Aurduino Oscilloscope

having a oscilloscope has been a dream for me since i started leaning electronics, because i can't afford buying an Oscilloscope( i never buy second hand electrical equipment ). Therefore i decided to solve my problem by myself, However i kinda failed.
The Arduino Oscilloscope has many problems such as its range ( ~ 1Khz :) ) and its scale ( there is no scale on the screen). the input also must be between 0 to 5 volt which is not a problem ( it can be increased by voltage dividers or using transistor). After all there are the Code for arduino and visual basic .... have some fun

**********************************Aurduino**************************

int incomingByte = 0;
const int analogInPin = 0;

int sensorValue = 0; // value read from the pot

void setup()
{
Serial.begin(115200);
pinMode(13,OUTPUT);
}


void loop()
{
sensorValue = analogRead(analogInPin);


Serial.println(sensorValue);


incomingByte=0;
delay(1);

}

NOTE: if u erase the delay, the computer will be left behind the data. Therefore the screen will be 20 sec behind what is actually happen .

*************************************Visual basic**************************


********* 3 text boxes and and a bottom are needed *****************
Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

sp1.PortName = TextBox1.Text

sp1.Open()
Dim myPen As Pen = New Pen(Color.GreenYellow, 5)

sp1.Write(1)
Dim i As Integer
Dim u As Decimal
Dim x As Decimal
Dim z As Integer
Dim x1 As Decimal
Dim voltager As Integer
Dim timerange As Integer
Dim timerangex As Integer

voltager = Val(TextBox2.Text)
timerange = Val(TextBox3.Text)

Dim a As String

Dim n As Single
n = 0
Me.CreateGraphics.Clear(Color.Black)
Do
n = n + 1
If n = (800 / timerange) Then
n = 0
Me.CreateGraphics.Clear(Color.Black)
End If

a = sp1.ReadLine

z = Val(a)
x = 5 / 1024 * z
u = (5 * voltager)

x = x * voltager
x = u - x


Me.CreateGraphics.DrawLine(myPen, timerange * n, x1 - 1, timerange * n, x)

x1 = x



Loop




sp1.Close()

End Sub

End Class
*******************************************************