An example of traced I/O:

 	$ LD SHOW/TRACE/ENTRIES=(12,23)/IOSB=COMBINATION LDA1:

          I/O trace for device _THEBUG$LDA1:
     24-FEB-1994 16:36:56.31 on node THEBUG::

 Start Time  Elaps   Pid        Lbn    Bytes  Iosb   Count  Function
 -------------------------------------------------------------------
 20:52:30.01 00.02 202000C4          5   512 NORMAL    512 READPBLK
 20:52:30.03 00.03 202000C4          5   512 NORMAL    512 WRITEPBLK|DATACHECK
 20:52:30.07 00.00 202000C4          0     0 NORMAL      0 UNLOAD
 23:16:18.05 00.00 202000C5          0    32 NORMAL      0 SETMODE|LINE_OFF
 23:16:30.13 00.00 202000C5          0    11 NORMAL      0 SETMODE|LINE_ON|NEWLINE
 23:17:05.70 00.05 202000C5          0     0 NORMAL      0 PACKACK|INHERLOG
 23:17:05.76 03.22 202000C5          1   512 NORMAL    512 READPBLK
 23:17:09.00 00.67 202000C5     608509   512 NORMAL    512 READPBLK
 23:17:09.67 00.03 202000C5     608510   512 NORMAL    512 READPBLK
 23:17:09.70 00.27 202000C5     608334   512 NORMAL    512 READPBLK
 23:17:09.97 00.00 202000C5     608334   512 WRITLCK     0 WRITEPBLK
 23:17:10.04 00.29 202000C5     608508   512 NORMAL    512 READPBLK