TP.WR9 - write to a 9-channel tape.

B:
   status = tp.wr9( unit, buffer, bytes );

C:
   #equate tp_wr9 tp.wr9
   int tp_wr9(FILE *unit, void *buffer, int bytes );

unit: is an open I/O unit associated with a 9-channel tape.
buffer: points to a buffer holding the data you want to write to the tape.
bytes: is the number of bytes of data you want to write.
status: is the number of bytes written, if the I/O operation was successful. If an I/O error occurs, "status" receives the negative of the major error status.

TP.WR9 writes the requested number of bytes onto a 9-channel tape from the specified buffer.