Browse Prior Art Database

Early Decoding Method for Intel 82385 Cache Controller-Based Systems

IP.com Disclosure Number: IPCOM000101131D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Capps, LB: AUTHOR [+5]

Abstract

This article describes reduction of decode time for system bus cycles for Intel 82385 cache controller-based systems.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 69% of the total text.

Early Decoding Method for Intel 82385 Cache Controller-Based Systems

       This article describes reduction of decode time for
system bus cycles for Intel 82385 cache controller-based systems.

      In the 82385 cache controller architecture the Intel 80386
starts a bus cycle which can be forwarded to the system bus one or
more states later.  The forwarding of the 80386 bus cycle to the
system bus is conditional and depends on cache and system bus
activity.  Typically, the decoding process is initiated once the
80386 cycle is forwarded to the system bus.

      The method disclosed herein provides the ability to decode one
state earlier the system bus cycle definitions. The bus cycle
definition refers to the type of cycle, address, and/or what
subsystem the cycle is addressing.

      By using the 82385 cache controller the interaction of the
80386 and the 82385 allow a way to implement early decoding of system
bus cycle definitions.  Fig. 1 depicts this interaction by showing a
timing relationship of an 80386 cycle being forwarded to the system
bus by the 82385.

      In state 1, the 80386 bus cycle definition becomes valid along
with the address strobe (ADS).  Since this 80386 bus cycle definition
may later be forwarded to the system bus, the decode process can
begin immediately in state 1. The state 1 decode process can then be
referred to as "early decoding" since the bus cycle information has
not yet been made available to the system bus.

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