DMEDIUM_FORMAT [(#channel)] or


Location SMSQ/E v2.73+

This function returns a number representing the operating system under which the medium (or hard disk partition) on which the specified file or directory is located (or to which the specified channel is open) was created. If no parameter is specified, it looks to channel #3 (or #1 if #3 is not open).

The values returned currently are:

  • 1 QDOS or SMSQ or SMSQ/E
  • 2 DOS or TOS


This function does not appear to work on Falkenberg hard disk interfaces where it always returns 255.


DIR will provide this information also on Level-3 device drivers. DMEDIUM_DENSITY allows you to check the medium’s density. There is currently no way to format a disk in a format other than QDOS or SMSQ/E without the ATARI_rext commands which were available with the ST/QL emulators from Jochen Merz, or without specialist software (some of which is public domain).