Browse Prior Art Database

Collection And Checking of Predicted Signature On Computers

IP.com Disclosure Number: IPCOM000102117D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 71K

Publishing Venue

IBM

Related People

Barucchi, G: AUTHOR [+3]

Abstract

Disclosed is a system allowing the collection and the checking of the predicted signatures for any number of self-tested chips being mounted on cards or boards. The signature prediction can be theoretically accomplished with the help of a theorem using the properties of the linear shift registers as demonstrated in (*). This theorem states that the end value of the signature register MISR (MISR stands for Multiple Inputs Shift Register) can be any chosen value provided that the initial value of the MISR was computed from this chosen value and the one got from the simulation of the corresponding chip hardware. This article shows how the hereabove principle can be implemented in LSSD (level sensitive scan design) designs.

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Collection And Checking of Predicted Signature On Computers

       Disclosed is a system allowing the collection and the
checking of the predicted signatures for any number of self-tested
chips being mounted on cards or boards. The signature prediction can
be theoretically accomplished with the help of a theorem using the
properties of the linear shift registers as demonstrated in (*). This
theorem states that the end value of the signature register MISR
(MISR stands for Multiple Inputs Shift Register) can be any chosen
value provided that the initial value of the MISR was computed from
this chosen value and the one got from the simulation of the
corresponding chip hardware. This article shows how the hereabove
principle can be implemented in LSSD (level sensitive scan design)
designs.

      During the LSSD flush (i.e., A and B clock active on the SRL
latches), all the LSSD chains of a chip are serially connected in
order to force their initialization including the PRPG (Pseudo Random
Pattern Generator) and the MISR.

      Now the method proceeds as follows:
      1)   After the flush operation, the MISR value is all '1's.
 2)   The simulation is run using a tool which simulates the Self-
Test sequences, starting from a MISR with the all '1's value.
 3)   The new initial value of the MISR is computed from this simu
lated signature and the desired final signature. This compu
tation is performed with the help of a program which cycli
cally left rot...