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Serial Multiplying

IP.com Disclosure Number: IPCOM000098899D
Original Publication Date: 1958-Oct-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 3 page(s) / 61K

Publishing Venue

IBM

Related People

Moore, RL: AUTHOR [+3]

Abstract

The circuit effects a multiplication of a Factor B (multiplicand) by a Factor A (multiplier) in the following manner. There is provided a magnetic drum storage device having a Factor A storage track 1, a storage track 3, and a temporary storage track 2, each track having appropriate read and write heads as required. Each of the tracks 2 and 3 contains ten serially arranged groups of storage, each having eight serially arranged positions of order (read low order first), each order position further containing four serially arranged bit positions in which a decimal digit may be stored in combinational 1, 2, 4, 8 bit form. Data are represented in track 1 in a different form than in tracks 2 and 3.

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Serial Multiplying

The circuit effects a multiplication of a Factor B (multiplicand) by a Factor A (multiplier) in the following manner. There is provided a magnetic drum storage device having a Factor A storage track 1, a storage track 3, and a temporary storage track 2, each track having appropriate read and write heads as required. Each of the tracks 2 and 3 contains ten serially arranged groups of storage, each having eight serially arranged positions of order (read low order first), each order position further containing four serially arranged bit positions in which a decimal digit may be stored in combinational 1, 2, 4, 8 bit form. Data are represented in track 1 in a different form than in tracks 2 and 3.

The Factor A storage track 1 is also divided into ten groups, each of eight positions of order. These are arranged order for order with the storage track 3. Only the first nine groups of the track are used. Entry of Factor A into storage track 1 is effected one digit at a time under the control of a relay setup or entry device 4.

Factor A is stored in the form of a set of adder entry signals, rather than in coded 1, 2, 4, 8 bit form as in the previously mentioned storage tracks. Each adder entry later causes a digit of Factor B to be entered into an adder 5. The number of signals representing each digit of Factor A is equal to the digit numeric value. Their location is indicative of the order of the digit being represented.

Thus, in a representative multiply operation of a Factor A of 592, for example, times a Factor B, the Factor A digit of 5 in the hundreds order is stored as five individual signals, one in the hundreds location of each of the last five groups of track 1. The Factor A digit of 9 is stored as nine individual signals, one in the tens location of each of the last nine groups, while the Factor A digit of 2 is stored as two individual signals, one in the units location of each of the last two groups.

Since only one bit per order is needed for multiplier signal storage, it is possible to store more than one multiplier on storage track 1, and these could be selected as desired.

After Factor A is stored in track 1, the successive orders of Factor B are each set up, in turn, under the control of a relay setup or entry device 6. A single cycle of multiplication (Factor A times one digit of Factor B) involves two magnetic drum revolutions or cycles.

During the first nine groups in the first drum cycle, o...