Get Directory (18)
         +-----------------------------------------------------------------+
         | Operation| Position |DataBuffer| DataBuff |    Key   |    Key   |
         |          |  Block   |          |  Length  |   Buffer |   Number |
 +-------+----------+----------+----------+----------+----------+----------|
 |Expects|BT_GET_DIR|          |          |          |          |   Drive<-+-+
 |-------+----------+----------+----------+----------+----------+----------| |
 |Returns|          |          |          |          |   Path   |          | |
 +-------------------------------------------------------------------------+ |
                                                                             |
                                                                             |
Get current working directory.                                               |
                                                                             |
Key buffer must be 64 characters long.                +------------------+   |
                                                      |  0 Current Drive |   |
                                                      |  1 A:            |   |
Current Position: Not set                             |  2 B:            |---+
                                                      |    ... etc.      |
                                                      +------------------+