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Browse Prior Art Database

Method of Providing Local Arbitration Control for Personal Computers

IP.com Disclosure Number: IPCOM000106371D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Boury, BF: AUTHOR [+4]

Abstract

Described is a hardware implementation to provide personal computers equipped with a Micro Channel* (MC) facility the ability to have local arbitration control of multiple direct memory access (DMA) functions.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

Method of Providing Local Arbitration Control for Personal Computers

      Described is a hardware implementation to provide personal
computers equipped with a Micro Channel* (MC) facility the ability to
have local arbitration control of multiple direct memory access (DMA)
functions.

    Normally, only one central arbitration control point (CACP)
function exists on a MC.  The primary output of the CACP is the
arbitration/grant (ARB/GNT) signal which controls when devices are
allowed to arbitrate.  All other devices on the MC must monitor this
signal as an input.  Since the CACP function can be combined with DMA
functions, the CACP function cannot be implemented when multiple DMAs
are used.  In order to provide increased functionality for multiple
DMA operations, an external pin is added to the circuitry to disable
the CACP so that the arbitration can be under the control of local
arbitration control point (LACP) mode.  In this mode, it is possible
to connect several DMA's in parallel with the primary DMA, typically
the one in CACP mode.  In addition, this operation can be used in
building high speed bus master circuits on the MC.

    When operational in LACP mode, the DMA monitors the arbitration
bus as well as the ARB/GNT.  The LACP logic has three major functions
as follows:

    1.  Monitors MC arbitration to determine if an internal DMA
channel
  has won the bus and instructs the DMA to begin transfers.

    2.  Provides the HOLD/HLDA handshake n...