[Tinyos-2-commits] CVS: tinyos-2.x/doc/txt tep113.txt,1.10,1.11

[Phil Levis]

Update of /cvsroot/tinyos/tinyos-2.x/doc/txt
In directory sc8-pr-cvs10.sourceforge.net:/tmp/cvs-serv29044

Modified Files:
	tep113.txt 
Log Message:
Edits from David Gay.


Index: tep113.txt
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/doc/txt/tep113.txt,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** tep113.txt	29 Mar 2008 01:05:45 -0000	1.10
--- tep113.txt	1 Apr 2008 17:00:51 -0000	1.11
***************
*** 281,300 ****
  Only the PC-to-mote communication path supports acknowledgements.
  SerialP does not request acknowledgements from the PC for two reasons.
! First, acks are not perfect reliability: they are used on the PC-to-mote
! path to raise reliability to a usable level. In the case of the PC-to-mote
! path, the UART receive buffer is typically a single byte, so a high interrupt
! load can easily lose (and sometimes does) a byte. This is in contrast
! to the PC receive buffer, which is much larger and does not have to
! deal with overflow. Second, adding support for acks would increase
! the code size and complexity of the serial stack. As code space is
! often at a premium, this would add little needed functionality at significant
! cost. Of course, any application that
! requires perfect reliability may layer its own scheme on top of the
! serial protocol.
  
  The acknowledgement protocol is stop-and-wait to minimize buffering on
  the mote side. This is considered more important on memory constrained
  devices than increased throughput in the PC-to-mote direction, which
! most applications only use for occasional contro transmissions.
  
  
--- 281,300 ----
  Only the PC-to-mote communication path supports acknowledgements.
  SerialP does not request acknowledgements from the PC for two reasons.
! First, acks are not perfect reliable: they are used on the
! PC-to-mote path to raise reliability to a usable level. In the case of
! the PC-to-mote path, the UART receive buffer is typically a single
! byte, so a high interrupt load can easily lose (and sometimes does) a
! byte. This is in contrast to the PC receive buffer, which is much
! larger and does not have to deal with overflow. Second, adding support
! for acks would increase the code size and complexity of the serial
! stack. As code space is often at a premium, this would add little
! needed functionality at significant cost. Of course, any application
! that requires perfect reliability may layer its own scheme on top of
! the serial protocol.
  
  The acknowledgement protocol is stop-and-wait to minimize buffering on
  the mote side. This is considered more important on memory constrained
  devices than increased throughput in the PC-to-mote direction, which
! most applications only use for occasional control transmissions.