FYI from the BWG docs:
SBR CallsThe DSR supports the following CALLs in TI.Basic or the HRD-Menu with “K“: Call Files (x)With this CALL you can store the number of file buffers in VDP-Ram. For each open file there must be the same number of data buffers or you will get an error message. Possible values for (x) are from 1 to 9. Call 16SPTThis command switches the controller software to a disk format with 16 sectors per track in Double-Density, for those disk controllers that support it, that was planned for the predecessor of the TI Disk Controller PHP 1240 that never made it out of the beta stage and was never produced or sold..
However, this is the format of the HEXBUS-Disk Controller and the one that MYARC products used so disks in circulation in this format can be run (and are).
The command of 16SPT goes to all of the disk drives that are connected to the BwG Controller. Access to “normal“ Double-Density format is no longer possible and can only be done through a Ramdisk or a diskette with Single-Density..
The 16-Sector format remains in effect until switched back with a CALL 18SPT.
This change affects all programs that use the DSR for reading and writing.. Also formatting for most programs should function since these all use the individual DSR routines. Call 18SPTSwitches back to the “normal“ Double-Density format (18 Sectors per track)