Abstract: A working data store simultaneously serves as a FIFO buffer and operating memory. A portion of the FIFO buffer is reallocated for use as an operating memory as processing needs arise.

Abstract: Image or character data in the form of a rectangular array of binary 1s and 0s (bits) are divided into a plurality of segments, such as thirty-two by thirty-two bit segments or one bit by eight bit or byte segments. The image data is scanned for identifying all-zero segments (background) which are ignored and non-zero segments (foreground) which are transmitted or stored with offset and length (number of successive non-zero segments). The compacted image data is suitably indexed for facilitating image expansion using simple techniques. All compaction and decompaction machine operations are independent of bit-significant informational content of the segments. Presentation of the uncompacted data uses any printer or display type of device.

Abstract: A page modification method in a printer subsystem of the partial page buffer composing type. A printer subsystem receives a packet containing a page of characters, coded overlays/elisions, and combining data from an external source. The packet is translated into a linked list of character placement representations for each of the doubly indexed coded characters within the page. Elisions from the page are made by inhibiting the formation of a linked list segment for each character sequence within elision markers set out in the page. In contrast, coded character overlays are appended to the list as addenda. The list governs the placement of characters into a partial page buffer, whose contents are system accessible in row major order.

Abstract: A printer responds to channel commands including coded data received over a channel from a data processing unit by printing characters represented by the coded data using an electrophotographic printing arrangement. The coded data received by the printer is first translated into corresponding graphic codes or addresses by a translate table employing a predetermined translation code, following which the addresses are used to locate sets of character image bits stored within a plurality of character generator modules. Each set of character image bits is used to modulate a laser scan of a printing drum to effect printing of desired characters. Both the translate table and the character generator modules are program alterable, and the data stored therein can be loaded directly from or changed in response to data and instructions from the data processing unit.

Abstract: In a buffered printer in which lines of character code bytes representing characters to be printed are translated into lines of graphic code bytes by a translate table, assembled into a page format in a page buffer and applied to a character generator module to select sets of character image bits in storage locations within the module corresponding to the graphic code bytes, the selected sets of character image bits being applied to modulate a scanning laser beam to effect printing of the desired characters, each line of graphic code bytes provided by the translate table is entered into the page buffer in a selected location determined by a channel command associated with the previously entered line. Each "write and no space" command accompanying a line of graphic code bytes stored in the page buffer results in the immediately following line of graphic code bytes being stored in the same location. The two different lines are combined in accordance with a merge algorithm.