Browse Prior Art Database

Bus Control Line Parity Error Reset

IP.com Disclosure Number: IPCOM000105485D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Paulson, PJ: AUTHOR

Abstract

Described is a Bus reset function. The Bus must have multiple bus masters and can have either distributed or central arbitration. A parity error detected on the bus control lines will get propagated to the master reset Bus unit which then initiates a reset sequence which resets each bus unit to a specific initialization state.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 75% of the total text.

Bus Control Line Parity Error Reset

      Described is a Bus reset function.  The Bus must have multiple
bus masters and can have either distributed or central arbitration.
A parity error detected on the bus control lines will get propagated
to the master reset Bus unit which then initiates a reset sequence
which resets each bus unit to a specific initialization state.

      One Bus master is designated as the reset controller.  That
unit will signal to the other bus units to do a Bus reset.  To signal
the designated bus master to activate RESET, since the designated bus
master may not see the original parity error, any Bus master that
sees a parity error on any Bus control line will drive out bad parity
over all control lines.  Eventually the designated Bus master will
see a parity error and turn on RESET.

      When a Bus master sees a RESET or control line parity error it
can no longer arbitrate for the Bus, accept commands or data from any
other Bus unit, and must mark unfinished outbound commands and data
for retry.  Once RESET goes active a Bus unit will follow a
predetermined reset sequence.  A possible sequence could be:

1.  Drive good parity on all bus control lines, but do not check
    parity, RESET still active.

2.  Continue to drive good parity and then start checking parity,
    RESET still active.

3.  Set the arbitration logic to known initialization state, RESET
    still active.

4.  If bad parity detected, then drive bad par...