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Random Access Memory Cross Point Switch

IP.com Disclosure Number: IPCOM000086813D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Baker, JK: AUTHOR [+2]

Abstract

A cross-point switch function is achieved by the use of a random-access memory. Each of n input lines is effectively connected to one of n output lines. The lines are not actually connected but the 0 or 1 values on the input lines are reproduced on the selected output lines. For the value n = 4, four input lines I3, I2, I1 and I0 are to be connected to four output lines O3, O2, O1 and O0. As shown in TABLE A, 2n n-bit binary numbers are listed. The most significant bit corresponds to line 13 and also is designated Column 3 (C3). The least significant bit corresponds to line I0 and is also designated C0.

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Random Access Memory Cross Point Switch

A cross-point switch function is achieved by the use of a random-access memory. Each of n input lines is effectively connected to one of n output lines. The lines are not actually connected but the 0 or 1 values on the input lines are reproduced on the selected output lines. For the value n = 4, four input lines I3, I2, I1 and I0 are to be connected to four output lines O3, O2, O1 and O0. As shown in TABLE A, 2n n-bit binary numbers are listed. The most significant bit corresponds to line 13 and also is designated Column 3 (C3). The least significant bit corresponds to line I0 and is also designated C0.

Assume that input and output lines are to be connected as shown in the lefthand figure: I0 to O2, I1 to O3, I2 to O0, and 13 to 01. Therefore, in TABLE B, Column C0 of TABLE A, corresponding to line I0 is transposed to the 02 column of TABLE B; Column C1 of TABLE A is transposed to the O3 column of TABLE B; Column C2 of TABLE A is transposed to the O0 column of TABLE B; and Column C3 of TABLE A is transposed to the O1 column of TABLE B.

TABLE B is stored in a random-access memory and acts as a cross-point switch. When the memory is addressed by a binary address representing the combination of 0 and 1 bits on the input lines, the memory reads out corresponding 0 and 1 bits on the selected output lines. For example, if the bits appearing on lines I3, I2, I1 and I0 are 1001 (see arrow TABLE A), the corresponding bits 0110 in TA...