Laser printer controller data alignment device

Abstract

The laser printer controller for accepting a page of data to be printed in ASCII character format converts the data into a dot-by-dot character pattern for packing in a vertically scrolling partial page bit map. The alignment device within the laser printer controller provides the means for effectively aligning the randomly positioned dot-by-dot character patterns having a first word orientation with respect to its storage boundaries with a second word orientation necessitated by the fixed word storage boundaries of the partial page bit map. The alignment device includes means for partitioning two adjacent words in their first word orientation of the character pattern for alignment with the second word orientation of the page bit map, packing the two respective portions of the adjacent words into a one word format, rotating or manipulating the two word portions within the one word format for proper bit sequence for a single print data word of the second word orientation. The alignment device also includes means for saving the generated print data word in the page bit map by inclusively ORing the data word to be stored into the page bit map with the data that is currently in the page bit map whereby to prevent partial character loss for over-strike characters. The page bit map of the laser printer controller includes scrolling means which provides for the output of one dot line of data to be printed to be interleaved with the loading of the data into the page bit map. As the top, or current dot line is moved from the page bit map for transfer to the print engine, that line of the page bit map is cleared and moved, by appropriate pointers to the bottom of the partial page bit map and there made available to receive newly generated print data words.