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# Drum Calculator

IP.com Disclosure Number: IPCOM000097226D
Original Publication Date: 1962-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

IBM

## Related People

Roth, RI: AUTHOR [+2]

## Abstract

The calculator uses serial batch techniques in combination with a rotating drum. The system performs addition and, by multiple additions, it also performs multiplication and division.

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Drum Calculator

The calculator uses serial batch techniques in combination with a rotating drum. The system performs addition and, by multiple additions, it also performs multiplication and division.

Each number which is to be added is stored in horizontal rows on drum 11 by drum input circuitry 10. The units digits of all numbers are aligned in one track on the drum. The tens digits of all numbers are aligned in the next track, etc. During the first step in the addition process, reading circuitry 12A serially reads the units digits of the various numbers stored on the drum. These digits are gated through switching network 14 to shifting accumulator 16. Accumulator 16 sums the digits which it receives from switch 14.

After all units digits are summed, all digits in 16 are shifted right one position. The units digit of the sum is shifted out of 16 to generate the first digit of the result. At the same time, the carries are all shifted right one position. Next, reading circuitry 12B serially reads the tens digits of each number. These digits are gated through switch 14 to accumulator 16. The latter now adds each tens digit to the first order carry from the units digit. The carry digit is in the low order position of 16, since all the digits are shifted to the right. The shifting and summing process repeats until all of the tracks on the drum are summed.

In an alternative arrangement, input circuitry 10 and reading circuitry 12A, 12B, etc., are simplified by mountin...