DMEDIUM_DENSITY [(#channel)] or
This function returns a number representing the density of the medium on which the specified file or directory is located, or to which the specified channel is open. If no parameter is specified, it looks to channel #3 (or #1 if #3 is not open). An error will occur if the specified channel is not open or the given file does not exist.
The value returned is:
0 Non-directory device
1 Double Density
2 High Density
3 Extra Density
255 Hard disk or ram disk as they have no density.