhereY;
  WriteLn( 'what is the board''s base I/O address in hex?');
  BaseAddr := AskForBaseAddress( '300');

  repeat
    index := PromptSpaceY;
    repeat
      GotoXY( 1, index); clreol; Inc( index);   { clear lines below the msg }
    until index = 25;
    GotoXY( PromptSpaceX, PromptSpaceY);
    WriteLn( 'press I for interrupt selection');
    WriteLn( 'press C for clock source selection');
    WriteLn( 'press L for counter link selection');
    WriteLn( 'press E to exit');
    ch := ReadKey;
    case ch of
      'i', 'I':
      begin
        { display the user's choice }
        WriteLn( 'Interrupt Selection (press a number key)');
        WriteLn( '');
        { prompt the user for the interrupt source }
        WriteLn( '0 No interrupt');
        WriteLn( '1 External');
        WriteLn( '2 8255 PC0 (digital I/O)');
        WriteLn( '3 Counter 0');
        WriteLn( '4 Counter 1');
        WriteLn( '5 Counter 2');
        WriteLn( '6 8255 PC3 (digital I/O)');
        ch := ReadKey;
        if (ch < '0') or (ch > '6') then                { range check }
        begin
          WriteLn( 'interrupt selection error, press a key to continue');
          ReadKey;
          gotoxy( 1, PromptSpaceY);
        end
        else
        begin
          { change bits 5, 6, and 7 of the interrupt control register }
          Register8 := Register8 and $1f;
          Register8 := Register8 or ((byte(ch) - $30) shl 5);
          port[ BaseAddr + 8] := Register8;
          WriteLn( '');
          Write( 'press a key to continue'); { hold the display }
          ReadKey;
        end;
      end;

      'c', 'C':
      begin
        { display the user's choice }
        WriteLn( '');
        WriteLn( 'Clock Source Selection (press a number key):');
        { prompt the user for the counter to be programmed }
        WriteLn( '0 Counter 0 source = 10MHz');
        WriteLn( '1 Counter 0 source = external clock 0');
        WriteLn( '2 Counter 1 source = 10MHz');
        WriteLn( '3 Counter 1 source = 1MHz');
        WriteLn( '4 Counter 2 source = 1MHz');
        WriteLn( '5 Counter 2 source = external clock 1');
        ch := Readkey;
        if (ch < '0') or (ch > '5') then        { range check }
        begin
          { on error clear the data input section of the screen }
          WriteLn( 'Clock source selection error, press a key to continue');
          ReadKey;
          GotoXY( 1, PromptSpaceY);
        end
        else    { change bits 2, 3, and 4 }
        begin
          case ch of
            '0': Register8 := Register8 and $fb; { clear bit 2 }
            '1': Register8 := Register8 or 4;    { set bit 2 }
            '2': Register8 := Register8 and $f7; { clear bit 3 }
            '3': Register8 := Register8 or 8;    { set bit 3 }
            '4': Register8 := Register8 and $ef; { clear bit 4 }
            '5': Register8 := Register8 or $10;  { set bit 4 }
          end;
          port[ BaseAddr + 8] := Register8;
          { clear the data input section of the screen }
          WriteLn( '');
          WriteLn( 'press a key to continue'); { hold the display }
          ReadKey;
        end;
      end;

      'l', 'L':
      begin
        { display the user's choice }
        WriteLn( 'Counter Link Selection (press a number key):');
        { prompt the user for the counter to be programmed }
        WriteLn( '0 no links');
        WriteLn( '1 Counters 1 and 2 linked');
        WriteLn( '2 Counters 0 and 1 and 2 linked');
        ch := ReadKey;
        if (ch < '0') or (ch > '2') then   { range check }
        begin
          { on error clear the data input section of the screen }
          WriteLn( 'Counter link selection error, press a key to continue');
          ReadKey;
          GotoXY( 1, PromptSpaceY);
        end
        else    { modify bits 0 and 1 of the interrupt control reg }
        begin
          Register8 := Register8 and $fc;  { clear bits 0 and 1 }
          case ch of
            '1': inc( Register8);
            '2': inc( Register8, 2);
          end;
          port[ BaseAddr + 8] := Register8;
          WriteLn( 'press a key to continue');  { hold the display }
          ReadKey;
        end;
      end;

      'e', 'E': done := TRUE;

    end;
  until done = TRUE;

end.