{ **********************************************************************
  ** Program: S1DEB8.PAS             Version: 1.1- 16  February 1999  **
  ** Firm:      GRIFO(r)         Via  Dell'Artigiano 8/6              **
  **                          40016  San Giorgio di Piano (BO)        **
  **                          Tel. 051-892052  FAX  051-893661        **
  ** Developed by: Tassinari Enea                                     **
  **********************************************************************
  
  This program allows to display an incrementa counter on ports.
  In order to make an easier visualization of the status lines, it is 
  necessary to get a 20 pins flat cable for connecting GPC(r)15R CN9 connector
  to TIO 16 CN1 connector, or DEB-01 CN15 connector. }

program S1DEB8;
{$C-} { disable the Ctrl+C }

const
CNT=$17; { Control and command register of the PPI 82C55 }
PDA=$14; { Data register of the A port }
PDB=$15; { Data register of the B port }
PDC=$16; { Data register of the C port }
RIT=100; { Delay of 100 ms }

var
STATO:byte;
TASTO:char;
VAL:integer;
SWC:integer;
RIS:integer;

procedure INIZIALIZZAZIONE; 
{ Initialization of the control register of the 82C55 }
  begin 
   port[CNT]:=130;
  end;

function LETTURA (INDIRIZZO:integer):byte;
{ Read the B port }
 begin
   LETTURA:=port[INDIRIZZO];
 end; 


procedure SCRITTURA (STATO:integer);
{ Write on A and C Port }

var 
BYTEL,BYTEH:byte;  
  
 begin
   BYTEL:=STATO and $FF; 
   { Write into BYTEL variable only the low byte value of the contents of the 
     STATO variable }
   BYTEH:=(STATO and $FF00) shr 8; 
   { Write into BYTEH variable only the high byte value of the contents of the 
     STATO variable. The value came shift of 8 position in right direction so 
     you can see the BYTEH contents like low byte value. }                                         
   port[PDA]:=BYTEL;
   port[PDC]:=BYTEH;
  end;

begin {program main }
 clrscr;
 INIZIALIZZAZIONE;
 gotoxy(10,3);
 griteln('VISUALIZATION OF THE LED COUNTER ON A-C PORT IN PROGRESS');
 gotoxy(25,4); 
 write('Press any key for exit');
 gotoxy(14,6);
 write('Change the switch 1 position to inverte the counter');
   begin 
     SCRITTURA($FFFF); { Led of the A-C port in OFF }
     SWC:=LETTURA(PDB);
     RIS:=SWC and 1; { Sensibilize only the switch 1 of the dip switch }
     if RIS=0 then VAL:=1 
     { The switch 1 reading involve the lighting of the firs or last LED. } 
     else VAL:=$FFFF; 
        repeat
          begin
            SCRITTURA(VAL); 
            delay(RIT);
            SWC:=LETTURA(PDB);
            { Read the dip switch status }
            RIS:=SWC and 1;
            { Mask the switch }
             if RIS=0 then VAL:=VAL+1
             { You can do the positive counter or negative counter }
             else VAL:=VAL-1               
          end;
        until keypressed;
   end;  
 SCRITTURA($FFFF);
 { Led off in the end time }
 read(kbd,TASTO);
end.