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Apparatus for Interconnecting a Channel having a Parallel Bus with a Control Unit having a Serial Link

IP.com Disclosure Number: IPCOM000106867D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 126K

Publishing Venue

IBM

Related People

Mills, PR: AUTHOR [+3]

Abstract

Disclosed is a converter apparatus that enables new IBM serial control units (CUs) to operate on older IBM parallel OEMI channels. The converter enables a new serial CU to operate at a significantly increased maximum distance of up to 3.122 kilometers from the channel; whereas a parallel CU cannot operate more than up to 0.122 kilometer from the channel.

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This is the abbreviated version, containing approximately 51% of the total text.

Apparatus for Interconnecting a Channel having a Parallel Bus with a Control Unit having a Serial Link

      Disclosed is a converter apparatus that enables new IBM serial
control units (CUs) to operate on older IBM parallel OEMI channels.
The converter enables a new serial CU to operate at a significantly
increased maximum distance of up to 3.122 kilometers from the
channel; whereas a parallel CU cannot operate more than up to 0.122
kilometer from the channel.

      The converter attaches a parallel OEMI channel to a cooperating
serial CU at extended distances.  The total OEMI CU function consists
of a converter unit connected through a serial link to a cooperating
serial CU.  The proprietary serial protocols are described in [1].
The converter unit has the appearance of an OEMI CU to its attached
parallel OEMI channel.  The serial link between the converter and its
CU can be up to 3 kilometers long.

      Current OEMI channels require that the parallel OEMI CUs be no
further than 400 feet (0.122 kilometer) from the processor/channel
mainframe.  Technology limitations further reduce this distance
incrementally to 295 feet as the number of CUs attached increases
from one to eight.  Certain CUs with critical response times must be
attached at significantly less than 400 feet.  Customers need
distances much greater than 400 feet between their CUs and their
processor/channel complexes to fulfill their expanding computing
requirements.  Customers having older processors with OEMI parallel
channels cannot attach the new IBM serial CUs without buying a new
IBM processor with serial channels.  Customers are reluctant to
change their processors and CUs all at once, and the converter allows
them to make incremental changes to their configuration.

      The total OEMI CU function was partitioned between a "converter
end" attached to an OEMI channel and a "CU end" which is remotely
attached via a serial fiber-optic link.  The "converter end" is
referred to simply as the "converter", and the "CU end" is referred
to simply as the "CU".  The CU is a new IBM serial CU that is capable
of attaching either to a converter or to a new IBM serial channel.
The serial link may contain an optional serial dynamic switch, which
allows multiple converters and multiple serial channels to all be
configured to the same CU.  (However, each converter may be
configured to only one CU.)  Since the converter and its CU may be
separated by a serial link at distances up to 3 kilometers, then the
customers distance restriction for future growth is greatly
alleviated.

      The Figure shows a high-level diagram of conceptual boundaries
of control.  The OEMI channel's control of the converter must conform
to the OEMI architecture, which is defined by [2].  Serial link
communications between the converter and the CU are defined by the
9035 document mentioned previously.  The serialized characters
flowing on the serial link are defined in [3]. ...