Xerox Corporation

Glen D Jones

Vinod K Kadakia

Ronald E Rider

Kedar D Parikh

Michael J Raffetto

A predictor bit pattern comprising selected bits of the current and previous raster scan lines and a method of predicting a plurality of bits per clock are disposed. Generally, a predictor is used prior to the encoding of data to increase the compression. The current bit in a bit stream is compared to the predicted value and a one is output when the two values are not equal. An efficient predictor will reduce the number of ones in a bit stream, which increases the zero run lengths and increases the efficiency of a run length encoding system. The described bit pattern contains bits close to the current bit to efficiently predict text data, bits distant from the current bit to efficiently predict halftone data, and ignores a plurality of intermediate bits to reduce hardware costs. A two step process is also described to allow a plurality of bits to be predicted in parallel. A circuit for performing this process comprises a buffer for storing the previous and current line data, two registers for holding the previous and current line prediction data patterns and two PROMs for performing the two step prediction.

Hardware implementation of 2 line/11 element predictor

A circuit to encode image data. The circuit receives image data in four bit nibbles which are either all-zero nibbles or terminating nibbles containing at least one non-zero bit. The circuit output is a series of code words, each a multiple of four bits and up to twenty-four bits long, packed into eight bit output words. Each code word contains a first part containing a run length specifying the number of received all-zero nibbles and a second part specifying the bit pattern of the terminating nibble. The circuit uses PROMs for the look-up and control elements and a pipeline of registers to allow high speed operation.

Hardware implementation of 4-pixel code encoder

Improved apparatus for wiring through a wall of a sealed enclosure is disclosed. A printed circuit board is mounted on and extends through a slot in the wall, said board etched so that a plurality of conducting lines are provided from inside to outside the enclosure. Standard printed circuit board connectors are mounted on and soldered to the board providing convenient means for the attachment of cables to the board. Finally, the slot space between the printed circuit board and the wall is sealed with a rubber grommet to complete the sealing of the enclosure.

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Orange, CA, United States of America

Glen D Jones