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Browse Prior Art Database

Processor Bus Arbitration With Dead

IP.com Disclosure Number: IPCOM000099316D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Kahle, JA: AUTHOR

Abstract

This disclosure describes a way to control bus with dead cycles. This disclosure is used in context of a system with 3 chips that are interconnected a Processor Bus (PBUS). Dead cycles (no drivers are are used to simplify the clocking requirements for system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 93% of the total text.

Processor Bus Arbitration With Dead

       This disclosure describes a way to control bus with dead
cycles.  This disclosure is used in context of a system with 3 chips
that are interconnected a Processor Bus (PBUS).  Dead cycles (no
drivers are are used to simplify the clocking requirements for
system.

      In this system, the PBUS transfers information between
Instruction Cache Chip (ICU), Fixed Point Chip (FXU) and Controller
Chip (SCU).  To simplify the clocking the PBUS must have one dead
cycle between chips driving the bus.  This allows one whole for one
chip's drivers to turn off and another chip's to turn on.

      The FXU is the bus master.  To insure that there are cycles on
the PBUS, the FXU uses the arbitration lines control when the other
chips are driving the bus.  Since SCU is always a slave on the PBUS,
there are no lines between the FXU and SCU.  There are two lines
between the FXU and ICU.  The two lines called PBUS_ICREQ and
PBUS_ICGRNT.

      The PBUS_ICREQ line is driven by the ICU to indicate the ICU
would like the PBUS.  The PBUS_ICGRNT line is by the FXU to indicate
that the ICU can drive the  The ICU wins arbitration for the PBUS
when both the and PBUS_ICGRNT lines are active.  After the ICU won
arbitration, it can drive the PBUS on following

      The figure represents some possible arbitration timings.
observations should be noted from the figure.  First, FXU can control
the dead cycles when it activates the l...