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Simulation Technique for Array Rules Checking

IP.com Disclosure Number: IPCOM000108535D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 95K

Publishing Venue

IBM

Related People

Carter, JL: AUTHOR [+3]

Abstract

This article discloses a technique for simulating logic gates and memory using symbolic values. The symbolic values are suitable for verifying that the latches and arrays embedded in a computer design can be initialized to arbitrary independent values.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 54% of the total text.

Simulation Technique for Array Rules Checking

       This article discloses a technique for simulating logic
gates and memory using symbolic values.  The symbolic values are
suitable for verifying that the latches and arrays embedded in a
computer design can be initialized  to arbitrary independent values.

      There are n symbolic values, denoted a(1), a(2), ..., a(n), and
their negatives, 5a(1), 5a(2), ..., 5a(n).  In addition, there are
the two logic values 0 and 1, and the value X which represents
"unknown".  As is usual in simulation techniques, one is given an
assignment of values to the primary inputs, latches and memory cells
of a design, and the values are propagated through the logic blocks.

      The rules for the propagation of values through AND and NOT
blocks are tabulated in Fig. 1.  The rules for other Boolean
operations (e.g., NAND, NOR, and OR) can be derived from these.  In
the figure, a(i) and a(j) represent any of the symbolic values and
5a(i) and 5a(j) represent their negatives.

      A READ operation of an array can be simulated by first
examining the bits of the address to be read.  If each such bit is
either a '0' or a '1', then the contents of the corresponding array
cell are placed on the data output lines.  Otherwise, X's are placed
on the output lines.

      To simulate a WRITE operation, again the address bits need to
be examined.  If each one is a '0' or '1', then the values on the
data lines are written into...