Hewlett-packard Company

Russ Campbell

Gary D Zimmerman

Terry M Nelson

Thomas G Berge

Michael E Sloane

Thomas T Pearse

Daniel L George

A peripheral unit is able to receive a plurality of control languages, check for an occurrence of a control language job boundary, and to function in response to each control language. For PCL the steps that determine when to check for occurrence of a control language job boundary are: identify the next command from the input data stream; determine if the identified command is not a PCL control character or calls for a mark to be made on the page, and if the page has not been previously marked. If the above criteria is met, the command and following data are examined to determine if a job boundary has occurred. Thus at the commencement of every formatted PCL page of data, a decision is made whether a job boundary has occurred. For PostScript the steps are: prescan the data stream. If a next command is an end-of-job marker then exit PostScript and return to identify the language of the input data. If the next command is an escape character and the current I/O protocol is not binary, the command and following data are examined to determine if a job boundary has occurred. A job boundary is determined by examining the input data sample and determining if its syntax is characteristic of a current job's control language or a different control language. If the syntax of the input data sample is different than the syntax of the current control language than a job boundary has occurred.

Automatic language boundary identification for a peripheral unit that

A page printer includes random access memory (RAM) whose capacity is insufficient to store certain page configurations; a processor; and a control memory that holds at least one data compression procedure. The page printer performs a font compression method that comprises the steps of: issuing a memory low/out signal when insufficient RAM is available to store portions of an input data stream; if raster graphics images are present in portions of the input data stream, attempting to compress those images to remove the memory low/out signal; if no raster graphics images are present in the input data stream, compressing font characters by use of a data compression procedure; and if the attempted compression of the raster graphics images is unsuccessful in removing the memory low/out signal, compressing font characters by use of a data compression procedure. The page printer also may be controlled to automatically data compress a large size font whose size exceeds a second threshold (which may be related to available printer RAM), under circumstances where a memory low/out signal is not present.

Page printer having automatic font compression

A peripheral unit converts an input data flow to page-arranged outputs and includes a random access memory capacity that is insufficient in size to accommodate an entire page of raster data. The peripheral unit also includes a processor and a control memory that holds a plurality of data compression procedures, each procedure exhibiting a different performance characteristic. The peripheral unit performs a method for compressing portions of the input data flow that includes the steps of: allocating the random access memory to portions of the input data flow; determining when an insufficient amount of random access memory is available for such allocation; employing a first data compression procedure on the input data flow portions to produce a compressed data portion; testing the compressed data portion to determine if a level of compression has been achieved that exceeds a threshold and, if not, employing succeeding data compression procedures and repeating the test for each procedure against a threshold, whereby the compression procedure that first enables a threshold level of compression to be achieved is the compression procedure employed to compress the data flow portion. Improved compression methods and techniques for handling input data flows with both integral and independent image descriptors are also described.

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Boise, ID, United States of America

Russ Campbell