05894565 is referenced by 145 patents and cites 45 patents.

A field programmable gate array has a matrix of programmable logic cells and a bus network of local and express bus lines. The bus network effectively partitions the matrix into blocks of cells with each block having its own distinct set of local bus lines. Express bus lines extend across more than one block of cells by means of repeater switch units that also connect local bus lines to express bus lines. The grouping of cells into blocks with repeaters aligned in rows and columns at the borders between blocks creates spaces at the corners of blocks that can be filled with RAM blocks, other memory structures, specialized logic structures or other dedicated function elements that are connected to the bus network. The RAM blocks can be single or dual port SRAM addressed through the bus lines. Pairs of adjacent columns of RAM blocks may be commonly addressed by the same set of bus lines. Other specialized or dedicated logic might also fill those corner spaces. Logic cells are directly connected to neighboring cells, including diagonally adjacent cells, and are also connected to local bus lines. The arrangement of express bus lines is preferably staggered in such a way that they connect to non-consecutive repeaters in an alternating manner. I/O pads connect to cells at the perimeter of the matrix and to the bus network. Preferably, pads are connectable to more than one cell and more than one row or column of bus lines, and each perimeter cell can be connected to any of several I/O pads.

Title
Field programmable gate array with distributed RAM and increased cell utilization
Application Number
8/650477
Publication Number
5894565
Application Date
May 20, 1996
Publication Date
April 13, 1999
Inventor
Robert B Luking
Catonsville
MD, US
Martin T Mason
San Jose
CA, US
Frederick C Furtek
Menlo Park
CA, US
Agent
Mark Protsik
Thomas Schneck
Assignee
Atmel Corporation
CA, US
IPC
G05B 19/05
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