TStringList* availableComPorts = new TStringList();
TRegistry *Registry = new TRegistry(KEY_READ);
AnsiString portNb ="";
 
Registry->RootKey = HKEY_LOCAL_MACHINE;
// The com ports are administered in the following directory.
// false, because no entry is supposed to be created.
Registry->OpenKey("HARDWARE\\DEVICEMAP\\SERIALCOMM", false);
 
// Extract the COM port names and store them.
Registry->GetValueNames(availableComPorts);
// List the available COM ports in the corresponding combo box.
for (int i(0); i < availableComPorts->Count; i++)
{
    portNb = Registry->ReadString(availableComPorts->Strings[i]);
    ComboBox1->AddItem(portNb, NULL);
}
delete Registry;
delete availableComPorts;