How do I eject/change a floppy disk/cdrom in QEMU?
In the monitor, the eject command will remove the disk. The change command will insert a new one. Note that if you are changing real disks (e.g. qemu is using the host cdrom drive and you are changing physical cdrom disks) then it is recommended that you eject the cdrom from qemu, and then change physical cdrom disks, and then use the change command in the monitor to reinsert the host cdrom disk.