Patent ID: 6961741
Filing Date: 2005-11-01
Classification: G06F,H03K

Abstract:
1. A programmable look-up table apparatus comprising: a plurality of programmable data storage cells each providing a cell output signal indicative of data stored therein; means for selecting one of said cell output signals as an output signal and comprising the look-up table apparatus being divided into equal first and second halves, excluding said last selection means, where each half comprises half of the remaining selection means, half of said programmable data storage cells, and half of the input signals; first means for selecting a selection input for a final selection means in each of said first and second halves to be a first input signal from the second half during a normal mode and a carry out signal from a previous bit operation during a two-bit arithmetic mode, said last selection means receiving a second input signal from the second half; and second means for connecting an output from said final selection means of said first half as a least significant output bit of the two-bit arithmetic operation and for connecting an output of said final stage of said second half as a most significant output bit of the two-bit arithmetic operation during the arithmetic mode, said second means also allowing normal selection operation using one of the input signals during the normal mode.