Browse Prior Art Database

Checking System For Table Look Up Calculator

IP.com Disclosure Number: IPCOM000095433D
Original Publication Date: 1964-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Pugmire, JM: AUTHOR [+2]

Abstract

A table look-up calculator includes storage device 1. This has a number of locations each storing a TLU word to which access is obtained by specifying X and Y addresses. These are developed from operands held in shift registers A and B via decoder 3.

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Checking System For Table Look Up Calculator

A table look-up calculator includes storage device 1. This has a number of locations each storing a TLU word to which access is obtained by specifying X and Y addresses. These are developed from operands held in shift registers A and B via decoder 3.

In operation, one digit of each operand is shifted out under the control of control unit 5 to operand register 2 and applied to decoder 3 which converts the operands into X and Y addresses. The result word so selected is returned to register B. Any carry developed is applied to register 2 in order to be taken into account, when the next pair of operand digits is added. Each operand has associated with it parity bit P which is not shifted. In order that the parity of the result can be developed, the result words stored in device 1 include digits. These represent the parity change which occurs when the two operand digits associated with that word are subjected to the arithmetic operation concerned.

The operation is performed in excess-3 code for both additions and increments. This is summarized by the table which represents a section of the table contained in device 1.

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