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Browse Prior Art Database

Parity Checking of a RISC Register File/Data Flow

IP.com Disclosure Number: IPCOM000100059D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Kahle, JA: AUTHOR

Abstract

This disclosure describes a way to reduce the amount of logic required to check parity in a RISC architecture. The parity is also checked so that it will not create any critical timing paths.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 65% of the total text.

Parity Checking of a RISC Register File/Data Flow

       This disclosure describes a way to reduce the amount of
logic required to check parity in a RISC architecture.  The parity is
also checked so that it will not create any critical timing paths.

      The central data flow core of a RISC processor circulates
around the register file.  The register file receives data from the
results of the execution unit, data from memory, and data from I/O.
The register file also produces the data for the execution unit.

      In a RISC architecture there are two or three main latches
between the decode phase and the exec phase of the pipe.  Most of the
data that feeds the exec phase of the pipe must go through these
latches.  This makes an ideal location for the parity checkers.
These latches also have non-inverting buffers after them because of
the nature of the fan-out correction.  Putting three parity checkers
after these buffers does not affect any critical path.  Since the
parity checkers are located after a latch, there is a whole cycle
available to check the parity.  This makes an ideal location for the
parity checkers from a timing standpoint.

      The central location of these parity checkers also allows three
parity checkers to check a large portion of data flow.  Any data
coming from the register file must pass through the three latches, so
these parity checkers will check the register file when it is used.
These parity checkers will also check...