Disable writing on removable disks

Hi,
There is a posibility to disable the floppy-disk and the CD-ROM to avoid writing ?
I want to let floppy to be available for reading, but to be disabled for writing. The same for CD-ROM
I have to halt system to write on removable disks, but also to have posibility to allow writing back at a certain moment .

I need a solution in any languages.

THANKS!!