Abstract: A method and system for accessing data by an application program is disclosed. The application program issues a data request to a data storage system. In response, the data storage system loads into memory a data node corresponding to the data request. The data node is stored as part of a data structure. The data storage system returns a reference to the application program, which is then used to access the node. The application program may further instruct the data storage system to de-allocate a node when available memory is low or when it is no longer using the node.

Abstract: A method and system for accessing data by an application program is disclosed. The application program issues a data request to a data storage system. In response, the data storage system loads into memory a data node corresponding to the data request. The data node is stored as part of a data structure. The data storage system returns a reference to the application program, which is then used to access the node. The application program may further instruct the data storage system to de-allocate a node when available memory is low or when it is no longer using the node.

Abstract: Embodiments of the present invention are directed to a microcontroller system incorporating a DMA system and to a method of accessing a memory by a plurality of processing units. In embodiments of the present invention, the microcontroller system includes a plurality of processing units, a DMA module, and an interface to an external memory system. The DMA module controls access to the external memory system by the processing units on a time shared basis by allocating time slots to each of the plurality of processing units. The processing units can access the external memory system during their assigned time slots. Data transfers to and from the memory are accomplished in packets having a fixed maximum size.

Abstract: A printing system and method performs lossy compression on a bitonal image when the printing system runs out of available memory for processing a page. The lossy compression is performed by dividing the image into subregions and by then determining a contone value for each subregion. Next, each contone value is converted to a bitonal value (i.e. either a "1" or a "0") to achieve lossy compression. In converting the contone values to bitonal values, the system determines the error associated with each conversion and diffuses the error to adjacent subregions using a random perturbation technique to determine the proportion of the error to diffuse to each subregion. When compressing color images, contone values are determined for each color plane. A relative color ordering of each contone value is also stored and used in converting the contone values to bitonal values in order to solve phasing and color alignment problems which would otherwise arise.

Abstract: A system and process for digital printing divides an image area into segments, defines display lists for each segment, generates graphic primitives from page description language commands, stores the graphic primitives in the display lists, and adaptively compresses and converts the contents of display lists as memory requirements exceed available memory capacity. Display lists contain either uncompressed pixel representations, compressed pixel representations, graphic primitives, or combinations of the foregoing.

Abstract: A daisy wheel printing unit includes a wheel data memory housing wheel data such as kinds of characters provided in the daisy wheel by which it can be discriminated. The printing unit compares printing commands supplied to the printer and discriminates whether or not the characters to be printed included in the daisy wheel now being set in the printer. If it is discriminated that the characters to be printed are not included in the daisy wheel now being set in the printer, the user of the daisy wheel printing unit can select a desired printing mode from a plurality of printing modes including treatment for the above characters before the start of the printing operation of the document.

Abstract: A control apparatus for transferring characters from a font memory to a printer including a microprocessor which controls input and output of characters to and from a strip memory, tracks the status of input/output operations to insure overwriting of the memory does not occur, and supplies a minimal amount of control information to hardwired circuitry from which character building processes are autonomously controlled.