Hi Xanthos
I think Pioneer has a patent on that slot-load and i know they have DVD and CDROM´s that uses this type of tray.
However, a standard cdrw or a dvdxx should have 4 tabs that you flip over the disc to make it stay on the tray. At least on the last 5 or 6 drives i have had, the tabs have been there. On Sony´s drives for sure.
* TheLostSwede hits the eject buttons on all drives
I´m dead wrong here, lol. The 2 i have now doesn´t have the tabs. Wonder when they decided to remove those?
On my PS2, no tabs are available but mounting it vertically works as good as horizontally and the same should be for theese type of drives. If you have a CDxx now, check it´s user manual if vertical mounting is supported or not.