Browse Prior Art Database

Multi-Link Communicator

IP.com Disclosure Number: IPCOM000120545D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 5 page(s) / 199K

Publishing Venue

IBM

Related People

Christianson, MD: AUTHOR [+2]

Abstract

A Multi-Link Communicator (MLC) is a communications network which directs DMA traffic between any of a number of input/output nodes while providing reliable protection against erroneous internode connections and electrostatic discharge (ESD). The MLC ensures that no more than one output node can connect to a particular input node at any given time. It significantly simplifies and reduces the control logic which would otherwise be required within a node to direct DMA traffic. The MLC centralizes the node interconnection logic, making it more manageable and easier to design and simulate.

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This is the abbreviated version, containing approximately 36% of the total text.

Multi-Link Communicator

      A Multi-Link Communicator (MLC) is a communications
network which directs DMA traffic between any of a number of
input/output nodes while providing reliable protection against
erroneous internode connections and electrostatic discharge (ESD).
The MLC ensures that no more than one output node can connect to a
particular input node at any given time.  It significantly simplifies
and reduces the control logic which would otherwise be required
within a node to direct DMA traffic.  The MLC centralizes the node
interconnection logic, making it more manageable and easier to design
and simulate.

      The MLC is a communications switching network which ties
together a system DMA path and a number of input/output paths (see
Fig. 1).  The control logic which interfaces with such an I/O path
can be referred to as a 'node'.  The particular application for which
the MLC was originally designed had six I/O nodes, of which each was
attached to a serial link which, in turn, was attached to an
arrangement of direct access storage devices (DASDs).

      A node consists of a transmitter entity and a receiver entity.
During full functional operation, a transmitter may send data out on
the link to which it is connected.  It obtains the data from another
link's receiver or from the system DMA path.  A receiver may obtain
data from the link to which it is connected and will store it in one
of its data buffers.  It is possible to have various combinations of
the transmitters and receivers operating simultaneously.  For
example, node 0's transmitter could be transmitting data it is
reading from node 4's receiver.  Node 4's transmitter could be
transmitting data it is reading from node 0's receiver.  Node 3 might
transmit data that it got from the system DMA path and then its
receiver might read the same data in from the link a short time
later.  This data might then be read by node 2's transmitter.  Node
5's receiver may be reading data from its link and storing it into
one of its buffers while node 1's transmitter is reading data from
node 5's other buffer, etc.

      The transfer possibilities are extensive and the trafficking
can become quite complex.  Furthermore, there exists the possibility
that a hardware failure, perhaps caused by ESD (electrostatic
discharge), could result in erroneous connections between the nodes.
With addresses within any two given nodes often differing by only one
or two bits and with all the nodes interconnected, it is important
that the hardware be designed to avoid situations which could result
in misconnections among the nodes.

      The MLC (see Fig. 2) contains the interconnection logic
necessary to allow the six nodes to communicate with each other and
with the system DMA path.  The MLC is a collection of all the
multiplexers needed to connect each of the six destination nodes with
the other five node's receivers and with the system DMA path.  As
such, there are...