Browse Prior Art Database

Serial Channel Connection Buffer

IP.com Disclosure Number: IPCOM000120092D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 98K

Publishing Venue

IBM

Related People

Kaiser, JM: AUTHOR [+3]

Abstract

Disclosed is a method of receiving data from a serial link. (Image Omitted)

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Serial Channel Connection Buffer

      Disclosed is a method of receiving data from a serial
link.

                            (Image Omitted)

      This article covers the connection frame buffer of the port
adapter (PA).  This buffer has many functions and solves many
problems for an optical switch (or other system):
      1 - Synchronizes all incoming data from the optical link to the
switch.  This includes both frame type data and special sequences.
      2 - Captures, holds, and releases connection frames (data
packets).
      3 - Correctly passes the incoming 10 bit code's disparity so
that the data stream can be passed without decoding and encoding.
      4 - Checks for write/read pointer overruns during long
sequences and corrects (resyncs) the pointers without loss of data.
      5 - Cleans out frames as they are read so that frame fragments
are not left in the buffer in the event of a write error caused by
a link problem.

      DETAIL INFORMATION
      1 - The connection buffer serves as a sync buffer for the PA.
The data is written with the receive clock and read with the switch
system clock.  A "writing" signal goes from the write side to the
read side to initiate the reading process (see the figure).
      The port adapter writing always starts at address 0 so that no
address needs to be passed from writing to receiving logic.

      2 - Whenever the PA recognizes a connection frame, it must hold
the frame until the connection is made and then pass it on (assuming
no errors).  The connection buffer provides this function.
      If the read logic is able to execute connections, it looks for
connection frames whenever the write logic starts to write.  If the
start of a connect frame is found upon reading the buffer, the read
logic sets the hold signal to the write logic.
      When the write logic sees the hold signal come on, it completes
the frame in progress and then will not write until the hold goes
away.
      The read logic executes the connection, reads and releases the
captured frame, and then turns hold back off.  More frames and
special sequences can now be sent.

      3 - The link data stream is encoded in a special 10-bit code.
Each data value has two code point with different "disparity".  The
code is viola...