Editing Burroughs Large Systems (section)

==Primary lines of hardware==
Hardware and software design, development, and manufacturing were split between two primary locations, in [[Orange County, California]], and the outskirts of [[Philadelphia]]. The initial Large Systems Plant, which developed the B5000 and B5500, was located in [[Pasadena, California]] but moved to [[City of Industry, California]], where it developed the B6500.  The Orange County location, which was based in a plant in [[Mission Viejo, California]] but at times included facilities in nearby [[Irvine, California|Irvine]] and [[Lake Forest, California|Lake Forest]], was responsible for the smaller B6x00 line, while the East Coast operations, based in [[Tredyffrin, Pennsylvania]], handled the larger B7x00 line.  All machines from both lines were fully object-compatible, meaning a program compiled on one could be executed on another.  Newer and larger models had instructions which were not supported on older and slower models, but the hardware, when encountering an unrecognized instruction, invoked an operating system function which interpreted it.  Other differences include how process switching and I/O were handled, and maintenance and cold-starting functionality.  Larger systems included hardware process scheduling and more capable input/output modules, and more highly functional maintenance processors.  When the Bxx00 models were replaced by the A Series models, the differences were retained but no longer readily identifiable by model number.