Browse Prior Art Database

Improved Method of Implementing a Programmable Decoding Circuit

IP.com Disclosure Number: IPCOM000101210D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Voigt, WG: AUTHOR

Abstract

Described is a Modular Programmable Decoding Circuit which is faster and easier to change than conventional Programmable Decoding Circuits.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Improved Method of Implementing a Programmable Decoding Circuit

       Described is a Modular Programmable Decoding Circuit
which is faster and easier to change than conventional Programmable
Decoding Circuits.

      In a programmable decoding circuit, placing a binary value i on
the input causes the (i+1)th enabled output to become active.  The
outputs which are not enabled are ignored in the decode.  As in a
regular decoding circuit, a given binary input can cause at most one
output to become active.  However, the programmable decoding
circuit's outputs must respond to different binary inputs depending
upon the number of outputs which have been enabled.

      The basic module for the new programmable decoding function is
represented in Fig. 1.  An arbitrarily large selection circuit can be
built by cascading basic modules (see Fig. 2.)

      Before operation of the programmable decoding unit, the enables
of the modules must be set.  The outputs of modules not enabled
cannot be selected.  The incrementers for the selection circuit are
connected in series allowing the circuit to count the number of
outputs that have been enabled.  For the jth module, the incrementers
from the 0th module to the (j-1)th module count the number of enables
that are active before the jth module.  The incrementer in the jth
module increments the count if the jth enable is active and makes
this number available to the (j+1)th module.  For a standard decoding
unit, the...