Imports System.IO
 
Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim memory(4096) As Byte
        Dim V(16) As Char
        Dim I As String
        Dim pc As Integer
        Dim gfx As Bitmap = New Bitmap(My.Computer.FileSystem.SpecialDirectories.Desktop & "\test.png")
        Dim delay_timer As Char
        Dim sound_timer As Char
        Dim stack(16) As Short
        Dim sp As Short
        Dim opcode As String
        Dim key As Char
        Dim memoryPosition As Short
 
        Dim openfiledialog As New OpenFileDialog
        openfiledialog.ShowDialog()
 
        memory = System.IO.File.ReadAllBytes(openfiledialog.FileName)
 
        While (1)
 
            opcode = Hex(memory(pc)) & Hex(memory(pc + 1))
 
 
            If opcode.StartsWith("A") Then
 
                ' Index Register Instruction

                For b = 1 To opcode.Length - 1
                    I &= opcode(b)
                Next
 
            End If
 
            If opcode.StartsWith("D") Then
 
                Dim x As Integer
                Dim y As Integer
                Dim height As Integer
                Dim width As Integer
 
                x = CLng("&H" & opcode(1))
                y = CLng("&H" & opcode(2))
 
                height = CLng("&H" & opcode(3))
 
                For b = 0 To height
                    gfx.SetPixel(x, y, Color.Gray)
                    PictureBox1.Image = gfx
                Next
 
                For a = 0 To 16
                    gfx.SetPixel(x + a, y, Color.Gray)
                    PictureBox1.Image = gfx
                Next
 
            End If
            pc += 2
        End While
 
    End Sub
End Class