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8-Bit Pla Adder

IP.com Disclosure Number: IPCOM000047380D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Rinaldi, M: AUTHOR

Abstract

A logic array adder for executing the function S, COUT = A plus B plus CIN where S, A, B are eight-bit binary operands (Si), (Ai), (Bi) can be organized into one AND-array 1 and two OR-arrays 2, 3 each of fourteen rows, instead of the natural twenty five rows, by partitioning thirteen of the fourteen rows of the AND-array and grouping the product terms in a particular way. In addition, the inputs are entered into the AND-array as bit pairs Ai Bi via decoders 4, each having four output lines, only one of which lines is energized at a TIME, and the outputs are generated from the OR-arrays by Exclusive OR circuits 5 responsive to pairs of OR-array columns. The resultant logic array is of reduced area and improved performance.

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8-Bit Pla Adder

A logic array adder for executing the function S, COUT = A plus B plus CIN where S, A, B are eight-bit binary operands (Si), (Ai), (Bi) can be organized into one AND-array 1 and two OR-arrays 2, 3 each of fourteen rows, instead of the natural twenty five rows, by partitioning thirteen of the fourteen rows of the AND-array and grouping the product terms in a particular way. In addition, the inputs are entered into the AND-array as bit pairs Ai Bi via decoders 4, each having four output lines, only one of which lines is energized at a TIME, and the outputs are generated from the OR-arrays by Exclusive OR circuits 5 responsive to pairs of OR-array columns. The resultant logic array is of reduced area and improved performance. The details of the logic array organization are shown in the attached figure in which the following conventions have been used: Gi represents AND-array node connection if Ai Bi Gi represents AND-array node connection unless Ai Bi

Pi represents AND-array node connection if Ai : Bi

Pi represents AND-array node connection if Ai Bi

Hi represents AND-array node connection if Ai Bi : Ai Bi

Hi represents AND-array node connection if Ai Bi : Ai Bi

X represents left hand line coupling in a column line pair

of an OR-array

Y represents right hand line coupling in a column

line pair of an OR-array

* represents that Pi may replace Hi

** represents that Gi may replace Hi Partitioning of the AND-array is represented by bold interlining.

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