Sharp mz-3500 Manual For Use page 191

Section A:
System interface
Error code 9 will be returned when the file had been closed and an error
occurred during closing, so that the FCB had to be marked as invalid.
If the error handing mode is set to automatic return, any physical
errors are returned in register H, in which case A is set to 0FFH.
EOS system manual
Daeumling & Zimmermann
Page 54