Tandy 1000 SL Technical Reference Manual page 557

Software
CF
=
0: Noerror
CF
=
1 : Illegal parameter
Read DASD Type
Return the change line status.
Entry Conditions
AH
=
15H
DL
=
drive number (0-1 if Tandy 10000 TL; 0-1 if Tandy
1000 SL)
Exit Conditions
CF
=
1:
Operation was not successful. Previous versions
AH
=
1 : Invalid command.
CF
=
0: Operation was successful
AH
=
0: Drivenotpresent
of the Tandy 1000 will return CF=
1.
=
1:
=
2:
Diskette, no change line available
Diskette, change line available
36.