Command               Operation
-------               ---------
CMD_CLEAR             Clear the keyboard input buffer.  Removes any key
                      transitions from the input buffer.

KBD_ADDRESETHANDLER   Add a reset handler function to the list of
                      functions called  by the keyboard device to clean up
                      before a hard reset.

KBD_REMRESETHANDLER   Remove a previously added reset handler from the
                      list of functions called by the keyboard device to
                      clean up before a hard reset.

KBD_RESETHANDLERDONE  Indicate that a handler has completed its job and
                      reset could possibly occur now.

KBD_READMATRIX        Read the state of every key in the keyboard.  Tells
                      the up/down state of every key.

KBD_READEVENT         Read one (or more) raw key event from the keyboard
                      device.


Exec Functions as Used in This Chapter
--------------------------------------
AbortIO()             Abort a command to the keyboard device.

AllocMem()            Allocate a block of memory.

CheckIO()             Return the status of an I/O request.

CloseDevice()         Relinquish use of the keyboard device.

DoIO()                Initiate a command and wait for it to complete
                      (synchronous request).

FreeMem()             Free a block of previously allocated memory.

OpenDevice()          Obtain use of the keyboard device.

SendIO()              Initiate a command and return immediately
                      (asynchronous request).

WaitIO()              Wait for the completion of an asynchronous request.
                      When the request is complete the message will be
                      removed from reply port.


Exec Support Functions as Used in This Chapter
----------------------------------------------
CreateExtIO()         Create an extended I/O request structure.  This
                      structure will be used to communicate commands to
                      the keyboard device.

CreatePort()          Create a signal message port for reply messages from
                      the keyboard device.  Exec will signal a task when a
                      message arrives at the port.

DeleteExtIO()         Delete an extended I/O request structure created by
                      CreateExtIO().

DeletePort()          Delete the message port created by CreatePort().