Browse Prior Art Database

Internal Critical Point Monitoring Mechanism

IP.com Disclosure Number: IPCOM000109377D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Millas, RJ: AUTHOR [+3]

Abstract

This article describes a method and mechanism utilizing a multiplexer with output to chip I/O pin to provide monitoring of internal points.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Internal Critical Point Monitoring Mechanism

       This article describes a method and mechanism utilizing a
multiplexer with output to chip I/O pin to provide monitoring of
internal points.

      Integrated circuit (IC) technology has evolved to a point where
the number of logic cells within a module can be in the tens of
thousands.  This high density reduces the amount of space necessary
on a card to perform its functions, thus more complex systems can be
built given the same space.

      A problem can occur when these high density modules are to be
tested.  Test methodologies have been developed such as
level-sensitive scan design (LSSD).  LSSDs contain a serial scan path
which is composed of all the latches within a given module.  A serial
pattern is propagated through the scan path and the output is
obtained for analysis. This philosophy is very effective at
determining if a module is functioning properly.  It is not only
useful for testing in manufacturing, but it can also be used for
debugging during development.  However, LSSD does not lend itself for
real-time monitoring of internal lines which is very critical in
solving timing problems.

      Presented herein is a method to monitor internal signals in
critical locations.  Due to the limited number of I/O pins on a
module, the number of critical signals that can be carried out
through the I/O pins is typically very small.  Therefore, a
multiplexer is used to select any one of numerous preselected
critical monitoring points.  The internal critical point monitoring
mechanism (ICPMM) is shown in functional bloc...