GSI Technology, Inc.
NON-DESTRUCTIVE MEMORY ARRAY TO IMPLEMENT A FULL ADDER

Abstract:

A non-destructive memory array implements a full adder. The array includes a column connected by a bit line and a full adder unit. The column stores a first bit in a first row of the bit line, a second bit in a second row of the bit line, and an inverse of a carry-in bit in a third row of the bit line. The full adder unit stores, in the second and third rows of the bit line, a sum bit and a carry out bit output, respectively, of adding the first bit, the second bit and the carry-in bit. The full adder unit does not overwrite any of the bits when a full adder table indicates that the sum bit and the carry out bit are equivalent to the second bit and the carry-in bit.