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Coordination of Multiple Intelligent Bus Units by a Common Controller

IP.com Disclosure Number: IPCOM000122026D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 4 page(s) / 186K

Publishing Venue

IBM

Related People

Dennis, CA: AUTHOR [+2]

Abstract

This article describes a method of interconnecting multiple controllers via a bus, called the element control bus (ECB). An element supervisor unit (ESU) is the common, programmable controller, issuing "work" to the bus units using "dispatch" operations on the ECB.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 36% of the total text.

Coordination of Multiple Intelligent Bus Units by a Common Controller

      This article describes a method of interconnecting
multiple controllers via a bus, called the element control bus (ECB).
An element supervisor unit (ESU) is the common, programmable
controller, issuing "work" to the bus units using "dispatch"
operations on the ECB.

      When a bus unit has completed its work, an interrupt sequence
signal is sent to the ESU, coordinated operations involving more than
one bus unit can be established, with work posting and aborting
capabilities.
Element Control Bus Communication

      The ECB is the interface used by the ESU to control the
operations of functional elements attached to it.  The manager of the
ECB is the memory management unit (MMU) function of the ESU; it is
also a bus unit of the ECB.  As shown in Fig. 1, the ECB will
support up to 16 bus units.  Bus unit 0 is always the MMU function of
the ESU.  Bus units 1 and 2 are the bus interface units to the
PI-buses.  Other bus units represent the primary control points in
functional element modules.
Link Layer

      Transfers are performed on the ECB operate in a master-slave
relationship.  Mastership of the ECB is established through an
arbitration sequence.  The ECB manager (a part of the MMU function of
the ESU) signals the beginning of the arbitration sequence.  At that
time any bus unit in need of the ECB activates its bus request line
which is hardwired to a particular bit position on the address/data
bus.  The ECB manager picks the highest priority requester as the
next master of the ECB and subsequently places its ID on the ECB.
Following the arbitration sequence, the new master performs a command
sequence.  The new master places a word count on the ECB which is
received by the ECB manager.  The master then selects the slave by
placing on the ECB the slave's ID; at the same time, the master
presents a command and the high-order bits of an address (if an
address is required by the operation specified by the command).  The
master subsequently presents the low-order bits of the address to the
slave.  Following the command sequence, the transmitter of data
initiates a data transfer sequence.  If the direction of data is
toward the slave, then the master is the transmitter and initiates
the sequence.  If the direction of data is toward the master, then
the slave is the transmitter and initiates the sequence.  The ECB
manager maintains the word count and, when all words have been
transferred, signals the end of the transfer to both the master and
slave.  Errors in the command, address, or data can be signaled, and
the ECB manager will initiate a new arbitration sequence.  The master
may retry any operation which ended in error one time.  The ECB
manager can also signal an error if no data words are exchanged in
8192 bus cycles.  Any time a bus transfer operation ends, either
successfully or in error, the ECB manager will initiate a new
...