Asus A55A Manual page 58

3. Hold the disc by the edge and face the disc's printed side up.
Push down on both sides of the disc's center until the disc snaps
onto the hub. The hub should be higher than the disc when
correctly mounted.
4. Slowly push the drive's tray back in. The drive will begin reading
the table of contents (TOC) on the disc. When the drive stops,
the disc is ready to be used.
It is normal to hear as well as feel the CD spinning with great
intensity in the CD drive while data is read.
58 Notebook PC User Manual