International Business Machines Corporation

Howard C Jackson

Stephen Dale Hanna

Nelson K Arter

Charles D Johnson

George W Brock

Steven G Ludwig

Charles H Morris, Iii

Lawrence M Ammann

Edward P Lutter

Daniel J Collins, Jr

James Warren Leggate

A method and apparatus for data transmission transmits both compressed and noncompressed data over each of a plurality of transmission paths. A data identification pattern is used to request a type of data from a memory having a plurality of data types stored within it. A handshaking control module is provided to select the correct type of data from the memory and place it on the output of the memory. The requested data type is then transmitted to a data decompression module via an interface. The data transmission can occur on any one of a plurality of data transmission paths when the data being transmitted is either Linework or Linework control data. When the data decompression module receives the data, it is then routed to any one of a plurality of data decompression systems based upon the results of the evaluation of the data identification pattern. The routing of the received data is wholly dependent upon the data identification pattern and independent of which transmission path the data was received on.

Compressed data transmission over a plurality of transmission paths

A memory system is enabled to access data for multiple objects in an interleaved fashion. Object data is retrieved from a system bus via an input interface, is temporarily stored in a limited data memory of the memory system and object headers are stored in a header memory. Each object to be printed has an object header and may, or may not, have associated object data. A 'skip' function is provided to terminate a transfer function if object data is not ready. The memory system is enabled to retrieve all data in an object or cancel the object before the endo f data is reached. An identifier is associated with each data object and is subsequently reused after the original data object is transferred or cancelled. A plurality of request levels are assigned each data request to indicate the urgency of a data request, enabling multiple memory systems to operate from a single data transfer function.

Input interface for a raster object memory in a method, system and program

An output interface allows a user circuit to access data for multiple objects in an interleaved fashion. Status information is provided to guarantee data availability before each transfer sequence is started. An identifier is provided for each object. Each identifier, after data transfer has ended, may be subsequently reused to identify a different object. The interface provides the ability to retrieve all data in an object or to cancel the object before reaching the end and discarding the unretrieved data. The objects are provided to the appropriate processing mechanisms within the printer to implement a printing task. These objects correspond to images and text to be printed on a page. Object data is temporarily stored in limited data memory of the memory system and object headers are stored in header memory before transfer via the output interface. Each object to be printed has an object header and may, or may not, have associated object data.

Output interface for a raster object memory in a method, system and program

Software driven controller emulator includes hardware apparatus for emulating the controller at a speed faster than the software driven emulator, incorporating predicting a next event to be emulated and preactivating dedicated logic to emulate the controller driving the next event. In case of errors, the hardware controller sets a code signal and returns emulation to the software driven emulator for error recovery identified by the code signal.

Fast emulator using slow processor

In a rotating head magnetic tape transport, the tape is maintained stationary as the head sweeps a selected data track. A length of tape is buffered in a vacuum column between a supply spool and a rotating head station. A take-up spool on the opposite side of the head station is controlled by minimizing the overshoot or undershoot of the motor driving the take-up spool as the radius of the amount of tape on the spool increases or decreases (i.e., change). After a step operation, the overshoot or undershoot of the motor is measured and compared with a reference range to determine if the undershoot or overshoot is within the reference range. If the measured quantity is within the reference range, no adjustment is made. If the measured quantity is outside of the voltage level or reference range, the gain of the take-up motor is adjusted.

Adaptive voltage control of motor in an incrementing magnetic tape

A track or stripe tape positioner for a helical scan or rotary head recorder uses digital techniques. The expected step size is preset into a counter. During the next phase, a calibration phase, the tape is stepped through a plurality of stripes whereat the preset value is adjusted to measured values. In the third phase, the average step size is maintained subject to certain averaged changes thus providing a high degree of noise rejection to ensure reliable incremental stepping of a record tape through the recorder.

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Loveland, CO, United States of America

Howard C Jackson