if (document.images) {
    crystalsbuttonup       = new Image();
    crystalsbuttonup.src   = "images/btnCrystals.png" ;
    crystalsbuttondown     = new Image() ;
    crystalsbuttondown.src = "images/btnCrystals_on.png" ;
}
if (document.images) {
    oscillatorsbuttonup       = new Image();
    oscillatorsbuttonup.src   = "images/btnOscillators.png" ;
    oscillatorsbuttondown     = new Image() ;
    oscillatorsbuttondown.src = "images/btnOscillators_on.png" ;
}
if (document.images) {
    vcxobuttonup       = new Image();
    vcxobuttonup.src   = "images/btnVCXO.png" ;
    vcxobuttondown     = new Image() ;
    vcxobuttondown.src = "images/btnVCXO_on.png" ;
}
if (document.images) {
    tcxobuttonup       = new Image();
    tcxobuttonup.src   = "images/btnTCXO.png" ;
    tcxobuttondown     = new Image() ;
    tcxobuttondown.src = "images/btnTCXO_on.png" ;
}
if (document.images) {
    ocxobuttonup       = new Image();
    ocxobuttonup.src   = "images/btnOCXO.png" ;
    ocxobuttondown     = new Image() ;
    ocxobuttondown.src = "images/btnOCXO_on.png" ;
}

if (document.images) {
    quickturnbuttonup       = new Image();
    quickturnbuttonup.src   = "images/btnQuickTurn.png" ;
    quickturnbuttondown     = new Image() ;
    quickturnbuttondown.src = "images/btnQuickTurn_on.png" ;
}


function buttondown( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "up.src" );
    }
}