POMOČ: C# Spremenitev spremenljivke medtem ko teče ukaz while

Delam progrm za upravljanje led diodad priklopljenih na LPT(printer) port.
Nastavil sem kako naj se led diode prižigajo in vmes dodal 100ms intervale.
Naredil sem da se ponavlja vendar je problem v tem da se program(forma) neha odzivati in tako ne morem spremeniti spremenljivke a na vrednost 1, da bi se zanka ustavila.
Prosim za pomoč.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections;
using System.Threading;
using System.Timers;

namespace TEST
{
public partial class Form1 : Form
{
int a = 0;
public Form1()
{
InitializeComponent();
PortAccess.Output(888, 0);
}
//reset
private void button1_Click(object sender, EventArgs e)
{
a = 1;
PortAccess.Output(888, 0);
}
//set
private void button2_Click(object sender, EventArgs e)
{
PortAccess.Output(888, 255);
}
//rider
private void button3_Click(object sender, EventArgs e)
{
a = 0;
while (a == 0)
{
PortAccess.Output(888, 4);
Thread.Sleep(100);

PortAccess.Output(888, 10);
Thread.Sleep(100);

PortAccess.Output(888, 17);
Thread.Sleep(100);

PortAccess.Output(888, 27);
Thread.Sleep(100);

PortAccess.Output(888, 31);
Thread.Sleep(100);

PortAccess.Output(888, 30);
Thread.Sleep(100);

PortAccess.Output(888, 28);
Thread.Sleep(100);

PortAccess.Output(888, 24);
Thread.Sleep(100);

PortAccess.Output(888, 16);
Thread.Sleep(100);

PortAccess.Output(888, 8);
Thread.Sleep(100);

PortAccess.Output(888, 4);
Thread.Sleep(100);

PortAccess.Output(888, 2);
Thread.Sleep(100);

PortAccess.Output(888, 1);
Thread.Sleep(100);

PortAccess.Output(888, 3);
Thread.Sleep(100);

PortAccess.Output(888, 7);
Thread.Sleep(100);

PortAccess.Output(888, 15);
Thread.Sleep(100);

PortAccess.Output(888, 31);
Thread.Sleep(100);

PortAccess.Output(888, 14);
Thread.Sleep(100);
if (a == 1)
{
PortAccess.Output(888, 0);
break;
}
}
}

}
}

LP in hvala.

Kaj si pa to ustvaru?
volatile int a; to napiš namesto samo int a;
pa naredi tako, kot je Monster reku, ločen thread.
Pa še neki:

const int [] arr = {4,10,17,27,31,30,28,24,16,8,4,2,1,3,7,15,31,14};
foreach (int i in arr)
{
   PortAccess.Output(888, i);
   Thread.Sleep(100);
}

Namesto da maš 100 enakih vrstic kode!!!!!

.. se pa nauči ... pomojem ti bo vzelo manj kot dan časa ;) ... kr hrabro dalje!

const int [] arr = {4,10,17,27,31,30,28,24,16,8,4,2,1,3,7,15,31,14};
foreach (int i in arr)
{
   PortAccess.Output(888, i);
   Thread.Sleep(100);
}

Error 1 'arr' is of type 'int[]'. A const field of a reference type other than string can only be initialized with null.

Bral sem da moraš nekaj readonly narest, pa ne razumem prav dobr.


ZA THREAD:

Sem skopiral kodo in je prišlo do napake:
Error 1 No overload for 'funThread' matches delegate 'System.Threading.ParameterizedThreadStart'

Našel neko stvar ki je nekomu pomagala:

public void funThread(object uri)
{
Uri funThreadUri = uri as Uri;
funThread(uri);
}

public void funThread(Uri uri)
{
PortAccess.Output(888, 4);
Thread.Sleep(100);

PortAccess.Output(888, 10);
Thread.Sleep(100);

PortAccess.Output(888, 17);
Thread.Sleep(100);
}

Ko zaženbem program pride do napake in se pojavi okno za pošli al i ne pošlji poročilo napake.

Lahko uporabiš tudi Application.DoEvents